ArticlePDF AvailableLiterature Review

Abstract and Figures

Human alveolar echinococcosis (AE) is known to be common in certain rural communities in China whilst it is generally rare and sporadic elsewhere. The objective of this study was to provide a first estimate of the global incidence of this disease by country. The second objective was to estimate the global disease burden using age and gender stratified incidences and estimated life expectancy with the disease from previous results of survival analysis. Disability weights were suggested from previous burden studies on echinococcosis. We undertook a detailed review of published literature and data from other sources. We were unable to make a standardised systematic review as the quality of the data was highly variable from different countries and hence if we had used uniform inclusion criteria many endemic areas lacking data would not have been included. Therefore we used evidence based stochastic techniques to model uncertainty and other modelling and estimating techniques, particularly in regions where data quality was poor. We were able to make an estimate of the annual global incidence of disease and annual disease burden using standard techniques for calculation of DALYs. Our studies suggest that there are approximately 18,235 (CIs 11,900-28,200) new cases of AE per annum globally with 16,629 (91%) occurring in China and 1,606 outside China. Most of these cases are in regions where there is little treatment available and therefore will be fatal cases. Based on using disability weights for hepatic carcinoma and estimated age and gender specific incidence we were able to calculate that AE results in a median of 666,434 DALYs per annum (CIs 331,000-1.3 million). The global burden of AE is comparable to several diseases in the neglected tropical disease cluster and is likely to be one of the most important diseases in certain communities in rural China on the Tibetan plateau.
Content may be subject to copyright.
The Global Burden of Alveolar Echinococcosis
Paul R. Torgerson
1,2
*, Krista Keller
1
, Mellissa Magnotta
1
, Natalie Ragland
1
1Ross University School of Veterinary Medicine, St. Kitts, West Indies, 2Section of Epidemiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
Abstract
Background:
Human alveolar echinococcosis (AE) is known to be common in certain rural communities in China whilst it is
generally rare and sporadic elsewhere. The objective of this study was to provide a first estimate of the global incidence of
this disease by country. The second objective was to estimate the global disease burden using age and gender stratified
incidences and estimated life expectancy with the disease from previous results of survival analysis. Disability weights were
suggested from previous burden studies on echinococcosis.
Methodology/Principal Findings:
We undertook a detailed review of published literature and data from other sources. We
were unable to make a standardised systematic review as the quality of the data was highly variable from different countries
and hence if we had used uniform inclusion criteria many endemic areas lacking data would not have been included.
Therefore we used evidence based stochastic techniques to model uncertainty and other modelling and estimating
techniques, particularly in regions where data quality was poor. We were able to make an estimate of the annual global
incidence of disease and annual disease burden using standard techniques for calculation of DALYs. Our studies suggest
that there are approximately 18,235 (CIs 11,900–28,200) new cases of AE per annum globally with 16,629 (91%) occurring in
China and 1,606 outside China. Most of these cases are in regions where there is little treatment available and therefore will
be fatal cases. Based on using disability weights for hepatic carcinoma and estimated age and gender specific incidence we
were able to calculate that AE results in a median of 666,434 DALYs per annum (CIs 331,000-1.3 million).
Conclusions/Significance:
The global burden of AE is comparable to several diseases in the neglected tropical disease
cluster and is likely to be one of the most important diseases in certain communities in rural China on the Tibetan plateau.
Citation: Torgerson PR, Keller K, Magnotta M, Ragland N (2010) The Global Burden of Alveolar Echinococcosis. PLoS Negl Trop Dis 4(6): e722. doi:10.1371/
journal.pntd.0000722
Editor: Simon Brooker, London School of Hygiene & Tropical Medicine, United Kingdom
Received January 8, 2010; Accepted April 29, 2010; Published June 22, 2010
Copyright: ß2010 Torgerson et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: This work was supported by a grant from the World Health Organization. This was part of a commissioned work as part of a global burden of food-
borne diseases study. The sponsors only had a limited role in the study design. The sponsors also provided access to databases for researching the material. The
data analysis, decision to publish, and preparation of the manuscript were undertaken solely by the authors, although the sponsors indicated that they would like
to see this information contained in the manuscript published in the scientific literature.
Competing Interests: The authors have declared that no competing interests exist.
* E-mail: ptorgerson@vetclinics.uzh.ch
Introduction
Human alveolar echinococcosis (AE) is caused by the larval
stage of the fox tapeworm Echinococcus multilocularis. It is amongst
the world’s most dangerous zoonoses. Transmission of AE to
humans is by consumption of parasite eggs which are excreted in
the faeces of the definitive hosts: foxes and, increasingly, dogs.
Naturally the parasite transmits between foxes or dogs and small
mammals whilst humans are aberrant intermediate hosts
(Figure 1). Human infection can be through direct contact with
the definitive host or indirectly through contamination of food or
possibly water with parasite eggs. Geographically E. multilocularis is
confined to the northern hemisphere, but within that range has a
wide distribution (Figure 2) [1]. In humans, infection results in a
metacestode in the liver. This is a slowly growing infiltrative space
occupying lesion. If untreated, this lesion will result in clinical signs
such as abdominal mass and/or pain, jaundice, and ultimately
liver failure [2]. In the late stages of the disease, the parasitic lesion
can metastasize resulting in a variety of symptoms. Treatment
options include liver resection to remove the parasite mass and
chemotherapy using benzimadazoles is now being increasingly
used. Survival analysis indicates that with judicious surgical and
chemotherapeutic treatment the prognosis is relatively good [3].
However, chemotherapy is required continuously for many years,
sometimes for the remainder of the patient’s life to achieve success.
In the absence of this expensive treatment the disease normally has
a fatal course.
Human AE is an emerging disease in Europe. Studies in wildlife
are detecting the parasite in new areas [4]. It is not yet clear if the
parasite range is spreading or increasing surveillance has lead to
greater detection rates. What is certain is that increasing fox
populations in Europe are correlated with the greater numbers of
cases of AE reported in Switzerland [5]. In Asia a major endemic
focus was detected in China [6] with large numbers of human
cases – in some communities 5% or more of the population is
infected [7]. In such areas there is, not only high infection rates in
humans, but a high prevalence of infection with the adult parasite
in the dog population [8]. In central Asia there are also reports of a
spill over of E. multilocularis into the dog population [9] and this
may indicate an increasing threat of transmission to humans.
Elsewhere there are increasing reports of AE being detected by
surgeons in countries such as Russia and Turkey.
Control of the parasite is possible, for example, through the
judicious use of praziquantel baits distributed to foxes [10]. Some
www.plosntds.org 1 June 2010 | Volume 4 | Issue 6 | e722
studies have indicated that risk factors such as contamination of
food or water are a likely conduit of human infection [11,12] and
could suggest alternative strategies to prevent human infection.
However, whatever the intervention strategy, the economic
efficiency of control will depend upon the societal burden of
disease. The purpose of this study was to estimate the annual
global burden of AE.
Materials and Methods
Initially all countries, endemic for E. multilocularis, were
identified. These were countries that were known to have
autochthonous human cases of AE and/or E. multilocularis
identified in animal populations. In addition, neighbouring
countries where there were no known reports were also identified
as likely endemic areas. The list of countries believed to be
endemic for E. multilocularis is given in Table 1.
Sources of information
Literature searches were undertaken in any relevant databases
that could be accessed. These included all the following scientific
databases: Pubmed, Medline, Science Citation Index, Scopus,
East View (Chinese and Russian databases), Russian Scientific
electronic library, and Google Scholar. This was supplemented by
direct contacts with known persons working in the field in various
countries. In addition, further information was solicited by directly
contacting individuals who had authored manuscripts by the email
address in the correspondence section. Key words used were
Echinococcus multilocularis and alveolar echinococcosis for initial
screening. Where appropriate the search term was also translated
into the language of the relevant database. For each country a
systematic search was undertaken to locate data from that country
eg Echinococcus multilocularis AND France. All literature was initially
screened. Most literature was not useful for calculating incidence
rates (for example individual surgical case reports); although in a
number of cases such individual reports confirmed that the disease
was endemic in the country or region of interest. Inclusion criteria
depended on the amount of available information from that
country. Because of wide variability in the quality of the data from
different countries it was not possible to use a standard procedure
across all endemic countries. When there were extensive
prevalence and/or incidence reports, particularly indicating whole
country incidences, these were used as the primary data sources.
However, for many if not most countries, such data was not
available. In these cases the reports of individual cases or case
studies were utilized to, at the very least, prove the presence of the
disease (and in a few cases there were only reports from animal
infections). The body of literature on experimental research (eg
experimental infections of definitive or intermediate hosts) was, in
the whole, of little relevance to this study.
Calculations of incidence
For a number of countries such as Switzerland [5] or Germany
[13], accurate figures for the annual numbers of cases were easily
identified. This is because they had up to date national databases
and/or accurate methodology for capturing the estimated
numbers of cases each year. In other countries, such as
Kyrgyzstan, accurate reporting figures were available based on
histological confirmed cases presented for treatment from hospitals
(unpublished). However, it is believed that, in low-income
countries such as Kyrgyzstan, the reported cases are likely to
substantially underestimate the total numbers of cases as a
substantive number of cases are likely to remain undiagnosed
because of the relative expense of seeking medical treatment.
China is believed to account for the majority of global AE cases.
Estimates were based on mass screenings by ultrasound giving a
prevalence estimate. Many such reports also indicated groups
(such as Tibetan pastoralists) who were at particular risk of
infection. In this region there were a number of large prevalence
studies and epidemiological studies based on ultrasound confir-
mation of diagnosis. These often consisted of several thousand
individuals and hence gave samples of populations at risk. In
addition particular groups at risk such as Tibetan pastoralists were
identified. The studies used are given in Table 2. In total in studies
spanning the first decade of the 21
st
century over 36,000
individuals have been screen by ultrasound over large areas of
Ningxia autonomous region, Sichuan, Gansu, and Qinghai
provinces. The total number of individuals currently affected with
AE was estimated from these prevalence studies and the total
populations at risk. This data was then converted into an annual
incidence of AE for these populations. Survival analysis of a series
of cases from Switzerland suggested that the 50% survival rate of
approximately 8 years if treatment is not available for individuals
with a mean age of presentation in their early 50s [3]. This can rise
to approximately 11 years for younger subjects. If endemic
stability is assumed then there will be approximately 6.1% of
infected young adults dying from the disease rising to approxi-
mately 8.2% of infected adults who are aged in their early 50s.
Hence the annual incidence is approximate 6.1%–8.2% of the
detected ultrasound prevalence in the population of these
respected age groups.
China has large populations in rural areas that are potentially
exposed to this parasite. An estimate was performed of the
population at risk by examining population data county by county
from Chinese Census data. The estimates of the mean prevalence
in the population at risk were estimated from relative risk of
various ethnic communities from population studies and the
proportions these communities make up in the general population.
There are also reports of AE in inner Mongolia and Xinjiang but
these tend to have considerably few cases then the main endmic
area of the Tibetan plateau.This prevalence data was extrapolated
Author Summary
Human alveolar echinococcosis (AE), caused by the larval
stage of the fox tapeworm Echinococcus multilocularis,is
amongst the world’s most dangerous zoonoses. Transmis-
sion to humans is by consumption of parasite eggs which
are excreted in the faeces of the definitive hosts: foxes and,
increasingly, dogs. Transmission can be through contact
with the definitive host or indirectly through contamina-
tion of food or possibly water with parasite eggs. We made
an intensive search of English, Russian, Chinese and other
language databases. We targeted data which could give
country specific incidence or prevalence of disease and
searched for data from every country we believed to be
endemic for AE. We also used data from other sources
(often unpublished). From this information we were able
to make an estimate of the annual global incidence of
disease and disease burden using standard techniques for
calculation of DALYs. Our studies suggest that AE results in
a median of 18,235 cases globally with a burden of 666,433
DALYs per annum. This is the first estimate of the global
burden of AE both in terms of global incidence and DALYs
and demonstrates the burden of AE is comparable to
several diseases in the neglected tropical disease cluster.
Burden of Alveolar Echinococcosis
www.plosntds.org 2 June 2010 | Volume 4 | Issue 6 | e722
to the estimated population at risk and then converted to incidence
based on the results of survival analysis [3].
A flow chart illustrating the methodology used in the study is
given in figure 3.
Incidence estimates from case series
In Turkey and Russia total numbers of cases for echinococcosis
are recorded. In Russia in 2002 there were 3,274 cases of cystic
echinococcosis (CE) notified [14]. In Turkey 14,789 cases of CE
were notified in the 5 years 2001–2005 [15]. Separate information
for AE was not available. This may be because it has only recently
been made notifiable such as in Turkey [16] or because CE and
AE cases are not distinguished in official figures. Despite this, in
Turkey there are some nationwide figures which give a minimum
estimate. However, there are a number of case series of
echinococcosis published by surgical units which differentiate
between CE and AE. The relative proportion of AE to CE cases in
such surveys can be used to estimate the likely number of AE cases
for the whole country. These case series (Tables 3 and 4) are a
means to calculate the total incidence of AE from the relative
incidence and total country incidence of CE. In addition, in
Turkey there was one detailed case series of echinococcosis with
CNS involvement that identified 16 cases of AE with cerebral
involvement over a 5 year period from neurosurgical units in
Turkey [17]. A large study in China suggested that 4% of AE cases
had neurological involvement [18]. Likewise, a large European
study found 17 of 559 (3%) cases of AE had brain involvement
[19]. The likely number of AE cases can then be estimated by
assuming that the proportion of cerebral AE cases in Turkey was
similar to these reported case series.
Estimates of DALYs
To calculate DALYs standard techniques were used [20]. The
years of life lost (YLLs) were calculated on the assumption that the
disease is fatal within an average of 8 years of diagnosis if
untreated. If treatment is available then the prognosis was assumed
to be reasonable with just 2–3 YLLs. These assumptions are based
on previously published survival analysis [3]. In order to calculate
the years lived with disability (YLDs) is was necessary to assign a
disability weight. As no accepted disability weight has yet been
assigned to alveolar echinococcosis the disability weight for
carcinoma of the liver was used as previously [7]. The years lived
with the disability again depends on where the cases are presented
and available treatment options. Where there is no treatment,
Figure 1. The life cycle of
Echinococcus multilocularis
.Man is infected as an aberrant intermediate host.
doi:10.1371/journal.pntd.0000722.g001
Burden of Alveolar Echinococcosis
www.plosntds.org 3 June 2010 | Volume 4 | Issue 6 | e722
death can be assumed within a mean of 8 years for patients in their
50s, but this increases to 11 years for someone presenting in their
20s [3]. In low income countries a disability weight for pre
terminal liver cancer (0.200) was assigned for 6–9 years with a
disability weight for 2 years living at the disability weight for
metastatic and terminal stages (0.75–0.81) [21] .The number of
years at these weights depended on the age specific incidence (see
below). In those countries where advanced medical treatments
lead to a successful outcome, a disability weight of 0.200 for mild
disease for the average length of treatment (7 years) [3]. This was
based on the fact that liver cancer has similar symptomatology to
AE [7].
Age and gender specific incidence
This data are important in estimating the burden of disease. For
Europe a large data set of 559 [19] was used as the basis for the
age and gender distribution of cases and hence the age weighting
and YLLs for the estimated DALYs. For China prevalence data
only was available, but much was age and gender stratified and
was used to calculate the age and gender specific incidence after
adjusting for bias by comparing the sampled population with the
age and gender profile of the general population using census data
[7]. Other counties including Turkey had case series reports which
indicated age and gender of cases, although in some instances only
the mean age was given. Unpublished data for case series from
Kyrgyzstan were used and assumed to be representative of similar
ex-Soviet states where data was not available.
Stochastic analysis
Based on the quality of the data we were able to assume some
countries (eg Switzerland) had accurate estimates of incidence,
whilst others it was much more uncertain, particularly when
estimates had to be created from modelling or extrapolation from
neighbouring regions. A Monte-Carlo routine was written to
resample estimates of incidence from each country based on the
likely probability distribution of the total case incidence. This was
similar to methods described previously [7,22]. Distributions were
based on a number of factors from the available data including
possibilities of missing data.
Results
Incidence
For China in total we estimated there are 230,000 individuals
presently suffering from AE and a total population at risk of some
22.6 million in 7 provinces (Table 5). Assuming most of these go
untreated and hence have a fatal outcome, this was used to
estimate the incidence from age stratified life expectancy following
diagnosis. This gives an annual incidence of approximately 16,629
new cases per annum.
Russia is a huge endemic area stretching from Eastern Europe
to Siberia. We estimated that there are approximately 1,180 cases
per year in this country. AE is found throughout the northern
parts of Asia with important foci in central Asia and Turkey. The
estimates for the annual numbers of cases in Asia excluding Russia
are given in Table 6. The estimated numbers of cases from Europe
from countries that are endemic for AE are given in the Tables 7
and 8, with the references supporting the estimate. Although
North America is endemic for E. multilocularis in animal hosts there
is very little evidence for transmission to humans presently.
We estimate that the median estimate of the total numbers of
AE cases in the world is 18,235cases per year with 95% CIs of
11,932–28,156. Of these 91% of cases are believed to be in China
with just 1,606 occurring outside China.
Figure 2. Global distribution of AE.
doi:10.1371/journal.pntd.0000722.g002
Burden of Alveolar Echinococcosis
www.plosntds.org 4 June 2010 | Volume 4 | Issue 6 | e722
Estimated DALYs
Globally YLLs due to AE was estimated at 616,897 (CIs
296,485 – 1.2 million). Again China had most of YLLs and as a
proportion was even higher than the incidence as it was assumed
that the majority of cases in China did not receive treatment. The
age of onset was also younger then compared to Europe. Thus,
whilst China had 91% of the global number of cases it is believed
that it has 95% of the YLLs due to alveolar echinococcosis. The
total number of DALYs per annum for the world is estimated at a
median of 666,433 (CIs 331,539 – 1.3 million).
Discussion
This report represents a first attempt to estimate the global
burden of AE although the global geographical distribution of E.
multilocularis has been reviewed previously (e.g. [2]). Throughout
much of its geographical range AE is sporadic in humans. In high
income countries such as Germany and Switzerland the numbers
of cases were the actual number reported (Switzerland) [5].
Alternatively in Germanyreported figures were based on a
reported capture recapture technique which modelled underre-
porting [13]. These are believed to be accurate reports of the
numbers of cases. Reviews of published data also gave estimates
for a number of other upper income countries.
For some lower income studies there was limited official data
(unpublished) reporting the total number of cases presenting for
treatment. However in such countries a major underestimation of
the numbers of cases is possible as only relatively wealthy
individuals can pay for medical care and the majority of cases
may not present for treatment and hence go undiagnosed. A
criticism of our approach is that we did not use consistent inclusion
criteria for data in different countries. What we did use was the
best available data and balanced this inconsistency by using a
stochastic approach to model uncertainty. In the countries where
we believed the data was accurate a very narrow probability
distribution was chosen for the Monte-Carlo routine. In contrast
where there was poor data, a very wide distribution was used to
model this uncertainty. Hence, the median incidence and
estimated DALYs together with the 95% confidence limits give
a good estimate of the burden of AE.
In certain districts of China several studies have indicated a very
high prevalence of AE through mass screening studies. Surveys
have consistently shown a high prevalence of AE using ultrasound
studies across Sichuan, Gansu, Qinghai, and Ninxia (Table 2).
This confirms that there are large numbers of AE cases in China
and these represent at least 91% of the global incidence. In some
communities the prevalence of AE is similar to that of tuberculosis
[23]. Because of the large population at risk and the consistent
finding of high prevalences we believe the estimate of the number
of cases in China is representative. However, the prevalence is not
uniform with variations within these districts of between ,1% to
12%. The calculations have tried to accommodate these variations
in arriving at an overall incidence figure. In the Tibet Autonomous
Region (TAR), the incidence could be much higher than the
Table 1. Countries believed to be endemic for E.
multilocularis over at least part of their territory.
Europe Asia North America
Austria Afghanistan Canada
Belgium Armenia USA
Belorussia Azerbaijan
Bulgaria Bhutan
Croatia China
Czech Republic Georgia
Denmark India
Estonia Iran
France Iraq
FYR Macedonia Japan
Germany Kazakhstan
Greece Kyrgyzstan
Hungary Nepal
Italy Mongolia
Kosovo Pakistan
Latvia Russia*
Liechtenstein Tajikistan
Lithuania Turkey
Luxembourg Turkmenistan
Moldova Uzbekistan
Montenegro
Netherlands
Poland
Rumania
Russia*
Serbia
Slovakia
Slovenia
Switzerland
Ukraine
*Both European and Asian parts of Russia include large endemic areas.
doi:10.1371/journal.pntd.0000722.t001
Table 2. Population studies for AE in rural China.
Region
Number
with AE
Population
size studied Reference
Ningxia (Xija, Guyuan and Haiyuan
counties
96 4778 [51]
Sichuan (Ganzu autonomous
prefecture)
308 8512 [52]
Gansu (Dingxi prefecture) 114 3836 [53]
Qinghai 39 1549 [54]
Sichuan 60 705 [55]
Gansu 84 2482 [56]
Gansu (Ming and Zhang counties) 86 2485 [57]
Qinghai (Zhiduo County) 2 979 [58]
Qinghai (Chindu, Zeko and Gade
counties)
31 3703 [59]
Sichuan (Ganzi and Shiqu counties) 223 7138 [12]
Ningxia Hui Autonomous
Region (Xiji County)
20 221 [60]
*Total 1063 36388 2.9%
+Gansu (Zhang county) 65 1312 [6]
*Total of studies in the last 10 years.
+Study from 1992.
doi:10.1371/journal.pntd.0000722.t002
Burden of Alveolar Echinococcosis
www.plosntds.org 5 June 2010 | Volume 4 | Issue 6 | e722
figures suggested. Tibetan communities in neighbouring districts
of Sichuan for example have very high prevalences. The parasite is
known to be endemic in TAR, but there is no published human
surveillance data. We were only able to assume that prevalences in
the eastern most part of TAR were similar to prevalences in
neighbouring counties of Sichuan or Qinghai. It is possible,
therefore, that the true incidence could be thousands rather than
the hundreds that are suggested. There is a single case report of
cerebral AE in a Tibetan monk who originated from Lhasa which
is quite some distance west of the known highly endemic areas of
Gansu, Qinghai, and Sichaun [24] which is evidence that the
parasite has a greater range than our conservative assumption. In
Xingjiang the parasite is endemic, but human studies have mainly
uncovered cases along the northwest of the province and hence the
population at risk and actual case numbers are calculated
accordingly.
Table 3. The relative numbers of CE:AE cases in various
studies from Turkey.
Number of CE Number of AE Reference
44 6 [61]
72 8 [62]
196 47 [63]
109 39 [64]
203 16 [17]*
336 11 [17]**
138 20 [65]
111 22 [66]
*Intracranial echinococcosis only. Case searching from 47 neurosurgical units
between 1994 and 1999.
**Intracranial echinococcosis only. Reported literature cases from Turkey from
1940s–1990s.
doi:10.1371/journal.pntd.0000722.t003
Table 4. Published case report series from Russia.
Number of CE Number of AE Reference
48 24 [67]
95 40 [68]
44 84 [27]*
*These data are from districts of Siberia where AE relative incidence might be
expected to be higher.
doi:10.1371/journal.pntd.0000722.t004
Figure 3. Flow chart illustrating the search methods and processing of information.
doi:10.1371/journal.pntd.0000722.g003
Burden of Alveolar Echinococcosis
www.plosntds.org 6 June 2010 | Volume 4 | Issue 6 | e722
Russia is a large endemic area for alveolar echinococcosis. In
some districts, particularly in Siberia there are reports of a number
of human cases whilst elsewhere the disease is sporadic. Detailed
data is somewhat lacking despite intensive search of English and
Russian language databases. Most data is reported in terms of
hospital reports and is therefore estimated as an annual incidence.
There are no mass ultrasound surveillance studies as in China
although there are a few mass serological studies which tend to
confirm the potential for large numbers of cases, especially in
Siberia. It is clear, however, that the disease occurs sporadically
across almost the entire country. Even in districts where there are
no reported human cases there are reports of the parasite in
animal hosts so transmission to humans is likely. The estimates for
the whole of Russia initially relied on extrapolating data from
districts where there were known reports or unpublished data.
Bassonov wrote an extensive monograph [25] detailing the
epidemiology of echinococcosis throughout countries of the former
Soviet Union including summaries of otherwise difficult to obtain
material. This was also used as a basis for estimating the numbers
of cases in Russia. In addition, we were able to access some local
Russian language reports including articles in local newspapers
and these largely confirmed our assumptions [26]. Estimates based
on the samples from case series (essentially a type of capture
recapture technique) described in the text tended to confirm these
estimates. We assumed a maximum ratio of 1:2 for AE:CE.
However, one study of surgical cases from Omsk in western
Siberia described 84 cases of AE and 44 cases of CE [27]. As most
of these cases were from Siberian districts such as Kemerova,
Altai, Yakutia and Tomsk which could indicate higher numbers of
AE than the ratios we used in our calculations.
Table 5. Estimated annual numbers of new cases in endemic
provinces of China.
Chinese
province
Population
at risk
Estimated
prevalence
Estimated median
number of new
cases per year
Gansu 3.6 million 2.9% 7676
Inner Mongolia 3 million 0.02% 44
Qinghai 5.4 million 1.0% 3766
Ningxia 1.2 million 2.0% 1770
Sichuan 0.92 million 3.6% 2390
Tibet Autono-
mous Region
2.7 million 0.1% 172
Xinjiang 5.8 million 0.2% 811
doi:10.1371/journal.pntd.0000722.t005
Table 6. Estimated annual incidence of AE in Asia, by
country.
Country
Estimated
Number of Cases
Afghanistan 1 Single case report [31]
Armenia 3 Estimated
Azerbaijan 6 Estimated
Bhutan ,1 No data
China 16,629 See table 5
Georgia 6 Estimated
India 1 Two case reports [29,30]
Iran 11 Estimated
Iraq 1 Single case report [33]
Japan 12 Reported cases [69]
Kazakhstan 39 Estimated
Kyrgyztan 17 Actual figures (unpublished)
Mongolia 9 Actual figures (unpublished)
Nepal ,1 No data
Pakistan ,1 No data
Russia* 1180 See text
Tajikistan 20 Estimated
Turkmenistan 2 Estimated
Turkey 100 Estimated and modelled from
various data (see text)
Uzbekistan 24 Estimated
*Including European Russia.
doi:10.1371/journal.pntd.0000722.t006
Table 7. Estimated median annual numbers of cases from
Eastern Europe.
Country
Estimated annual
number of cases Source
Belorussia 6 Border districts of Lithuania have
cases
Bulgaria 1 Estimated
Czech republic 1 Estimated
Estonia 9 Similar to Lithuania
Greece 1 1 case reported from 1980 to 2000
[70]
Hungary 1 First case reported 2004 [71]
Latvia 9 Similar to Lithuania
Lithuania 9 Reported cases [40]
Macedonia 1 One case reported in 10 years [72]
Moldova 1 Estimated
Poland 3 1992–2007, 45 cases recorded [73]
Slovakia 4 Four cases in 2007 [74]
Slovenia 2 0.45 per 100,000 over 5 years [75]
Ukraine 10 Estimated. Endemic [25]
doi:10.1371/journal.pntd.0000722.t007
Table 8. Estimated annual numbers of cases of AE in Central
and Western Europe.
Country
Estimated annual
number of cases Reference
Austria 7 [19,76]
Belgium 1 [19,77]
France 21 [68]
Germany 61 [78]
Switzerland 20 [3,5]
doi:10.1371/journal.pntd.0000722.t008
Burden of Alveolar Echinococcosis
www.plosntds.org 7 June 2010 | Volume 4 | Issue 6 | e722
The mountainous regions of Kazakhstan, Kyrgystan, Uzbeki-
stan, and Tadjikistan are all endemic for E. multilocularis [28]. Here
the cycle of infection has been well described in terms of the
animal hosts. The most accurate figures available are from
Kyrgyzstan where approximately 35 cases per years are now being
reported in the hospitals (unpublished figures from the Govern-
ment Epidemiological Surveillance Unit, Bishkek). This figure is
likely to be accurate in terms of numbers being treated. However,
it may underestimate the actual numbers of cases occurring as the
country is poor and expensive medical treatment is not available to
a large part of the population.
Although ethnically distinct, in terms of geography and
economy, Tadjikistan is very similar to Kyrgyzstan. Therefore,
as it is also endemic for E. multilocularis, similar numbers of cases
per year could be expected as there is likely a similar population
size at risk. Kazakhstan and Uzebkistan are much larger countries
in area and population but as much of their territory is in low or
non-endemic areas the proportion of population at risk is smaller,
but absolute numbers are similar. Turkmenistan is likely to have
few cases of AE, as much of the territory is arid desert which is
inimical to transmission. Mongolia has a number of reported
cases. From unpublished data there were 9 cases of AE in both
2006 and 2007.
India, Nepal, Bhutan and Pakistan border on endemic zones
and may have a few cases. The disease has been reported in India
(Kashmir) [29,30]. For Afghanistan, data is not available.
However there is a case report of a patient originating from
Afghanistan who was treated in the UK (which is non endemic)
[31]. Therefore, further cases are likely, especially in the north of
the country. Iran is endemic for AE but there is little data.
Between 1948 and 1993, 37 cases of AE were reported [32] or less
than 1 case per year. In view of the fact that neighbouring Turkey
is known to be highly endemic this is likely underreported. There is
a single case report of AE from northern Iraq [33].
Turkey is highly endemic for echinococcosis. In total,
approximately 3000 cases are recorded annually. The number of
cases of AE is uncertain. The proportion of cases of echinococcosis
that are AE have been reported in a number of case series
(Table 3). Assuming a similar ratio of AE to CE nationwide as
found in the case report series this would suggest as many as 500
cases of AE per year. However, such selected case series may
overestimate the true incidence of AE and these data contrast
somewhat with the report of 206 cases of AE in Turkey for the
period 1980–2000 or just 10 cases per year [34]. AE has only
recently been made reportable in Turkey [16] and so more
accurate figures are unavailable. Also of interest is a case finding
study which specifically searched through the records of 47
neurosurgical units for cases of cerebral echinococcosis. This study
found a total of 219 cases of intracranial echinococcosis in the five
year period 1994–1999 [17]. Of these 16 were AE and 2 were AE
with no extra CNS involvement. Another report found 4 CNS
cases of AE in just 27 months at one centre [35]. Intracranial AE is
thought to be rare with CNS involvement usually a manifestation
of metastases from a primary lesion. A large study in China
suggested that 4% of AE cases had neurological involvement [18].
Likewise, a large European study found 17 of 559 (3%) cases of AE
had brain involvement [19]. The incidence of diagnosed
intracranial cases of AE therefore gives strong evidence there
must be at least 100 cases of AE per year in Turkey. This type of
approach may, nevertheless, substantially underestimate AE cases
in resource poor endemic regions, as a smaller proportion of AE
cases my receive hospital treatment then are actually present in the
community. For example, in south Ningxi in China, CE
represented 96% of hospital treated cases of echinococcosis, but
ultrasound studies in the local community suggest that 56% of
cases of echinococcosis are AE [36].
The USA and Canada are endemic for E. multilocularis.
However there is very little transmission to man. There have
been reports from Native American communities of high incidence
rates in Alaska [37] but only locally and these have been
eliminated by appropriate intervention programs. Otherwise,
there have only been single cases reports in Minnesota [38] and
Manitoba [39]. Thus there is very little evidence for autochtho-
nous human cases presently in North America despite the active
transmission in animal hosts.
Eastern Europe has highly variable data. The parasite is
endemic in most of the former Soviet States. Lithuania has the best
data and reports incidence rates [40] and it is likely that the other
Baltic States have similar incidences due to similarities in culture,
geography, and population. From central and western Europe
there is usually high quality data giving details of the numbers of
cases (Table 7). The core endemic area is centred on Switzerland,
southern Germany, and eastern France.
In North Africa, there have been two reports of autochthonous
AE from Tunisia and a further case from Morocco diagnosed by
histological examination of the lesions [41,42]. However the
parasite has never been recorded in animals from Africa and in the
absence of molecular confirmation there is insufficient evidence to
confirm any part of North Africa is presently endemic for E.
multilocularis.
AE is a serious disease and, although the prognosis is reasonably
good when treatment is available [3], the prognosis is equally bleak
in the absence of treatment. The overwhelming number of cases
comes from an area of rural China which forms part of the
Tibetan plateau. This population is remote and with few financial
resources with an estimated annual income per head of less than
US$500 [43]. Therefore it is reasonable to assume that most of
these cases will be fatal and hence, the annual mortality due to AE
is similar to the incidence. This is also likely to be true of most
other cases outside of Europe. An annual mortality due to AE of
approximately 18,000 is greater than one tenth of the total
mortality of 177,000 as a result of the 10 diseases of the neglected
tropical disease cluster (trypanosomiasis, Chagas disease, schisto-
somiasis, leishmaniasis, lymphatic filariasis, onchocerciasis, intes-
tinal nematode infections, Japanese encephalitis, dengue, and
leprosy ) [44]. The disease burden can also be compared to that of
rabies. Annual AE mortality is approximately one third of that due
to rabies which has been estimated at approximately 55,000
[45,46]. Nearly all is from Africa and Asia. Unlike rabies, there is
also no vaccine for canid echinococcosis and control requires
repeated treatment of foxes or dogs with praziquantel. Thus,
although AE is rare on a global scale it has a high burden in some
highly endemic communities in China where it is likely to be one
of the leading causes of death.
Likewise the global burden of disease, in terms of DALYs, is
high. This is again due to the very high fatality rate resulting in a
large number of YLLs but additionally due to the expected high
disability weight that individuals have during the course of the
disease. Diseases with similar magnitudes of DALYs include
neglected tropical diseases such as onchocerciasis, and Chagas
disease [47]. An initial estimate of the global burden of cystic
echinococcosis was approximately 1 million DALYs [22].
However, this is likely to be an underestimate [48] and a re-
evaluation of the global burden of CE is ongoing.
Control of this disease depends on the risk factors for
transmission. The wild life cycle can be disturbed through the
treatment of foxes with praziquantel impregnated baits [10].
However, the feasibility of applying such control measures over
Burden of Alveolar Echinococcosis
www.plosntds.org 8 June 2010 | Volume 4 | Issue 6 | e722
large parts of the Tibetan plateau, where the main burden of AE is
found, would be questionable. Dog contact is a known risk factor
for transmission to man [49] and dogs are highly susceptible to
infection with this parasite [50]. However, it is not known if dogs
participate in the cycle or are aberrant definitive hosts. If they are
aberrant hosts, periodic treatment of dogs will not disturb the
transmission cycle and will have much less effect on long term
transmission rates to humans [43]. Other means of reducing the
disease burden would be through better control of food or water
supplies which may be contaminated with parasite eggs. Such
control would be dependent on the attributable fraction of disease
burden due to these transmission pathways and the cost
effectiveness of such intervention strategies.
Author Contributions
Conceived and designed the experiments: PRT. Analyzed the data: PRT
KK MM NR. Contributed reagents/materials/analysis tools: PRT KK
MM NR. Wrote the paper: PRT. Constructed database: KK MM NR.
References
1. Torgerson PR, Budke CM (2003) Echinococcosis - an international public health
challenge. Res Vet Sci 74: 191–202.
2. Eckert J, Deplazes P (2004) Biological, epidemiological and clinical aspects of
echinococcosis: a zoonosis of increasing concern. Clin Microbiol Rev 17:
107–135.
3. Torgerson PR, Schweiger A, Deplazes P, Pohar M, Reichen J, et al. (2008)
Alveolar echinococcosis: from a deadly disease to a well controlled infection.
Relative survival and economic analysis in Switzerland over the last 35 years.
J Hepatology 49: 72–77.
4. Romig T, Dinkel A, Mackenstedt U (2006) The present situation of
echinococcosis in Europe. Parasitology Int 55: S187–S191.
5. Schweiger A, Ammann RW, Candinas D, Clavien P-A, Eckert J, et al. (2007)
Human alveolar echinococcosis after fox population increase, Switzerland.
Emerg Infec Dis 13: 878–882.
6. Craig PS, Deshan L, Macpherson CNL, Dazhong S, Reynolds D, et al. (1992) A
large focus of alveolar echinococcosis in central China. Lancet 340: 826–831.
7. Budke CM, Jiamin Q, Zinsstag J, Qian W, Torgerson PR (2004) Use of disability
adjusted life years in the estimation of the disease burden of echinococcosis for a
high endemic region of the Tibetan plateau. Am J Trop Med Hyg 71: 56–64.
8. Budke CM, Campos-Ponce M, Qian W, Torgerson PR (2005) A canine
purgation study and risk factor analysis for echinococcosis in a high endemic
region of the Tibetan plateau. Vet Parasitol 127: 43–49.
9. Ziadinov I, Mathis A, Trachsel D, Rysmukhambetova AT, Abdyjaparov TA,
et al. (2008) Canine echinococcosis in Kyrgyzstan: epidemiology and
transmission analysis incorporting diagnostic uncertainty. Int J Parasitol 38:
1179–1190.
10. Heglin D, Deplazes P (2008) Control strategy for Echinococcus multilocularis. Emerg
Infect Dis 14: 1626–1628.
11. Kern PA, Kron M, Sinn G, Sander S, Petersen LR, et al. (2004) Risk factors for
alveolar echinococcosis in humans. Emerg Infect Dis 10: 2088–2093.
12. Wang Q, Qiu J, Schantz PM, Raoul F, Craig PS, et al. (2006) Socioeconomic
behavior risk factors of human alveolar echinococcosis in Tibetan communities
in Sichuan, People’s Republic of China. Am J Trop Med Hyg 74: 856–862.
13. Jorgensen P, an der Heiden M, Kern P, Scho¨ neberg I, Krause G, et al. (2008)
Underreporting of human alveolar echinococcosis, Germany. Emerg Infect Dis
14: 935–937.
14. Bishnevski AA, Koroleva NS, Bishevskaya GA (2007) The protocol of the 244th
session of the pulmonary section of the surgical society of Moscow and Moscow
Oblast - 11.04.06. Problems of Tuberculosis and Lung Diseases 2: 61–64. [In
Russian].
15. Yazar S, Taylan Ozkan A, Hokelek M, Polat E, Yilmaz H, et al. (2008) Cystic
echinococcosis in Turkey from 2001–2005. Turkish Journal of Parasitology 32:
208–220.
16. Altintas N (2008) Parasitic zoonoses diseases in Turkey. Veterinaria Italiana 44:
633–646.
17. Altinors N, Bavbek M, Caner HH, Erdogan B (2000) Central nervous system
hydatidosis in Turkey: a cooperative study and literature survey analysis of 458
cases. J Neurosurg 93: 1–8.
18. Jiang P, McManus DP, Jones M (2005) Liver alveolar echinococcosis in China:
clinical aspect with relative basic research. World J Gastroenterology 11:
4611–4617.
19. Kern P, Bardonnet K, Renner E, Auer H, Pawlowski Z, et al. (2003) European
echinococcosis registry: human alveolar echinococcosis, Europe, 1982–2000.
Emerg Infect Dis 9: 343–349.
20. Murray CJL (1994) Quantifying the burden of disease: the technical basis for
disability-adjusted life years. Bull WHO 72: 429–445.
21. Anonymous (2004) Global burden of disease 2004 update: disability weights for
diseases and conditions Geneva WHO.
22. Budke CM, Deplazes P, Torgerson PR (2006) Global socioeconomic impact of
cystic echinococcosis. Emerg Infect Dis 12: 296–303.
23. Yang YR, Gray DJ, Ellis MK, Yang SK, Craig PS, et al. (2009) Human cases of
simultaneous echinococcosis and tuberculosis - significance and extent in China.
Parasites and Vectors 2: 53. doi:10.1186/1756-3305-2-53.
24. Tappe T, Weise D, Ziegler U, Mu¨ ller A, Mu¨llges W, et al. (2008) Brain and lung
metastasis of alveolar echinococcosis in a refugee from a hyperend emic area.
J Medical Microbiol 57: 1420–1423.
25. Bessonov AS (2003) Alveolar echinococcosis and hydatidosis Moscow Russian
Academy. 334 p. [in Russian].
26. Stepchuk MA, Polosmak LP (1991) The prevention of alveolar hydatid disease in
the Koryak Autonomous Okrug Medical Parasitology (Moscow). pp 45–46. [in
Russian].
27. Alperovich BI, Merzlikin NV, Salo VN (2006) Materials of the regional scientific
and practical seminar ‘‘Contempory aspects of surgical treatment of malignant
tumours of the hepatic-duodenum zone’’. Cryosurgery of maliganant and
parasitic disease of the liver. Siberian Oncology Journal 1: 36–39. [in Russ ian].
28. Shaikenov BS (2006) Distribution and ecology of Echinococcus multiloculari s in
Central Asia. Parasitology Int 55: S213–S219.
29. Aikat BK, Bhusnurmath SR, Cadersa M, Chhuttani PN, Mitra SK (1978)
Echinococcus multilocoularis infection in India: first case report proved at autopsy.
Trans Royal Soc Trop Med Hyg 72: 619–621.
30. Khuroo MS, Datta DV, Khoshy A, Mitra SK, Chhuttani PN (1980) Alveolar
hydatid disease of the liver with Budd-Chiari syndrome. Postgrad Med J 56:
197–201.
31. Graham JC, Gunn M, Hudson M, Orr KE, Craig PS (2002) A mass in the liver.
J Infection 45: 121–122.
32. Rokni MB (2008) The present state of human helminthic diseases in Iran. Ann
Trop Med Parasitol 102: 283–295.
33. Al-Attar HK, Al-Irhayin B, Al-Habbal MJ (1983) Alveola r hydatid disease of
the liver: first case report from man in Iraq. Ann Trop Med Parasitol 77:
595–597.
34. Uzunlar AK, Yilmaz F, Bitiren M (2003) Echinococcosis multilocularis in south-
eastern Anatolia, Turkey. East African Med J 80: 395–397.
35. Aydin Y, Barlas O, Yolas C, Aydin IH, Ceviz A, et al. (1986) Alveolar hydatid
disease of the brain. Report of four cases. J Neurosurgery 65: 115–119.
36. Yang YR, Williams GM, Craig PS, Sun T, Yang SK, et al. (2006) Hospital and
community surveys reveal the severe public health problem and socio-economic
impact of human echinococcosis in Ningxia Hui Autonomous Region, China.
Trop Med Int Health 11: 880–888.
37. Wilson JF, Rausch RL (1980) Alveolar hydatid disease. A review of clinical
features of 33 indigenous cases of Echinococcus multilocularis infection in Alaskan
Eskimos. Am J Trop Med Hyg 29: 1340–1355.
38. Gamble WG, Segal M, Schantz PM, Rausch RL (1979) Alveolar hydatid disease
in Minnesota. First human case acquired in the contiguous United States. JAMA
241: 904–907.
39. James E, Boyd W (1937) Echinococcus alveolaris. Can Med Assoc J 36: 354–356.
40. Bruzinskaite R, Marcinkute A, Strupas K, Sokolova V, Deplazes P, et al. (2007)
Alveolar echinococcosis, Lithuania. Emerg Infect Dis 13: 1618–1619.
41. Zitouna MM, Boubaker S, Dellagi K, Ben Safta Z, Hadj Salah H, et al. (1985)
Alveolar echinococcosis in Tunisia. Apropos of 2 cases. Bull Soc Pathol Exot
Filiales 78: 723–728. [in French].
42. Maliki M, Mansouri F, Bouhamidi B, Nabih N, Bernoussi Z, et al. (2004)
Hepatic alveolar hydatidosis in Morocco. Med Trop (Mars) 64: 379–380. [in
French].
43. Budke CM, Jiamin Q, Qian W, Torgerson PR (2005) Economic effects of
echinococcosis in a disease-endemic region of the Tibetan Plateau. Am J Trop
Med Hyg 73: 2–10.
44. Mathers CD, Ezzati M, Lopez AD (2007) Measuring the burden of neglected
tropical diseases: the global burden of disease framework. PLoS Negl Trop Dis 7:
1(2): e114.
45. Knobel DL, Cleaveland S, Coleman PG, Fevre EM, Meltzer MI, et al. (2005)
Re-evaluating the burden of rabies in Africa and Asia. Bull WHO 83: 360–
368.
46. WHO (2005) WHO Expert Consultation on Rabies. Geneva: WHO.
47. WHO (2004) The World Health Report - Changing History. Geneva: WHO. pp
157.
48. Craig PS, Budke CM, Schantz PM, Tiaoying L, Qiu J, et al. (2007) Human
echinococcosis: a neglected disease? Trop Med Health 35: 283–292.
49. Craig PS (2006) Epidemiology of human alveolar echinococcosis in China.
Parasitology Int 55: S221–S225.
50. Kapel CMO, Torgerson PR, Thompson RCA, Deplazes P (2006) Reproductive
potential of Echinococcus multilocularis in experimentally infected foxes, dogs,
raccoon dogs and cats. Int J Parasitol 36: 79–86.
Burden of Alveolar Echinococcosis
www.plosntds.org 9 June 2010 | Volume 4 | Issue 6 | e722
51. Yang YR, Craig PS, Ito A, Vuitton DA, Giraudoux P, et al. (2007) A correlative
study of ultrasound with serology in an area in China co-endemic for human
alveolar and cystic echinococcosis. Trop Med Int Health 12: 637–646.
52. Tiaoying L, Jiamin Q, Wen Y, Craig PS, Xingwang C , et al. (2005)
Echinococcosis in Tibetan populations, western Sichuan Province, China.
Emerg Infect Dis 11: 1866–1873.
53. Dazhong SHI, Wenke LI, Genshu BAO (2003) Approach to risk factor of
human behavior on epidemic of alveolar echinococcosis. Chinese J Public
Health 19: 973–974.
54. Yu SH, Wang H, Wu XH, Ma X, Liu PY, et al. (2008) Cystic and Alveolar
echinococcosis: an epidemiological survey in a Tibetan population in Southeast
Qinghai, China. Japanese J Infec Dis 61: 242–246.
55. Wang Q, Vuitton DA, Qiu JM, Giraudoux P, Xiao YF, et al. (2004) Fenced
pasture: a possible risk factor for human alveolar echinococcosis in Tibetan
pastoralist communities of Sichuan, China. Acta Trop 90: 285–293.
56. Bartholomot G, Vuitton DA, Harraga S, Shi DZ, Giraudoux P, et al. (2002)
Combined ultrasound and serologic screening for hepatic alveolar echinococ-
cosis in central China. Am J Trop Med Hyg 66: 23–29.
57. Shi D, Li W, Bao G (2003) Approach to risk factor of human behavior on
epidemic of alveolar echinococcosis. Chinese J Public Health 19: 973–974.
58. Wu X, Wang H, Zhang J, Ma X, Liu Y, et al. (2006) An epidemiological survey
on echinococcosis in Zhidua County of Qinghai Province. Chinese J Parasitic
Dis 25: 229–231.
59. Schantz PM, Wang H, Qiu J, Liu FJ, Saito E, et al. (2003) Echinococcosis on the
Tibetan Plateau: prevalence and risk factors for cystic and alveolar echinococ-
cosis in Tibetan populations in Qinghai Province, China. Parasitology 127:
S109–S120.
60. Yang YR, Ellis MK, Sun T, Li Z, Liu X, et al. (2006) Unique family clustering of
human echinococcosis cases in a Chinese community. Am J Trop Med Hyg 74:
487–494.
61. Canda MS (1995) The pathology of echinococcosis (50 cases) and the current
echinococcus problem of Turkey. Turkish Journal of Ecopathology 1: 55–58. [in
Turkish].
62. Canda MS, Guray M, Canda T, Astarcioglu H (2003) The pathology of
echinococcosis and the current echinococcosis problem in Western Turkey (a
report of pathological features of 80 cases). Turkish Journal of Medical Sciences
33: 369–374.
63. Kilinc N, Uzunlar AK, Ozaydin M (2003) Uncommonly localised cases of
echinococcosis (report of 45 cases). Turkish Journal of Ecopathology 9: 25–30.
[in Turkish].
64. Korkmaz M, Inceboz T, Celebi F, Babaoglu A, Uner A (2004) Use of two
sensitive and specific immunoblot markers, Em 80 and Em 90, for diagnosis of
alveolar echinococcosis. J Clin Microbiol 42: 3350–3352.
65. Temir YA, Ozaydin M, Muderriszade M, Yaldiz M, Hakverdi S (1995)
Problems of echinococcosis in the Diyarbakir Province (158 cases). Turkish
Journal of Ecopathology 1: 104–109. [in Turkish].
66. Gundogdu C, Arslan R, Arslan MO, Gicik Y (2005) Evaluation of cystic and
alveolar echinococcosis in people in Erzurum and surrounding cities. Acta
Parasitologica Turcica 29: 163–166. [in Turkish].
67. Lysenko MV (2006) Resction of the liver for focal lesions. Military Medical
Journal 7: 20–22. [in Russian].
68. Abdullaev AG, Shishlo LA, Adrianov SO, Rodionova TV (2006) Clinical and
laboratory symptoms of space-occupying hepatic lesions and their prognostic
value. Journal of Surgery in the Name of N I Pirogov. (www.mediasphera.ru/
journals/pirogov/detail/264/4007/) [in Russian].
69. Oku Y, Kamiya M (2003) Biology of Echinococcus. In: Otsuru M, Kamegai S,
Hayashi S, eds. Progress of Medical Parasitology in Japan. Tokyo: Meguro
Parasitological Museum. pp 293–318.
70. Vuitton DA, Zhou H, Bresson-Hadni S, Wang Q, Piarroux M, et al. (2003)
Epidemiology of alveolar echinococcosis with particular reference to China and
Europe. Parasitology 127: S87–S107.
71. Horva´ th A, Patonay A, Ba´nhegyi D, Szla´vik J, Bala´ zs G, et al. (2008) The first
case of human alveolar echinococcosis in Hungary. Orv Hetil 149: 795–796. [in
Hungarian].
72. Druschky KF, Niederstadt T, Jourdan W, Stoltze D, Heckl R (1995) High-grade
transverse syndrome caused by Echinococcus cysts. Nervenarzt 66: 136–139. [in
German].
73. Stefaniak J (2007) Guidelines for diagnosis and treatment of alveococcosis caused
by Echinococcus multilocularis. Wiad Parazytol 53: 189–194.
74. Kinc
ˇekova´J,Hrc
ˇkova´ G, Szabadosˇova´ V, Hudac
ˇkova´ J, Stanislayova´ M, et al.
(2007) Using PCR analysis for diagnosis of patients with hepatic alveolar
echinococcosis. Czech and Slovak Gastroenterology and Hepatology 61: 18–22.
75. Logar J, Soba B, Lejko-Zupanc T, Kotar T (2007) Human alveolar
echinococcosis in Slovenia. Clinical Microbiology and Infection 13: 544–546.
76. Auer H, Aspock H (2001) Human alveolar echinococcosis and cystic
echinococcosis in Austria: the recent epidemiological situation. Helminthologia
38: 3–14.
77. Wauter O, Honore C, Detry O, Delwaide J, Demonty J, et al. (2005)
L’echinococcose alveolaire: une zone d’apparition recente en Wallonie. Rev
Med Liege 60: 867–874.
78. Jorgensen P, an der Heiden M, Kern P, Scho¨ neberg I, Krause G, et al. (2008)
Underreporting of human alveolar echinococcosis, Germany. Emerg Infect Dis
14: 935–937.
Burden of Alveolar Echinococcosis
www.plosntds.org 10 June 2010 | Volume 4 | Issue 6 | e722
... Alveolar echinococcosis (AE) is the most lethal and has gradually become an emerging disease in recent years. About 18,000 new cases are added every year in the world, with an incidence rate of 0.03 to 1.2 per 100,000 in epidemic areas, mainly distributed in countries in the northern hemisphere, such as France, Germany, Switzerland, Austria and China, of which more than 90% occur in China [3][4][5]. AE has been ranked as the second most important food-borne parasitic disease worldwide by the Food and Agriculture Organization of the UN and WHO [6,7]. Notably, water could be a potential source of E. multilocularis infection in humans and animals in endemic areas [8,9]. ...
Article
Full-text available
Background This study was designed to investigate clinical efficiency and application indications of hepatic lobe hyperplasia techniques for advanced hepatic alveolar echinococcosis (AE) patients. Methods A retrospective case series covering 19 advanced hepatic AE patients admitted to the First Affiliated Hospital of Xinjiang Medical University from September 2014 to December 2021 and undergoing hepatic lobe hyperplasia techniques due to insufficient remnant liver volume were analyzed. Changes of liver function, lesions volume, remnant liver volume, total liver volume before and after operation have been observed. Results Among the patients, 15 underwent portal vein embolization (PVE). There was no statistical difference in total liver volume and lesions volume before and after PVE ( P > 0.05). However, the remnant liver volume was significantly increased after PVE ( P < 0.05). The median monthly increase rate in future liver remnant volume (FLRV) after PVE stood at 4.49% (IQR 3.55–7.06). Among the four patients undergoing two-stage hepatectomy (TSH), FLRV was larger than that before the first stage surgery, and the median monthly increase rate in FLRV after it stood at 3.34% (IQR 2.17–4.61). Despite no statistical difference in total bilirubin (TBil), albumin (Alb), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyl transpeptidase (GGT) in all patients with PVE, four patients who underwent TSH showed a decrease in ALT, AST and GGT. During the waiting process before the second stage operation, no serious complications occurred in all patients. Conclusions For patients suffering from advanced hepatic AE with insufficient FLRV, PVE and TSH are safe and feasible in promoting hepatic lobe hyperplasia.
... In fact, approximately 200 000 new cases per year of cystic echinococcosis and 18 000 new cases per year of alveolar echinococcosis are estimated globally, with 91% of alveolar echinococcosis cases occurring in China and around 1600 cases in Europe, central Asia, and Russia. 5,27,40,41 According to this numerical proportion, for every human alveolar echinococcosis infection, 10-20 cystic echinococcosis infections can be expected, particularly in Europe but also worldwide. Notably, even ...
Article
Full-text available
The neglected zoonosis cystic echinococcosis affects mainly pastoral and rural communities in both low-income and upper-middle-income countries. In Europe, it should be regarded as an orphan and rare disease. Although human cystic echinococcosis is a notifiable parasitic infectious disease in most European countries, in practice it is largely under-reported by national health systems. To fill this gap, we extracted data on the number, incidence, and trend of human cases in Europe through a systematic review approach, using both the scientific and grey literature and accounting for the period of publication from 1997 to 2021. The highest number of possible human cases at the national level was calculated from various data sources to generate a descriptive model of human cystic echinococcosis in Europe. We identified 64 745 human cystic echinococcosis cases from 40 European countries. The mean annual incidence from 1997 to 2020 throughout Europe was 0·64 cases per 100 000 people and in EU member states was 0·50 cases per 100 000 people. Based on incidence rates and trends detected in this study, the current epicentre of cystic echinococcosis in Europe is in the southeastern European countries, whereas historical endemic European Mediterranean countries have recorded a decrease in the number of cases over the time.
... [18,19] Although India is located in the northern hemisphere, there are only case reports of alveolar hydatid disease from India, [20][21][22] and incidence in India as calculated based on the case reports is 1 per year. [23] There have been no studies regarding the disease burden from India. Climatic and landscape conditions (areas with very cold winters and high annual rainfall levels) have been demonstrated to increase the risk of developing alveolar hydatid among humans. ...
... Human alveolar echinococcosis (AE) is a zoonotic disease caused by the metacestode stage of the tapeworm Echinococcus multilocularis and represents one of the most pathogenic zoonoses in the northern hemisphere (Kern et al., 2003). Transmission of E. multilocularis to humans is by ingestion of parasite eggs, either through direct contact with the definitive host or indirectly through the consumption of contaminated food or water (Torgerson et al., 2010). Considering the circulation of the parasite among the red fox population as an indicator of the epidemiological threat to humans, the monitoring of E. multilocularis in these animals is imperative (Oksanen et al., 2016). ...
Article
Full-text available
Echinococcus multilocularis has been spreading through Central Eastern Europe but has not yet been reported in Bosnia and Herzegovina (B&H). Recently, this parasite is confirmed in Croatia suggesting the movement of the parasite's distribution limit further south. Given that there is no surveillance or monitoring system for echinococcosis in B&H, our study was designed as a pilot study of E. multilocularis. A total of 57 red foxes originating from 24 localities all over the country were collected during the routine rabies monitoring, autopsied and examined for the presence of echinococcosis. Based on intestinal scraping technique and microscopy, E. multilocularis adult worms have been detected in one (1/57, 1.75%) red fox. To verify this finding and to differentiate Echinococcus spp., DNA extracted from adult worms was subjected to species-specific PCR targeting part of the mitochondrial 12S ribosomal RNA gene. E. multilocularis PCR-positive samples were further confirmed by NGS sequencing of a 203 bp amplified fragment of 12S rRNA, which has been deposited in GenBank (Accession no.: OP047920). This finding represents the first detection of E. multilocularis in B&H, strongly suggesting its presence in the country. The confirmation of the parasite in the same locality where migrants/refugees temporarily stay on their route to Western Europe highlights the need for a One Health approach in addressing all future questions. Moreover, the first detection of E. multilocularis in B&H warrants the need for the implementation of an appropriate state surveillance program.
... Humans are occasional intermediate hosts, and acquire the infection through ingestion of food and water contaminated with eggs expelled with the feces of canid species (2). The larval cells predominantly reside in the liver, progressively invade neighboring tissues and organs, and eventually lead to a nearly 90% mortality rate if remaining untreated (3,4). AE is becoming an emerging/re-emerging disease worldwide, mainly attributable to the lack of vaccines and active control measures (2,5). ...
Article
Full-text available
The cestode Echinococcus multilocularis larva infection causes lethal zoonotic alveolar echinococcosis (AE), a disease posing a great threat to the public health worldwide. This persistent hepatic tumor-like disease in AE patients has been largely attributed to aberrant T cell responses, of which Th1 responses are impeded, whilst Th2 and regulatory T cell responses are elevated, creating an immune tolerogenic microenvironment in the liver. However, the immune tolerance mechanisms are not fully understood. Dendritic cells (DCs) are key cellular components in facilitating immune tolerance in chronic diseases, including AE. Here, we demonstrate that indoleamine 2,3-dioxygenase 1-deficient (IDO1-/-) mice display less severe AE as compared to wild-type (WT) mice during the infection. Mechanistically, IDO1 prevents optimal T cells responses by programming DCs into a tolerogenic state. Specifically, IDO1 prevents the maturation and migration potential of DCs, as shown by the significantly enhanced expression of the antigen-presenting molecule (MHC II), costimulatory molecules (CD80 and CD86), and chemokine receptors (CXCR4 and CCR7) in infected IDO1-/- mice as compared to infected wild-type mice. More importantly, the tolerogenic phenotype of DCs is partly reverted in IDO1-/- mice, as indicated by enhanced activation, proliferation, and differentiation of both CD4+ and CD8+ - T cells upon infection with Echinococcus multilocularis, in comparison with WT mice. Interestingly, in absence of IDO1, CD4+ T cells are prone to differentiate to effector memory cells (CD44+CD62L-); in contrast, CD8+ T cells are highly biased to the central memory phenotype (CD44+CD62L+). Overall, these data are the first to demonstrate the essential role of IDO1 signaling in inducing immunosuppression in mice infected with Echinococcus multilocularis.
... To date, there are few studies regarding the nonmonetary burden and cost of AE. Torgerson et al. estimated that there are 18,200 new AE cases in China each year and calculated the nonmonetary burden using DALY (disability-adjusted life years) based on these numbers to be a median of 666,434 DALYs lost per year [17]. A recent study conducted by Lötsch et al. calculated the annual cost of AE to be EUR 680,000 in Austria alone [18]. ...
Article
Full-text available
Alveolar echinococcosis (AE) is a rare disease caused by Echinococcosis multilocularis, which usually requires multidisciplinary management including surgery as the only curative approach. In recent years, minimally invasive strategies have been increasingly adopted for liver surgery. In particular, robotic surgery enables surgeons to perform even complex liver resections using a minimally invasive approach. However, there are only a few reports on robotic liver surgery for AE. Consecutive patients undergoing robotic liver surgery for AE were analysed based on the prospective database of the Interdisciplinary Robotic Centre of Ulm University Hospital. Between January 2021 and August 2022, a total of 16 patients with AE underwent robotic hepatectomy at our institution. Median age was 55.5 years (23–73), median body mass index (BMI) was 25.8 kg/m2 (20.2–36.8) and 12 patients (75%) were female. Anatomic resections were performed in 14 patients (87.5%), of which 4 patients (25%) underwent major hepatectomies (i.e., resection of >3 segments) including two right hemihepatectomies, one left hemihepatectomy and one extended right hemihepatectomy performed as associating liver partition with portal vein ligation staged (ALPPS) hepatectomy. There was no 90-day mortality, no postoperative bile leakage and no posthepatectomy haemorrhage. One patient developed posthepatectomy liver failure grade B after extended right hemihepatectomy using an ALPPS approach. One patient had to be converted to open surgery and developed an organ-space surgical site infection, for which he was re-admitted and underwent intravenous antibiotic therapy. Median length of postoperative hospital stay was 7 days (4–30). To our knowledge, this is the largest series of robotic liver surgeries for AE. The robotic approach seems safe with promising short-term outcomes in this selected cohort for both minor as well as major resections.
... CE in China accounts for 40% of the disease burden worldwide, with as much as 398,000 disability-adjusted life years (DALYs) [12]. AE in China accounts for 90% of total cases and 91% of new cases worldwide [13]. ...
Article
Full-text available
Background Echinococcosis is a parasitic zoonotic disease that threatens human health and economic development. In China, 370 counties are endemic for echinococcosis. Qinghai-Tibet Plateau has the most patients and people at risk. Therefore, analyzing the societal factors related to susceptibility to the disease is critical for efficient prevention and control of echinococcosis. Methods The demographic characteristics and lifestyle of echinococcosis cases were clustered using K-means cluster analysis to determine the main factors of risk of echinococcosis. Results Middle-aged and young people as well as those with a low education level and herdsmen are at risk of contracting echinococcosis. Nomadism, domestic and feral dogs in the surrounding environment, and drinking heavily polluted natural surface water are the main behavioral risk factors. The cystic echinococcosis (CE) and alveolar echinococcosis (AE) cluster analysis focused on female, middle-aged, and young people, winter settlement and summer nomadism, and domestic and feral dogs in the surrounding environment. There were significant differences in lifestyle between Qinghai-Tibet Plateau cases and non-Qinghai-Tibet-Plateau cases. Conclusion According to the distribution of cases and CE and AE, this study identified the factors of risk of echinococcosis in the Qinghai-Tibet Plateau and non-Qinghai-Tibet Plateau. Adapted control techniques appropriate for the various epidemic areas should be established to serve as a reference for echinococcosis prevention. Graphical Abstract
Article
Objectives: 7T small animal magnetic resonance imaging (MRI) was used to analyze the growth characteristics of hepatic alveolar echinococcosis (HAE). Methods: A mouse model of HAE was established by intraperitoneal injection of alveolar Echinococcus tissue suspension. Ten mouse models successfully inoculated by ultrasound screening were selected. The mouse model was scanned with T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), and diffusion-weighted imaging (DWI) sequence by 7T small animal MRI. Size, morphology, boundary, signal, and relationship with surrounding tissues of the lesions were recorded as characteristic alterations. Mice were killed at the end of the experiment, and the pathological specimens were taken for routine hematoxylin and eosin staining. Results: Lesions were mainly located in the right lobe of the liver. The multivesicular structure is the characteristic manifestation of this disease. In the liver, lesions invaded the portal vein and were mainly distributed at the hepatic hilum. The left branch of the portal vein was mainly invaded. The mean diameter of the lesions in the left lobe of the liver was larger than in other parts of the liver. The mean diameter of the cystic solid lesions was greater than the multilocular cystic lesions. HAE showed hypointense on T1WI, hyperintense on T2WI, and hypointense on DWI; the marginal zone of the lesion showed hyperintensity on DWI and grew toward the hilum. The MRI features of intraperitoneal lesions were similar to those of intrahepatic lesions. Intraperitoneal lesions increased faster than intrahepatic lesions in the same period. Conclusion: Polyvesicular structure is a characteristic manifestation of hepatic alveolar echinococcosis in mice. The noninvasive monitoring of liver HAE in mice by 7T small animal MRI provides a visual basis for the diagnosis and treatment integration of HAE.
Article
Human alveolar echinococcosis (AE) is a tumor-like disease predominantly located in the liver. The cellular composition and heterogeneity of the lesion-infiltrating lymphocytes which produce an "immunosuppressive" microenvironment are poorly understood. Here, we profiled 83,921 CD45+ lymphocytes isolated from the peripheral blood (PB), perilesion (PL), and adjacent normal (AN) liver tissue of four advanced-stage AE patients using single-cell RNA and T-cell receptor (TCR) sequencing technology. We identified 23 large clusters, and the distributions and transcriptomes of these cell clusters in the liver and periphery were different. The cellular proportions of exhausted CD8+ T cells and group 2 innate lymphoid cells (ILC2s) were notably higher in PL tissue, and the expression features of these cell subsets were related to neoplasm metastasis and immune response suppression. In the 5 CD8+ T-cell populations, only CD8+ mucosa-associated invariant T (MAIT) cells were enriched in PL samples and the TRAV1-2_TRAJ33_TRAC TCR was clonally expanded. In the 11 subsets of CD4+ T cells, Th17 cells and induced regulatory T cells (iTregs) were preferentially enriched in PL samples, and their highly expressed genes were related to cell invasion, tumor metastasis, and inhibition of the inflammatory immune response. Exhaustion-specific genes (TIGIT, PD-1, and CTLA4) were upregulated in Tregs. Interestingly, there was a close contact between CD8+ T cells and iTregs or Th17 cells, especially for genes related to immunosuppression, such as PDCD1-FAM3C, which were highly expressed in PL tissue. This transcriptional data set provides valuable insights and a rich resource for deeply understanding the immune microenvironment in AE, which could provide potential target signatures for AE diagnosis and immunotherapies.
Article
Full-text available
Echnococcosis is an infection manifesting cyst formation in multiple organs affecting man and animals caused by E. granulosus and E. multilocularis. These cysts may be unilocular (E. granulosus) or multilocular (E. multilocularis). Multilocular cysts have particular importance as their macroscopic appearance is similar to malignant tumors and they carry a poor prognosis. The pathologic findings of 50 echinococcus cases are presented here. Echinococcosis is a serious health problem of rural areas of Turkey, particularly of the central and eastern Anatolia regions. 10381 unilocular and 251 multilocular cyst cases have been found in the Turkish medical literature. Our aim is to establish a discussion on current echinococcosis problem of Turkey. Key words: Echinococcosis, unilocular cyst, multilocular cyst
Article
Full-text available
Both alveolar echinococcosis (AE) and cystic (CE) echinococcosis are prevalent and autochthonous in Austria. Based on historical facts, clinical, histopathological, serological and epidemiological data obtained during the last 15 years, the recent epidemiological situation of both forms of echinococcosis in Austria are described. In total, 38 AE and 519 CE cases have been registered between 1985 and 1999, reflecting an annual incidence of 2.5 and 34.6, respectively. 37 AE (97.4 %) and 222 CE (42.8 %) patients were of Austrian origin, 1 AE patient and 297 (57.2 %) CE patients were of non-Austrian origin. The endemic areas of AE are situated in the western provinces (Vorarlberg, Tyrol), but one focus could also be detected in the north eastern province Lower Austria; most Austrian CE patients are residents of the eastern provinces Burgenland, Lower Austria and Styria.
Article
Full-text available
Human echinococcosis is a zoonotic larval cestode disease usually caused by Echinococcus granulosus or E. multilocularis. Infection is chronic taking years for symptoms to develop. Because diagnosis and treatment are difficult and reservoirs of infection are maintained in domestic livestock, dogs or wildlife, the disease is difficult to assess in terms of public health and requires long-term control interventions. Estimates of numbers of cystic echinococcosis cases that may occur in 2 large endemic zones, North Africa⁄Middle East and China⁄Central Asia, indicates > 423,000 and > 484,000 cases respectively. Globally, 3.6 million DALYs could be lost due to echinoccocosis. Echinococcosis is therefore a neglected disease which is under-reported and requires urgent attention in common with a number of other zoonoses in order to reduce morbidity and to help alleviate poverty in poor pastoral areas of the sub-tropics and temperate zones
Article
Full-text available
Abstract: Echinococcosis is an infection caused by Echinococcus granulosus and E. multilocularis. It manifests as cyst formations in various organs, affecting both humans and animals. The cysts may be unilocular (E. granulosus) or multilocular (E. multilocularis). Multilocular cysts have particular significance, for their macroscopic appearance is reminiscent of malignant tumors and their prognosis is poor. The purpose of this study is to describe our cases and to start a discussion on the current echinococcosis problem in İzmir, western Anatolia. The pathological features of 80 cases of echinococcosis diagnosed at Dokuz Eylül University Pathology Department over the last 21 years have been reviewed. Seventy-two of the 80 cases were caused by E. granulosus and the rest were caused by E. multilocularis. Fifty-five patients (68.75%) were female and 25 (31.25%) were male. The most common localization was the liver (56.25%). Hydatid disease due to cystic echinococcosis is one of the most important public health and economic problems in Turkey. The disease occurs predominantly in eastern Anatolia but may be encountered in any part of the country. Key Words: Echinococcosis, Echinococcus granulosus, E. multilocularis, western Anatolia
Article
Detailed assumptions used in constructing a new indicator of the burden of disease, the disability-adjusted life year (DALY), are presented. Four key social choices in any indicator of the burden of disease are carefully reviewed. First, the advantages and disadvantages of various methods of calculating the duration of life lost due to a death at each age are discussed. DALYs use a standard expected-life lost based on model life-table West Level 26. Second, the value of time lived at different ages is captured in DALYs using an exponential function which reflects the dependence of the young and the elderly on adults. Third, the time lived with a disability is made comparable with the time lost due to premature mortality by defining six classes of disability severity. Assigned to each class is a severity weight between 0 and 1. Finally, a three percent discount rate is used in the calculation of DALYs. The formula for calculating DALYs based on these assumptions is provided.
Article
Detailed assumptions used in constructing a new indicator of the burden of disease, the disability-adjusted life year (DALY), are presented. Four key social choices in any indicator of the burden of disease are carefully reviewed. First, the advantages and disadvantages of various methods of calculating the duration of life lost due to a death at each age are discussed. DALYs use a standard expected-life lost based on model life-table West Level 26. Second, the value of time lived at different ages is captured in DALYs using an exponential function which reflects the dependence of the young and the elderly on adults. Third, the time lived with a disability is made comparable with the time lost due to premature mortality by defining six classes of disability severity. Assigned to each class is a severity weight between 0 and 1. Finally, a three percent discount rate is used in the calculation of DALYs. The formula for calculating DALYs based on these assumptions is provided.