ArticlePDF AvailableLiterature Review

Wildlife as Source of Zoonotic Infections

Authors:

Abstract

Zoonoses with a wildlife reservoir represent a major public health problem, affecting all continents. Hundreds of pathogens and many different transmission modes are involved, and many factors influence the epidemiology of the various zoonoses. The importance and recognition of wildlife as a reservoir of zoonoses are increasing. Cost-effective prevention and control of these zoonoses necessitate an interdisciplinary and holistic approach and international cooperation. Surveillance, laboratory capability, research, training and education, and communication are key elements.
Zoonoses with a wildlife reservoir represent a major
public health problem, affecting all continents. Hundreds of
pathogens and many different transmission modes are
involved, and many factors influence the epidemiology of
the various zoonoses. The importance and recognition of
wildlife as a reservoir of zoonoses are increasing. Cost-
effective prevention and control of these zoonoses neces-
sitate an interdisciplinary and holistic approach and
international cooperation. Surveillance, laboratory capabili-
ty, research, training and education, and communication
are key elements.
T
hroughout history, wildlife has been an important
source of infectious diseases transmissible to humans.
Today, zoonoses with a wildlife reservoir constitute a
major public health problem, affecting all continents. The
importance of such zoonoses is increasingly recognized,
and the need for more attention in this area is being
addressed.
Wildlife is normally defined as free-roaming animals
(mammals, birds, fish, reptiles, and amphibians), whereas
a zoonosis is an infectious disease transmittable between
animals and humans. The total number of zoonoses is
unknown, but according to Taylor et al. (1), who in 2001
catalogued 1,415 known human pathogens, 62% were of
zoonotic origin. With time, more and more human
pathogens are found to be of animal origin. Moreover,
most emerging infectious diseases in humans are
zoonoses. Wild animals seem to be involved in the epi-
demiology of most zoonoses and serve as major reservoirs
for transmission of zoonotic agents to domestic animals
and humans.
Zoonoses with a wildlife reservoir are typically caused
by various bacteria, viruses, and parasites, whereas fungi
are of negligible importance. Regarding prion diseases,
chronic wasting disease occurs among deer in North
America. This prion disease is thus far not known to be
zoonotic. However, hunters and consumers are advised to
take precautions (2,3).
Historical Aspects
Zoonoses have affected human health throughout
times, and wildlife has always played a role. For example,
bubonic plague, a bacterial disease for which rats and fleas
play a central role in transmission, has caused substantial
illness and death around the world since ancient times (4).
A possible epidemic of bubonic plague was described in
the Old Testament, in the First Book of Samuel. The so-
called Black Death emerged in the 14th century and caused
vast losses throughout Asia, Africa, and Europe. The epi-
demic, which originated in the Far East, killed approxi-
mately one third of Europe’s population. However,
bubonic plague still occurs in Asia, Africa, and the
Americas, and the World Health Organization annually
reports 1,000–3,000 cases. In the western United States,
acquisition of plague in humans is linked to companion
animals infested with Yersinia pestis–carrying fleas in
areas of endemic sylvatic disease (5).
Rabies was described in Mesopotamia, in hunting dogs,
as early as 2,300 BC. Recognizable descriptions of rabies
can also be traced back to early Chinese, Egyptian, Greek,
and Roman records (6). In Europe in the medieval age,
rabies occurred in both domestic animals and wildlife.
Rabid foxes, wolves, badgers, and bears have been
described in the literature as well as in figurative art.
Ancient accounts and modern hypotheses suggest that
Alexander the Great, who died in Babylon in 323 BC, died
of encephalitis caused by West Nile virus (7), a virus that
has a wild bird reservoir. Marr and Calisher reported that
as Alexander entered Babylon, a flock of ravens exhibiting
unusual behavior died at his feet (7). In 1999, West Nile
virus was introduced into the United States, where it
caused the ongoing epizootic in birds with a spillover of
infections to humans and equines.
Transmission Modes
Zoonoses with a wildlife reservoir represent a large
spectrum of transmission modes. Several zoonotic agents
can be directly transmitted from wildlife to humans, e.g.,
Francisella tularensis, the causative agent of tularemia,
can be transmitted by skin contact with an infested,
Wildlife as Source of Zoonotic
Infections
Hilde Kruse,* Anne-Mette Kirkemo,* and Kjell Handeland*
Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 10, No. 12, December 2004 2067
*National Veterinary Institute, Oslo, Norway
diseased, or dead hare or rodent. By contrast, rabies virus
is transmitted by bite (saliva) from a rabid animal.
Hantaviruses are spread from rodents to humans by
aerosols in dust from rodent excreta. Zoonotic agents can
also be spread from wildlife to humans indirectly by con-
taminated food and water, for example Salmonella spp.
and Leptospira spp.
Many zoonoses with a wildlife origin are spread
through insect vectors. For example, mosquitoes are well-
known vectors of several wildlife zoonoses, such as Rift
Valley fever, equine encephalitis, and Japanese encephali-
tis. Y. pestis can be spread by fleas, Bacillus anthracis
spores by flies, and Leishmania by sand-flies, whereas
ticks are essential in the spread of Borrelia burgdorferi and
Ehrlichia/Anaplasma.
A good example of a zoonotic agent with many differ-
ent transmission modes is F. tularensis. Rodents and hares
constitute the main sources of infections, and hunters are at
particular risk of acquiring the disease. The transmission
mode also affects the clinical manifestation in humans.
The agent can be transmitted by direct contact through the
handling of an infected carcass and through tick or mos-
quito bites, which cause initial skin symptoms such as
ulcers. Infection may also occur after eating insufficiently
cooked meat from an infected animal or contaminated
drinking water, causing symptoms from the digestive tract,
and by inhalation of contaminated dust, causing a pneumo-
nialike illness.
Salmonella spp. can also be spread from wildlife to
humans in different ways. Reptile-associated salmonel-
losis is a well-described phenomenon, especially among
children. The increasing popularity of keeping reptiles and
other exotic animals as pets presents a public health prob-
lem, as such animals are commonly carriers of Salmonella
and thereby can infect humans directly or indirectly. In
Norway, special types of Salmonella enterica subsp. enter-
ica serovar Typhimurium (S. Typhimurium) occur endem-
ically in hedgehogs and wild passerine birds, causing
sporadic cases and small outbreaks in humans. In 1987, a
nationwide outbreak of S. Typhimurium infections was
traced to chocolate bars that had been contaminated by
wild birds in the factory. In 1999, a waterborne outbreak of
S. Typhimurium infections was linked to a dead seagull
that had contaminated a reservoir water source from which
the water was used untreated (8–10).
B. anthracis, the etiologic agent of anthrax, primarily a
disease of herbivores, can also be transmitted from wildlife
to humans by various modes. The spores formed by the
bacteria are very resistant and have been found to remain
dormant and viable in nature for >100 years (11). Anthrax
is spread by food and water contamination or by the spread
of spores by flies, vultures, and other scavengers. Humans
can be infected by eating meat from infected carcasses or
drinking contaminated water, through the skin by contact
with infected material or by insect bites, and through the
lungs by inhaling spores. Although livestock anthrax is
declining in many parts of the world, the disease remains
enzootic in many national parks, for example, in southern
Africa and North America. Anthrax in wildlife represents a
persistent risk for surrounding livestock and public health
(12).
Factors Influencing the Epidemiology of
Zoonoses with a Wildlife Reservoir
The ecologic changes influencing the epidemiology of
zoonoses with a wildlife reservoir can be of natural or
anthropogenic origin. These include, but are not limited to,
human population expansion and encroachment, reforesta-
tion and other habitat changes, pollution, and climatic
changes.
The spirochete Borrelia burgdorferi, which causes
Lyme borreliosis, has its main reservoir among small
rodents and deer and uses various Ixodes species as vectors
(13). Lyme borreliosis was first recognized in Lyme,
Connecticut, in 1975, and since then, an increasing number
of cases have been reported in North America, Europe, and
Asia. The increasing incidence of Lyme borreliosis in the
northeastern United States in recent years can be explained
by reforestation that has favored transmission of the dis-
ease through increased populations of white-tailed deer
and deer mice and abundance of the tick vector, Ixodes
scapularis.
Wild rodents also constitute a reservoir of hantaviruses
(14). The viruses are shed in urine, droppings, and saliva,
and humans are mainly infected aerogenically by inhaling
aerosols containing the virus. Precipitation, habitat struc-
ture, and food availability are critical environmental fac-
tors that affect rodent population dynamics as well as viral
transmission between animals and subsequently the inci-
dence of human infection. The deer mouse is a reservoir
host for Sin Nombre hantavirus, which causes hantavirus
pulmonary syndrome in the southwestern United States.
Because of climatic changes with increased rainfall in
recent years, host abundance, and thereby spread of the
pathogen, has increased, with subsequent transmission to
humans.
The movement of pathogens, vectors, and animal hosts
is another factor influencing the epidemiology of zoonoses
with a wildlife reservoir. Such movement can, for exam-
ple, occur through human travel and trade, by natural
movement of wild animals including migratory birds, and
by anthropogenic movement of animals. For instance,
infectious agents harbored within insects, animals, or
humans can travel halfway around the globe in <24 hours
in airplanes. Thus, infectious agents can be transported to
the farthest land in less time than it takes most diseases to
PERSPECTIVE
2068 Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 10, No. 12, December 2004
incubate. The appearance of West Nile virus infection in
New York in 1999, and the subsequent spread within the
United States, is an example of introduction and establish-
ment of a pathogen that apparently originated in the
Middle East (15).
Movement of infected wild and domestic animals is an
important factor in the appearance of rabies in new loca-
tions. Rabies virus, which is widely distributed and affects
various animals, especially canids, was introduced into
North America by infected dogs in the early 18th century,
with subsequent spillover to a variety of wild terrestrial
mammals. Rabies became established in raccoons in the
mid-Atlantic states in the late 1970s when raccoons were
translocated from the southeastern United States, where
rabies was endemic in this species (16). Finland experi-
enced an outbreak of rabies linked to raccoon dogs in
1988. The raccoon dog had spread to Finland after this
species was released in western Russia for fur trade.
Rabies most probably arrived in Finland by wolves migrat-
ing from Russia during wintertime along the ice-packed
coast (17). In the Arctic, the ice links the continents togeth-
er. The movement of the arctic fox from the archipelago of
Spitzbergen to Novaja Zemlja in Siberia and from Canada
to Greenland has been described, indicating another way
that rabies can be spread to new areas (18,19).
Bovine tuberculosis caused by Mycobacterium bovis is
another zoonosis in which both natural and anthropogenic
movement of animals has influenced the epidemiology.
This zoonosis is emerging in wildlife in many parts of the
world, and wildlife can represent a source of infection for
domestic animals and humans. Bovine tuberculosis was
probably introduced into Africa with imported cattle dur-
ing the colonial era and thereafter spread to and became
endemic in wildlife (20). In Ireland and Great Britain,
badgers maintain the infection, whereas the brushtail pos-
sum constitutes a main wildlife reservoir in New Zealand.
In parts of Michigan, bovine tuberculosis is endemic
among white-tailed deer, whereas in Europe, both wild
boars and various deer species can be a reservoir of the
pathogen. The natural movement of these reservoir ani-
mals increases the spread of the disease to domestic ani-
mals and thereby its public health impact (21).
The epidemiology of multilocular echinococcosis,
caused by the small tapeworm Echinococcus multilocu-
laris, has also been influenced by the translocation of ani-
mals. The main hosts are canids, especially foxes; the
intermediate hosts are small rodents. Humans can become
accidental intermediate hosts, by ingesting eggs.
Multilocular echinococcosis occurs in large parts of the
Northern Hemisphere. In 1999, E. multilocularis was
detected for the first time in Norway, in the archipelago of
Spitzbergen (10,22). The parasite most probably spread
from Russia, by natural movement of the main host, the
Arctic fox. Establishment of the parasite was possible
because the intermediate host, the sibling vole, had previ-
ously been translocated to Spitzbergen, most likely
through imported animal feed (23). In Copenhagen,
Denmark, in 2000, E. multilocularis was detected in a traf-
fic-killed red fox. The theory is that the fox had traveled by
train from central Europe, where the disease is endemic
(H.C. Wegener, pers. comm.).
During the summer of 2003, an outbreak of monkeypox
occurred in the United States with 37 confirmed human
cases (24). Monkeypox is a rare zoonosis caused by a
poxvirus that typically occurs in Africa. It was first found
in monkeys in 1958 and later on in other animals, especial-
ly rodents. The African squirrel is probably the natural
host. Transmission to humans occurs by contact with
infected animals or body fluids. The cases in the United
States, the first outside Africa, were associated with con-
tact with infected prairie dogs. The outbreak was epidemi-
ologically linked to imported African rodents from Ghana.
Most likely, infected imported rodents have transmitted the
virus to prairie dogs in United States. This transmission
illustrates how non-native animal species can create seri-
ous public health problems when they introduce a disease
to native animal and human populations. Thus, the trans-
portation, sale, or distribution of animals, or the release of
animals into the environment, can represent a risk for
spread of zoonoses.
Microbial changes or adaptation also influence the epi-
demiology of zoonoses with a wildlife reservoir. These
changes include mutations, such as genetic drift in viruses;
activation and silencing of genes; genetic recombinations,
such as genetic shift in viruses; and conjugation, transfor-
mation, and transduction in bacteria. Natural selection and
evolution also play a role. Transmission of adaptive or
genetically changed microorganisms from wildlife to
humans, either directly or indirectly through domestic ani-
mals, may occur in many ways. In this respect an interna-
Wildlife as Source of Zoonotic Infections
Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 10, No. 12, December 2004 2069
Figure 1. Foxes may be a reservoir of zoonotic agents such as
rabies virus and the parasite Echinococcus multilocularis.
tional wildlife trade, often illegal, in which wild animals
end up in live-animal markets, restaurants, and farms, is
important because such practices increase the proximity
between wildlife, domestic animals, and humans (25).
Severe acute respiratory syndrome (SARS) is a current
example of likely microbial adaptation. This viral respira-
tory illness, caused by SARS-associated coronavirus, is
believed to have emerged in Guangdong, China, in
November 2002. SARS was first reported in Asia in
February 2003, and over the next few months, the illness
spread to a global epidemic before it was contained.
According to the World Health Organization, 8,098 cases,
including 774 fatalities, have occurred. The virus has an
unknown reservoir, but wildlife is a likely source of infec-
tion. Natural infection has been demonstrated in palm civet
cats in markets and also in raccoon dogs, rats, and other
animals indigenous to the area where SARS likely origi-
nated (26).
Genetic changes typically influence the epidemiology
of influenza A. Natural infections with influenza A viruses
have been reported in a variety of animal species, includ-
ing birds, humans, pigs, horses, and sea mammals, and its
main reservoir seems to be wild waterfowl, especially
ducks. Influenza A virus has two main surface antigens;
hemagglutinin with 15 subtypes and neuraminidase with 9
subtypes. All these subtypes, in most combinations, have
been isolated from birds, whereas few combinations have
been found in mammals. In the 20th century, the sudden
emergence of antigenically different strains transmissible
in humans, termed antigenic shift, has occurred on four
occasions, each time resulting in a pandemic. “New” pan-
demic strains most certainly emerged after reassortment of
genes of viruses of avian and human origin in a permissive
host (27). The H5N1 strain of a highly pathogenic avian
influenza that caused a severe outbreak in poultry in
Southeast Asia in 2004 (28) demonstrated its capacity to
infect humans; 39 cases, 28 of them fatal, were officially
reported (29). For the human population as a whole, the
main danger appears to be simultaneous infection with an
avian and a human influenza virus. Reassortment could
then occur either in humans or in pigs with the potential
emergence of a virus fully capable of spread among
humans but with antigenic characteristics for which the
human population was immunologically naïve.
Enhanced recognition can also result in an apparent
change in the epidemiology of a zoonosis, for example, the
recognition of an agent that has been present for a long
time but was previously undetected because of lack of
diagnostic tools. Improved methods for molecular charac-
terization have helped describe a larger repertoire of
zoonotic agents.
Recognition and emergence of human tickborne ehrli-
chiosis are recent and continuing events, beginning with
human monocytic ehrlichiosis and human granulocytic
ehrlichiosis, reported first in the United States in 1987 and
1994, respectively. The causative agents, Ehrlichia chaf-
feensis and Anaplasma phagocytophilum, are intracellular
bacteria that are maintained in zoonotic cycles involving
persistently infected deer and rodents (30).
From 1994 to 2004, three zoonotic paramyxoviruses
with a wildlife reservoir have emerged. The Hendra,
Menangle, and Nipah viruses all have a fruit bat reservoir
(31). Humans are infected by close contact with infected
pigs or horses. Hendra virus infection was described in
Australia in 1994, where it caused acute, fatal respiratory
disease in horses and humans. Menangle virus was also
described in Australia, in 1996, where it caused reproduc-
tive disorders in pigs and an influenzalike disease in
humans. Nipah virus was detected in 1998, in Malaysia,
when it caused severe disease with respiratory and neuro-
logic symptoms among pigs and encephalitis with a 40%
death rate in humans in close contact with pigs.
Since 1994, when the isolation of Brucella spp. from
marine mammals was reported for the first time, such
infections have been detected in a wide range of marine
mammal species and populations. The pathologic role of
marine Brucella spp. in animals remains unclear, as does
their zoonotic potential. In 2003, two human cases of com-
munity-acquired granulomatous central nervous system
infections caused by marine Brucella spp. were reported
(32).
Human behavior and demographic factors can also
influence the epidemiology of zoonoses with a wildlife
reservoir. Hiking, camping, and hunting are activities that
may represent risk factors for acquiring certain zoonoses
with a wildlife reservoir, e.g., tickborne zoonoses and
tularemia. Eating habits can also play a role. For example,
eating meat from exotic animals such as bear increases the
risk of acquiring trichinellosis (33). AIDS represents a
PERSPECTIVE
2070 Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 10, No. 12, December 2004
Figure 2. The pathologic role of marine Brucella spp. in animals,
such as pinnipedes, remains unclear, as does their zoonotic
potential.
disease in which demographic factors and human behavior
have contributed to its development into a global public
health problem. The origin of HIV, the virus causing AIDS,
is still a matter of controversy, but HIV likely spread to
humans from nonhuman primates in West Africa (34).
Prevention and Control
Although prevention and control strategies for the var-
ious zoonoses associated with wildlife share many com-
mon aspects, specific strategies are also needed to address
the etiology and epidemiology of the disease, characteris-
tics of the pathogen involved, ecologic factors, and the
population at risk. As wildlife is an essential component in
the epidemiology of many, if not most, zoonoses, wildlife
should be taken into account in the risk analysis frame-
work. Consequently, cost-effective prevention and control
of zoonoses in humans, including risk communication,
necessitate an interdisciplinary and holistic approach that
acknowledges the importance of wildlife as a reservoir.
To increase the capability of recognizing zoonoses with
a wildlife reservoir, better national surveillance systems
for humans and animals are needed, as well as better inter-
national integration and sharing of information from such
systems. Which diseases should be reportable also needs to
be evaluated on a continuous basis. Improved reporting
systems and screening programs for human infections,
including the application of syndromic surveillance, are
warranted to detect new and emerging zoonoses. Efficient
surveillance is dependent upon a laboratory system that is
capable of identifying and characterizing the pathogens in
question. More research is needed to better understand the
epidemiology and pathogenesis of various zoonoses, to
improve diagnostic methods, and to develop cost-effective
vaccines and drugs. Training and education are prerequi-
sites to enable the personnel involved at the various stages,
from field to laboratory personnel, to detect zoonoses, both
new and old.
Information and communication are key components in
any prevention and control strategy. Public education and
behavioral change are also important factors for successful
intervention. Implementing restrictions on anthropogenic
animal movement is another important preventive meas-
ure. For vector-borne zoonoses, vector control should be
an integral part of any intervention strategy.
Interdisciplinary and international collaboration is nec-
essary for the rapid identification and effective manage-
ment of outbreaks of zoonoses. The pivotal role of
international organizations such as World Health
Organization and Office International des Epizooties is
becoming clearer, exemplified by the 2004 avian influenza
outbreak in Southeast Asia. Containing zoonoses with a
wildlife reservoir relies on efficient national, regional, and
international cross-sectional networks that can improve
data sharing and thereby alertness and the timely and
effective response to disease outbreaks.
Dr. Kruse is the head of the Norwegian Zoonoses Centre and
a deputy director at the National Veterinary Institute, Norway.
Her research interests include the epidemiology of zoonotic dis-
eases and antimicrobial resistance.
References
1. Taylor LH, Latham SM, Woolhouse ME. Risk factors for human dis-
ease emergence. Philos Trans R Soc Lond B Biol Sci.
2001;356:983–9.
2. Belay ED, Maddox RA, Williams ES, Miller MW, Gambetti P,
Schonberger LB. Chronic wasting disease and potential transmission
to humans. Emerg Infect Dis. 2004;10:977–84.
3. World Health Organization Consultation on Public Health and
Animal Transmissable Spongiform Encephalopathies: epidemiology,
risk and research requirements. WHO/CDS/CSR/APH/2000.2.
Geneva: The Organization; 1999.
4. Wheelis M. Biological warfare at the 1346 Siege of Caffa. Emerg
Infect Dis. 2002;8:971–5.
5. Perry RD, Fetherston JD. Yersinia pestis–etiologic agent of plague.
Clin Microbiol Rev. 1997;10:35–66.
6. Blancou J. History of the surveillance and control of transmissible
animal diseases. Paris: Office International des Epizooties; 2003.
7. Marr JS, Calisher CH. Alexander the Great and West Nile virus
encephalitis. Emerg Infect Dis. 2003;9:1599–603.
8. Refsum T, Handeland K, Baggesen DL, Holstad G, Kapperud G.
Salmonellae in avian wildlife in Norway from 1969 to 2000. Appl
Environ Microbiol. 2002;68:5595–9.
9. Handeland K, Refsum T, Johansen BS, Holstad G, Knutsen G,
Solberg I, et al. Prevalence of Salmonella Typhimurium infection in
Norwegian hedgehog populations associated with two human disease
outbreaks. Epidemiol Infect. 2002;128:523–7.
10. Hofshagen M, Aavitsland P, Kruse H. Trends and sources of zoonot-
ic agents in animals, feedingstuffs, food, and man in Norway, 2003.
Report to the EU. Oslo: Norwegian Department of Agriculture; 2004.
11. Redmond C, Pearce MJ, Manchee RJ, Berdal BP. Deadly relic of the
Great War. Nature. 1998;393:747–8.
12. Hugh-Jones ME, de Vos V. Anthrax and wildlife. Rev Sci Tech.
2002;21:359–83.
13. Barbour AG, Fish D. The biological and social phenomenon of Lyme
disease. Science. 1993;260:1610–6.
14. Schmaljohn C, Hjelle B. Hantaviruses: a global disease problem.
Emerg Infect Dis. 1997;3:95–104.
15. Rappole JH, Derrickson SR, Hubálek Z. Migratory birds and spread
of West Nile virus in the Western Hemisphere. Emerg Infect Dis.
2000;6:319–28.
16. Smith JS, Sumner JW, Roumillat LF, Baer GM, Winkler WG.
Antigenic characteristics of isolates associated with a new epizootic
of raccoon rabies in the U.S. J Infect Dis. 1984;149:769–74.
17. Sihvonen L. Documenting freedom from rabies and minimising the
risk of rabies being re-introduced to Finland. Rabies Bulletin Europe.
2003;27(2):5–6.
18. Prestrud P, Krogsrud J, Gjertz I. The occurrence of rabies in the
Svalbard islands of Norway. J Wildl Dis. 1992;28:57–63.
19. Ballard WB, Follmann EH, Ritter DG, Robards MD, Cronin MA.
Rabies and canine distemper in an arctic fox population in Alaska. J
Wildl Dis. 2001;37:133–7.
20. Cosivi O, Meslin FX, Daborn CJ, Grange JM. Epidemiology of
Mycobacterium bovis infection in animals and humans, with particu-
lar reference to Africa. Rev Sci Tech. 1995;14:733–46.
Wildlife as Source of Zoonotic Infections
Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 10, No. 12, December 2004 2071
21. de Lisle GW, Bengis RG, Schmitt SM, O’Brian DJ. Tuberculosis in
free-ranging wildlife: detection, diagnosis and management. Rev Sci
Tech. 2002;21:317–34.
22. Henttonen H, Fuglei E, Gower CN, Haukisalmi V, Ims RA,
Niemimaa J, et al. Echinococcus multilocularis on Svalbard: intro-
duction of an intermediate host has enabled the local life-cycle.
Parasitology. 2001;123:547–52.
23. Fredga K, Jaarola M, Ims RA, Steen H, Yoccoz N. The “common
vole” in Svalbard identified as Microtus epiroticus by chromosome
analysis. Polar Research. 1990;8:283–90.
24. Reed KD, Melski JW, Graham MB, Regnery RL, Sotir MJ, Wegner
MV, et al. The detection of monkeypox in humans in the western
hemisphere. N Engl J Med. 2004;350:342–50.
25. Bell D, Roberton S, Hunter PR. Animal origins of the SARS coron-
avirus: possible links with the international trade in small carnivores.
Philos Trans R Soc Lond B Biol Sci. 2004;359:1107–14.
26. Guan Y, Zheng BJ, He YQ, Liu XL, Zhuang ZX, Cheung CL, et al.
Isolation and characterization of viruses related to the SARS coron-
avirus from animals in southern China. Science. 2003;302:276–8.
27. Webster RG, Bean WJ, Gorman OT, Chambers TM, Kawaoka Y.
Evolution and ecology of influenza A viruses. Microbiol Rev.
1992;56:152–79.
28. Li KS, Guan Y, Wang J, Smith GJD, Xu KM, Duan L, et al. Genesis
of a highly pathogenic and potentially pandemic H5N1 influenza
virus in eastern Asia. Nature. 2004;430:209–13.
29. World Health Organization [homepage on the Internet].
Communicable disease surveillance & response. Confirmed human
cases of avian influenza A(H5N1). 7 Sept [cited 13 Sept 2004].
Available from http://www.who.int/csr/disease/avian_influenza/
country/cases_table_2004_09_07/en/
30. Dumler JS, Walker DH. Tick-borne ehrlichioses. Lancet Infect Dis.
2001;0(1):21–8. Available from http://infectionpdf.thelancet.com/
pdfdownload?uid=laid.0.1.review_and_opinion.17182.1&x=x.pdf
31. Brown C. Virchow revisited: emerging zoonoses. ASM News.
2003;69:493–7.
32. Sohn AH, Probert WS, Glaser CA, Gupta N, Bollen AW, Wong JD, et
al. Human neurobrucellosis with intracerebral granuloma caused by a
marine mammal Brucella spp. Emerg Infect Dis. 2003;9:485–8.
33. Schellenberg RS, Tan BJK, Irvine JD, Stockdale DR, Gajadhar AA,
Serhir B, et al. An outbreak of trichinellosis due to consumption of
bear meat infected with Trichinella nativa, in 2 northern
Saskatchewan communities. J Infect Dis. 2003;188:835–43.
34. Feng G, Bailes E, Robertson DL, Chen Y, Rodenburg CM, Michael
SF, et al. Origin of HIV-1 in the chimpanzee Pan troglodytes
troglodytes. Nature. 1999;397:436–41.
Address for correspondence: Hilde Kruse, Norwegian Zoonosis Centre,
National Veterinary Institute, POB 8156 Dep., 0033 Oslo, Norway; fax:
+47 23 21 64 85; email: hilde.kruse@vetinst.no
PERSPECTIVE
2072 Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 10, No. 12, December 2004
www.cdc.gov/ncidod/EID/cover_images/covers.htm
... Zoonotic diseases have caused a series of major global public health issues (malaria, yellow fever, avian flu, swine flu, West Nile virus, MERS, SARS, etc.), culminating in the current coronavirus health crisis (Altaf, 2016;Altaf, 2020). Different pathogens have different modes of transmission (Kruse et al., 2004;Van Vliet et al., 2017), so the risk of zoonotic diseases depends on the type of animals with which humans are in contact (as well as the duration and nature of contact) (Bilal et al., 2021). For example, the prevalence of diseases from fish to humans is very low (EHS, 2016b), while the risk of transmission from amphibians is higher due to human sensitivity to their porous skin (EHS, 2016a). ...
Article
Full-text available
Background: The use of animals and animal-derived products in ethnopharmacological applications is an ancient human practice that continues in many regions today. The local people of the Himalayan region harbor rich traditional knowledge used to treat a variety of human ailments. The present study was intended with the aim of examining animal-based traditional medicine utilized by the population of the Himalayan region of Azad Jammu and Kashmir. Methods: Data were collected from 2017 to 2019 through individual and group interviews. Data on traditional uses of animal products were analyzed, utilizing following indices such as the frequency of citation, use value, relative importance, similarity index, principal component analysis, and cluster analysis to find the highly preferred species in the area. Results: Ethnomedicinal uses of 62 species of vertebrates and invertebrates were documented. Flesh, fat, bone, whole body, milk, skin, egg, head, feathers, bile, blood, and honey were all used in these applications. The uses of 25 animals are reported here for the first time from the study area (mainly insects and birds, including iconic species like the kalij pheasant, Lophura leucomelanos ; Himalayan monal, L. impejanus ; and western tragopon, Tragopan melanocephalus ). The diversity and range of animal-based medicines utilized in these communities are indications of their strong connections with local ecosystems. Conclusion: Our results provide baseline data valuable for the conservation of vertebrate and invertebrate diversity in the region of Himalayan of Azad Jammu and Kashmir. It is possible that screening this fauna for medicinally active chemicals could contribute to the development of new animal-based drugs.
... Zoonotic diseases have the potential to cause global pandemics. Large-scale zoonosis outbreaks, which resulted in large numbers of deaths, have wreaked havoc on economies, political order, and societies throughout history [31]. ...
Article
Full-text available
The world and the way things are done have changed, from selling clothing in brick-and-mortar stores to online shopping through social media platforms. Population growth has significantly contributed to an increased clothing demand, which, in turn, has increased the demand for animal skin. Traditional markets, also known as wet markets, are considered as major zoonotic disease reservoirs due to human and animal contact. Some groups and individuals continue to believe in traditional medicine and clothing that is made from animal skin, and such beliefs are more accessible with the presence of wet markets. Hence, animal poaching and trafficking have increased to meet the high demands, primarily in the Western world. Poverty is a well-known motivation to commit a crime. Conservationists should not only look at the animal regulation site to propose a solution to animal poaching and trafficking but should also consider communal poverty. Thus, this review aimed to highlight the role of wet market and animal skin fashion on animal welfare and human health.
... The primary source of zoonotic virus from farm and wild animal causes disease in human. Approximately 60 to 75% of known human pathogens ascend from animals [5]. Animal reservoirs have been involved in numerous virus families such as Filoviridae, Arenaviridae, Flaviviridae, and Bunyaviridae that were responsible to transmitted virus animals to humans vice versa. ...
Chapter
Infectious diseases are initiated by small pathogenic living germs that are transferred from person to person by direct or indirect contact. Recently, different newly emerging and reemerging infectious viral diseases have become greater threats to human health and global stability. Investigators can anticipate epidemics through the advent of numerous mathematical tools that can predict specific pathogens and identify potential targets for vaccine and drug design and will help to fight against these challenges. Currently, computational approaches that include mathematical and essential tools have unfolded the way for a better understanding of newly originated emerging and re-emerging infectious disease, pathogenesis, diagnosis, and treatment option of specific diseases more easily, where immunoinformatics plays a crucial role in the discovery of novel peptides and vaccine candidates against the different viruses within a short time. Computational approaches include immunoinformatics, and computer-aided drug design (CADD)-based model trained biomolecules that offered reasonable and quick implementation approaches for the modern discovery of effective viral therapies. The essence of this review is to give insight into the multiple approaches not only for the detection of infectious diseases but also profound how people can pick appropriate models for the detection of viral therapeutics through computational approaches.
... Due to the fact that world is being confronted with a recurrent epidemics and other public health issues, this approach improves our understanding of health and diseases as well as prediction, detection, prevention, and control of infections and other issues affecting health and well-being in the human-animal-ecosystem interface, which will lead to sustainable development goals, and ultimately to equity in the world. It is believed that any plan designed for zoonotic diseases should blle based on this approach [8][9][10]. Providing new solutions and tools for effective research and services to support the development of norms, regulations, and policies for the benefit of humanity, animals, and the environment is crucial for our present and future generations [11]. ...
Article
Zoonotic diseases are seen as a major public health concern. Routes of the rapid transmission of zoonotic diseases and the economic damage they cause to communities are all reasons why health institutions and systems need to pay more attention to these diseases. Strategic planning is one of the important tasks of policymakers in every organization and system. It is a very reliable and useful tool for leading all kinds of organizations, including health organizations. Countries with clear policy plans have succeeded in controlling and reducing zoonotic diseases. Such countries used appropriate strategic planning and pursued annual goals to control and prevent diseases. Three important steps (strategy development, strategy implementation and strategy evaluation) should be considered in developing a strategic planning for controlling and prevention of zoonotic diseases. Health systems need to develop strategic planning in order to upgrade their capabilities in combating zoonotic diseases. These programs must be flexible, in line with the one health approach, based on the current needs, and aligned with the new challenges faced with health systems. The strategic planning is directly related to national and international policies, organizational goals and missions, dynamism, degree of complexity, and organizational structure of each country's health system.
... Like elsewhere, different viruses including those that cause high mortalities and morbidities are circulating in animal populations in the Caribbean region. Furthermore, wildlife come in proximity to companion animals, livestock and humans in some of the islands, creating an ideal environment for interspecies transmission events (Alfonso et al., 2020;Gainor et al., 2021b;Kruse et al., 2004;Seetahal et al., 2019). This review provides for the first time an updated and comprehensive compilation of previously published reports on different viral infections in companion animals, livestock and wildlife from the Caribbean islands within the Greater and Lesser Antilles. ...
Article
Full-text available
Viruses pose a major threat to animal health worldwide, causing significant mortalities and morbidities in livestock, companion animals and wildlife, with adverse implications on human health, livelihoods, food safety and security, regional/national economies, and biodiversity. The Greater and Lesser Antilles consist of a cluster of islands between the North and South Americas and is habitat to a wide variety of animal species. This review is the first to put together decades of information on different viruses circulating in companion animals, livestock, and wildlife from the Caribbean islands of Greater and Lesser Antilles. Although animal viral diseases have been documented in the Caribbean region since the 1940s, we found that studies on different animal viruses are limited, inconsistent, and scattered. Furthermore, a significant number of the reports were based on serological assays, yielding preliminary data. The available information was assessed to identify knowledge gaps and limitations, and accordingly, recommendations were made, with the overall goal to improve animal health and production, and combat zoonoses in the region. This article is protected by copyright. All rights reserved
... Our behavioral questionnaire, designed to gain insight into overall patterns around animal contact, indicated that contacts with animals occurred most frequently through handling and raising animals particularly poultry, swine and cattle, having animals come in the dwelling and slaughtering animals. This raises concern, since these animals that the participants had regular contact with carry several diseases-such as avian influenza, SARS [69], hantavirus, and rabies-that can be transmitted to humans and have epidemic or pandemic potential [70,71]. Human infections of highly pathogenic avian influenza from poultry have been first reported in Thailand where poultry farming has been propagating in the last few decades [72]. ...
Article
Full-text available
Background Interactions between humans and animals are the key elements of zoonotic spillover leading to zoonotic disease emergence. Research to understand the high-risk behaviors associated with disease transmission at the human-animal interface is limited, and few consider regional and local contexts. Objective This study employed an integrated behavioral–biological surveillance approach for the early detection of novel and known zoonotic viruses in potentially high-risk populations, in an effort to identify risk factors for spillover and to determine potential foci for risk-mitigation measures. Method Participants were enrolled at two community-based sites (n = 472) in eastern and western Thailand and two hospital (clinical) sites (n = 206) in northeastern and central Thailand. A behavioral questionnaire was administered to understand participants’ demographics, living conditions, health history, and animal-contact behaviors and attitudes. Biological specimens were tested for coronaviruses, filoviruses, flaviviruses, influenza viruses, and paramyxoviruses using pan (consensus) RNA Virus assays. Results Overall 61/678 (9%) of participants tested positive for the viral families screened which included influenza viruses (75%), paramyxoviruses (15%), human coronaviruses (3%), flaviviruses (3%), and enteroviruses (3%). The most salient predictors of reporting unusual symptoms (i.e., any illness or sickness that is not known or recognized in the community or diagnosed by medical providers) in the past year were having other household members who had unusual symptoms and being scratched or bitten by animals in the same year. Many participants reported raising and handling poultry (10.3% and 24.2%), swine (2%, 14.6%), and cattle (4.9%, 7.8%) and several participants also reported eating raw or undercooked meat of these animals (2.2%, 5.5%, 10.3% respectively). Twenty four participants (3.5%) reported handling bats or having bats in the house roof. Gender, age, and livelihood activities were shown to be significantly associated with participants’ interactions with animals. Participants’ knowledge of risks influenced their health-seeking behavior. Conclusion The results suggest that there is a high level of interaction between humans, livestock, and wild animals in communities at sites we investigated in Thailand. This study highlights important differences among demographic and occupational risk factors as they relate to animal contact and zoonotic disease risk, which can be used by policymakers and local public health programs to build more effective surveillance strategies and behavior-focused interventions.
... Wild canids are involved in the maintenance and spread of major zoonoses of infectious and parasitic etiology, including rabies, echinococcosis/hydatidosis by Echinococcus granulosus, alveolar echinococcosis by Echinococcus multilocularis, and trichinellosis [57,58]. In the particular case of sylvatic rabies in Europe, the dispersal of young foxes (Vulpes vulpes) was shown to be a key determinant of the wavefront advancement speed, in the range of 20 to 60 km/year, with maxima of 100 km/year [59,60]. ...
Article
Full-text available
Wildlife dispersal directly influences population expansion patterns, and may have indirect effects on the spread of wildlife diseases. Despite its importance to conservation, little is known about dispersal for several species. Dispersal processes in expanding wolf (Canis lupus) populations in Europe is not well documented. Documenting the natural dispersal pattern of the expanding wolf population in the Alps might help understanding the overall population dynamics and identifying diseases that might be connected with the process. We documented 55 natural dispersal events of the expanding Italian wolf alpine population over a 20-year period through the use of non-invasive genetic sampling. We examined a 16-locus microsatellite DNA dataset of 2857 wolf samples mainly collected in the Western Alps. From this, we identified 915 individuals, recaptured 387 (42.3%) of individuals, documenting 55 dispersal events. On average, the minimum straight dispersal distance was 65.8 km (±67.7 km), from 7.7 km to 517.2 km. We discussed the potential implications for maintaining genetic diversity of the population and for wildlife diseases spreading.
... The One Health concept recognizes that human health is closely linked to animal and environmental health. Zoonotic diseases with a wildlife reservoir are usually caused by various bacteria, viruses, and parasites, while fungi are of secondary importance [19]. Studies indicate that, fortunately, none of the diseases found in chamois pose a significant health risk to humans or other wildlife species. ...
Article
Full-text available
In this paper, we provide an overview of the causes of death of Alpine chamois (Rupicapra r. rupicapra) diagnosed in the national passive health surveillance of chamois in Slovenia. From 2000 to 2020, 284 free-ranging chamois provided by hunters were necropsied at the Veterinary Faculty, University of Ljubljana, Slovenia. Depending on the results of complete necropsy, histopathological, bacteriological, parasitological, and virological examinations, a descriptive data analysis was performed. The most common causes of death in chamois were infectious diseases (82.2%), followed by non-infectious diseases (11.8%). Of all the causes of death, parasitic infections accounted for 70.3%, trauma for 9.7%, and bacterial infections for 9.3% of all cases. Less common diseases were viral infections, neoplasms, winter starvation, and metabolic disorders.
Thesis
In the last decades, the emergence of ticks and tick-borne diseases (TBD) has become a public health concern in Europe. In Piedmont region (Northwestern Italy) ticks were rare in the past, especially in mountain areas. However, in the recent years, we have been observing an increase in tick abundance in the environment but also in reported tick-bites and TBD cases in humans. Tick-borne diseases are characterized by complex transmission cycles; thus, an integrated approach is needed. The ‘One Health’ (OH) approach may effectively provide scientific evidence for TBD surveillance and prevention, and support decision makers. This PhD project investigates the presence and abundance of tick vectors and tick-borne pathogens in two natural areas of Piedmont region, recently invaded by ticks, to identify potential risk factors involved in their emergence, and to evaluate their impact on public health. Additionally, we aimed to identify ideal surveillance and control elements based on a OH approach. We recorded a further expansion of Ixodes ricinus in Europe, being maintained at altitudes up to around 1700 m a.s.l. The abundance of I. ricinus was significantly associated with altitude, habitat type and signs of roe deer presence and molecular analyses demonstrated its infection with several zoonotic agents: B. burgdorferi sensu lato, spotted fever group rickettsiae, Anaplasma phagocytophilum, Borrelia miyamotoi and Neoehrlichia mikurensis. Dermacentor spp. ticks were also collected, in particular D. marginatus and D. reticulatus. Rickettsia slovaca and Candidatus Rickettsia rioja, causative agents of SENLAT (Scalp Eschar Neck Lymphadenopathy) syndrome in humans, infected Dermacentor ticks and wild boar tissues, suggesting the greater contribution of wild boar in its eco-epidemiology and dispersion in the study area. We also confirmed that Piedmontese population is exposed to infected tick bites. However, a generalized low awareness was observed among the population; in fact, although most citizens perceive ticks as a health threat, they do not frequently adopt protective measures. This justified the longer duration of tick attachment generally observed in bitten patients (> 24 hours). A serosurvey in wild ungulates was additionally carried out in mountain areas to assess the circulation of tick-borne encephalitis virus. No serum sample yielded positive results, indicating the absence of this pathogen in our territory so far. Notwithstanding, this activity should be maintained in the long term for early pathogen detection and rapid response, since the virus is circulating in bordering areas of the Piedmont. Regarding tick ecology, this project integrated some investigations about tick symbionts, whose presence is key for tick development and survival. We detected the infection of Francisella-like endosymbionts in Dermacentor spp. which have been previously associated with positive effects in the tick fitness, by providing nutrimental support to ticks. Moreover, a large-scale study was carried out to investigate the infection of Rickettsiella symbionts in I. ricinus populations in Europe, identifying a great diversity within the Rickettsiella genus. Research on TBD requires the knowledge and skills from different disciplines. However, transdisciplinarity seems to work when structural support is provided by the system; instead, critical elements such as insufficient funding, system decentralization and monodisciplinary approaches threaten the response capacity of the systems. One Health operation and infrastructure aspects can strengthen surveillance systems and could be particularly important in areas of recent spread of ticks and TBD.
Article
Full-text available
A highly pathogenic avian influenza virus, H5N1, caused disease outbreaks in poultry in China and seven other east Asian countries between late 2003 and early 2004; the same virus was fatal to humans in Thailand and Vietnam. Here we demonstrate a series of genetic reassortment events traceable to the precursor of the H5N1 viruses that caused the initial human outbreak in Hong Kong in 1997 (refs 2-4) and subsequent avian outbreaks in 2001 and 2002 (refs 5, 6). These events gave rise to a dominant H5N1 genotype (Z) in chickens and ducks that was responsible for the regional outbreak in 2003-04. Our findings indicate that domestic ducks in southern China had a central role in the generation and maintenance of this virus, and that wild birds may have contributed to the increasingly wide spread of the virus in Asia. Our results suggest that H5N1 viruses with pandemic potential have become endemic in the region and are not easily eradicable. These developments pose a threat to public and veterinary health in the region and potentially the world, and suggest that long-term control measures are required.
Article
Full-text available
The chromosomes were studied in six individuals from a population of Microtus from Grumantbyen, Svalbard, and in six Microtur arualis (Pallas 1778) from Lauwersee, Holland. It was shown that the voles from Svalbard did not belong, as earlier supposed, to the species M. arualis (2n = 46) but to M . epiroticus (Ondrias, 1966) (2n = 54). We suggest that the Svalbard voles were introduced by man between 1920 and 1960 together with hay on Russian ships from the vicinity of Leningrad, USSR.
Article
Full-text available
In this review we examine the hypothesis that aquatic birds are the primordial source of all influenza viruses in other species and study the ecological features that permit the perpetuation of influenza viruses in aquatic avian species. Phylogenetic analysis of the nucleotide sequence of influenza A virus RNA segments coding for the spike proteins (HA, NA, and M2) and the internal proteins (PB2, PB1, PA, NP, M, and NS) from a wide range of hosts, geographical regions, and influenza A virus subtypes support the following conclusions. (i) Two partly overlapping reservoirs of influenza A viruses exist in migrating waterfowl and shorebirds throughout the world. These species harbor influenza viruses of all the known HA and NA subtypes. (ii) Influenza viruses have evolved into a number of host-specific lineages that are exemplified by the NP gene and include equine Prague/56, recent equine strains, classical swine and human strains, H13 gull strains, and all other avian strains. Other genes show similar patterns, but with extensive evidence of genetic reassortment. Geographical as well as host-specific lineages are evident. (iii) All of the influenza A viruses of mammalian sources originated from the avian gene pool, and it is possible that influenza B viruses also arose from the same source. (iv) The different virus lineages are predominantly host specific, but there are periodic exchanges of influenza virus genes or whole viruses between species, giving rise to pandemics of disease in humans, lower animals, and birds. (v) The influenza viruses currently circulating in humans and pigs in North America originated by transmission of all genes from the avian reservoir prior to the 1918 Spanish influenza pandemic; some of the genes have subsequently been replaced by others from the influenza gene pool in birds. (vi) The influenza virus gene pool in aquatic birds of the world is probably perpetuated by low-level transmission within that species throughout the year. (vii) There is evidence that most new human pandemic strains and variants have originated in southern China. (viii) There is speculation that pigs may serve as the intermediate host in genetic exchange between influenza viruses in avian and humans, but experimental evidence is lacking. (ix) Once the ecological properties of influenza viruses are understood, it may be possible to interdict the introduction of new influenza viruses into humans.
Article
Virchow's still-relevant call to consider "one medicine" demands an interdisciplinary understanding of diseases and microbial ecology.
Article
Tick-transmitted ehrlichiae are small obligately intracellular bacteria that are maintained in zoonotic cycles involving persistently ehrlichaemic rodents, ruminants, or canids. Ehrlichiae grow as clusters within a cytoplastic vacuole in monocytes, macrophages, and neutrophils, and in animal ehrlichioses also in platelets, erythrocytes, and endothelial cells. Ongoing reclassification of ehrlichiae will place the agent of human granulocytic ehrlichiosis (HGE), Ehrlichia phagocytophila, in the genus Anaplasma, whereas E chaffeensis, the agent of human monocytotropic ehrlichiosis (HME), and E ewingii, which also grows in neutrophils, remain in the genus Ehrlichia. HGE is transmitted by Ixodes species ticks in the upper midwestern and northeastern USA, northern California, and northwestern and eastern Europe. Ranging in severity from mild or symptomless to fatal (0·7%), HGE presents nonspecifically except for frequent thrombocytopenia, leucopenia, and elevated hepatic transaminases. HME presents similarly in the southwestern and south-central USA, but more often manifests as meningoencephalitis, adult respiratory distress syndrome, acute renal failure, rash, and death (2·7%). Diagnosis of human ehrlichioses is usually achieved by a four-fold rise in antibody immunofluorescence titre or by species-specific PCR. Detection of ehrlichiae in leucocytes in peripheral blood smears is achieved more often in HGE than HME. Doxycycline is the drug of choice for human ehrlichioses in most clinical situations. Higher recognised incidences, additional clinical manifestations, wider worldwide geographic distribution, and further discoveries of new human ehrlichioses are likely.
Article
After the first recorded outbreak of rabies in the Svalbard Islands (Norway) in 1980, brain tissue from 817 trapped arctic foxes (Alopex lagopus) was tested for rabies by a direct fluorescent antibody test. During the same period (1980 to 1990), 29 arctic foxes, 23 polar bears (Ursus maritimus), 19 reindeer (Rangifer tarandus) and five ringed seals (Phoca hispida) were also tested using the same technique. These animals had either been found dead, killed because of abnormal behavior or were apparently healthy when they were collected. Rabies virus antigen was not detected in any of the trapped foxes. Rabies was confirmed in two foxes in 1981, two foxes and one reindeer in 1987, and in one fox in 1990. The presence of rabies in the Svalbard archipelago probably resulted from immigration over the sea ice of an infected host.
Article
A panel of 23 monoclonal antibodies to the nucleocapsid protein of rabies virus was used to study the antigenic character of isolates of rabies virus from raccoons in the mid-Atlantic region of the United States. Comparison of the reaction pattern of these isolates with that of isolates of rabies virus collected from areas of major rabies outbreaks (skunk rabies in the midwestern United States, fox rabies in the northeastern United States, and raccoon rabies in the southeastern United States) suggests that this new epizootic originated with the transportation of rabid raccoons from the southeastern United States.
Article
Lyme disease, unknown in the United States two decades ago, is now the most common arthropod-borne disease in the country and has caused considerable morbidity in several suburban and rural areas. The emergence of this disease is in part the consequence of the reforestation of the northeastern United States and the rise in deer populations. Unfortunately, an accurate estimation of its importance to human and animal health has not been made because of difficulties in diagnosis and inadequate surveillance activities. Strategies for prevention of Lyme disease include vector control and vaccines.