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Risk factors for human brucellosis among a pastoralist community in South-West Kenya, 2015

  • Zoonotic Disease Unit
  • Washington State University, Global Health Program -- Kenya


Abstract Objective Brucellosis is one of the top five priority zoonosis in Kenya because of the socio-economic burden of the disease, especially among traditional, livestock keeping communities. We conducted a 1 year, hospital based, unmatched case–control study to determine risk factors for brucellosis among Maasai pastoralists of Kajiado County in 2016. A case was defined by a clinical criteria; fever or history of fever and two clinical signs suggestive of brucellosis and a positive competitive enzyme-linked immunosorbent assay test (c-ELISA). A control was defined as patients visiting the study facility with negative c-ELISA. Unconditional logistic regression was used to study association between exposure variables and brucellosis using odds ratios (OR) and 95% confidence intervals (CI). Results Forty-three cases and 86 controls were recruited from a population of 4792 individuals in 801 households. The mean age for the cases was 48.7 years while that of the controls was 37.6 years. The dominant gender for both cases (62.7%) and controls (58.1%) groups was female. Regular consumption of un-boiled raw milk and assisting animals in delivery were significantly associated with brucellosis by OR 7.7 (95% CI 1.5–40.1) and OR 3.7 (95% CI 1.1–13.5), respectively.
Muturietal. BMC Res Notes (2018) 11:865
Risk factors forhuman brucellosis
amongapastoralist community inSouth-West
Kenya, 2015
Mathew Muturi1* , Austine Bitek2, Athman Mwatondo1, Eric Osoro3, Doris Marwanga4, Zeinab Gura5,
Phillip Ngere6, Zipporah Nganga7, S. M. Thumbi3,5 and Kariuki Njenga3
Objective: Brucellosis is one of the top five priority zoonosis in Kenya because of the socio-economic burden of
the disease, especially among traditional, livestock keeping communities. We conducted a 1 year, hospital based,
unmatched case–control study to determine risk factors for brucellosis among Maasai pastoralists of Kajiado County
in 2016. A case was defined by a clinical criteria; fever or history of fever and two clinical signs suggestive of brucellosis
and a positive competitive enzyme-linked immunosorbent assay test (c-ELISA). A control was defined as patients visit-
ing the study facility with negative c-ELISA. Unconditional logistic regression was used to study association between
exposure variables and brucellosis using odds ratios (OR) and 95% confidence intervals (CI).
Results: Forty-three cases and 86 controls were recruited from a population of 4792 individuals in 801 households.
The mean age for the cases was 48.7 years while that of the controls was 37.6 years. The dominant gender for both
cases (62.7%) and controls (58.1%) groups was female. Regular consumption of un-boiled raw milk and assisting ani-
mals in delivery were significantly associated with brucellosis by OR 7.7 (95% CI 1.5–40.1) and OR 3.7 (95% CI 1.1–13.5),
Keywords: Brucellosis, Risk factors, Kenya
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Brucellosis is a debilitating febrile illness in humans and
reproductive disease of livestock, caused by bacteria
of the genus Brucella [1]. ere are six Brucella species
based on primary host preference, but only four have
zoonotic potential; B. melitensis (goats and sheep), Bru-
cella abortus (cattle), B. suis (swine) and B. canis (dogs)
[25]. Human infection occurs through direct contact
with infected animal tissues like products of abortion
and blood or ingestion of unpasteurized milk and dairy
products [2, 6]. Although livestock are the primary
source of human infection, wild animals may act as res-
ervoirs in regions with human-wildlife interaction [7,
8]. Human brucellosis presents as an acute to chronic
illness characterized by fever and other constitutional
symptoms such as joint pains, fatigue and muscle ache
that vary with the stage of infection and body system
affected [9, 10]. e disease has a low mortality rate, but
the relapsing and chronic nature of human infection, the
long cause of treatment and negative implication on live-
stock trade qualifies brucellosis as a serious public health
and socio-economic problem [2, 9, 1115].
Brucellosis is the most common zoonotic infection
globally with more than half a million human cases annu-
ally, however, infection rates vary significantly between
developed and developing countries [1, 16, 17]. e
human disease has been eliminated in most developed
countries like Canada, Japan and Australia but remains
endemic in most developing countries in Asia, the Mid-
dle East, Eastern Europe, Latin America and Africa [1,
16, 1820].
In Kenya, brucellosis is ranked as a top priority zoon-
osis due to the socio-economic burden and amenability
Open Access
BMC Research Notes
1 Kenya Zoonotic Disease Unit–Ministry of Agriculture, Livestock
and Fisheries and Ministry of Health, P.O. Box 20811-00202, Nairobi, Kenya
Full list of author information is available at the end of the article
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Muturietal. BMC Res Notes (2018) 11:865
to control, however, as is common with other neglected
zoonotic diseases, establishing the true morbidity and
socio-economic impact of the disease is a challenge
because of misdiagnosis and underreporting [21]. Stud-
ies in Kenya indicate high prevalence in humans and
livestock although this varies with geographical region
and livestock production system [2227]. Brucellosis is
endemic in Kenya and identifying potential risk factors
of brucellosis among the most vulnerable populations;
primarily rural livestock keeping communities is impor-
tant in defining control and prevention strategies. We
conducted a case–control study in a pastoral community
in rural Kenya to identify potential risk factors for bru-
cellosis as a step towards comprehensive understanding
of the disease among pastoralists to inform public health
Main text
Materials andmethods
Study area andpopulation
e study was conducted in Arroi, Sultan-Hamud and
Mashuru sub-counties in Kajiado East sub-county, Kenya
(Fig. 1). e study area is an arid rangeland inhabited
primarily by the Maasai nomadic pastoralist community
[23, 28]. e site was selected because a previous study
had reported high brucellosis prevalence and because it
represent an ecosystem with high frequency of human-
livestock-wildlife interaction [23, 29, 30].
Study design
We conducted a hospital based unmatched case–con-
trol study in three health facilities that historically had
the highest patient load in the year preceding the study.
Participants were recruited from 80 randomly selected
households in the study area that were part of an ongoing
longitudinal brucellosis study in humans and livestock
(population = 4792 people). To enhance case finding at
health facilities, recruited household members were sen-
sitized on brucellosis using a community level case defi-
nition adapted from the World Health Organisation, and
provided with free treatment at the participating health
facility [2]. e community case definition for brucellosis
used was fever of undetermined origin with at least one
of the following symptoms; chills, lethargy, joint pains,
body ache, abdominal pain and headaches.
Fig. 1 Map of Kenya showing Kajiado County in red and the study site in grey
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Muturietal. BMC Res Notes (2018) 11:865
Sample size calculation
Sample size was calculated using the Kelsey Kelsey for-
mula for unmatched case control studies using an open-
Epi version 2 open source online calculator (http://www.
opene [31]. e appropriate sample size was
determined using a power of 0.8 and significance level of
0.05 to detect an odds ratio greater than 3 for exposure
factors present in 20% of controls as estimated in other
similar studies [3, 32]. A control to case ratio of 2:1 was
used to improve study power. is yielded a sample size
of 43 cases and 86 controls.
Selection ofcases andcontrols
A case was defined as any person from the study popula-
tion presenting to any of the three health facilities with
fever or history of fever (> 37.5 °C) and at-least two of
the following signs; joint pains, joint swelling, head-
ache, backache and was negative for malaria and sal-
monellosis on rapid diagnostic tests and with a positive
c-ELISA Immunoglobulin M (IgM) or Immunoglobulin
G (IgG) result. A control was defined as a person from
the same study population presenting to the study facili-
ties with history of fever within the same study period
and was negative for brucellosis by c-ELISA IgM and IgG.
Cases were tested for malaria and Salmonellosis because
the diseases are common aetiologies of similar clinical
Laboratory testing
Laboratory testing was carried out at the Kenya Medical
Research Institute using IgM and IgG ELISA kit sourced
from Immuno-Biological Laboratories, America (Min-
neapolis, Minnesota). All assays were conducted as per
manufacturer’s instructions. Briefly, human sera were
diluted at 1:10 with sample diluent, added to microtitre
plates pre-coated withBrucella antigen (Brucella abor-
tus, strain W99; lysate of a NaCl extract) and incubated
at room temperature for 1h. Conjugate was added and
incubated for 30min before adding substrate. e con-
jugate–substrate reaction was terminated after 20 min
by adding a stop solution. Sample optical densities
(ODs) were read at 450nm. Equivocal samples were not
included in analysis.
Questionnaire andinterviewing
A study nurse was stationed in each of the three facilities.
Once a patient was identified as a member of the study
population during triage (coming from a study house-
hold), they were directed to the study nurse who exam-
ined them and administered a standard questionnaire
pre-loaded on a personal data assistant. e question-
naire collected information on patients’ demographic,
risk factors, history of illness and point of care test
results. Informed consent was obtained from all study
Data analysis
A number of risk factors were investigated including con-
sumption of goats, sheep, or cow milk, drinking fresh
livestock blood, livestock ownership, herding and slaugh-
tering animals, handling skins and hides, and helping in
animal delivery. Bivariate analysis was performed using
the Chi squared test. Variables with a p-value 0.10 in
the bivariate analysis were included in a multivariate
logistic regression model. Adjusted odds ratios and the
corresponding 95% confidence intervals along with the
p-values were reported with significance level being set
at 5%. Multivariate logistic regression was used to iden-
tify risk factors associated with brucellosis and to esti-
mate the magnitude of the adjusted odds ratios (aORs)
for each factor while controlling for other confound-
ing factors. Only the significant variables were included
in the model to control for confounding and get a final
logistic regression model. Only those variables that had
a p-value < 0.05 in the final model were considered sta-
tistically significant. Data were analyzed using Statistical
Analysis Software (SAS) version 9.2.
Patient socio‑demographic characteristics
Of the 236 participants from the study population who
met the inclusion criteria, majority, 64% were majority
female. Participants had a mean age of 40years (stand-
ard deviation = 16.9, range 7–75) and 129 (54.6%) of
them were enrolled in the case control study, including
43 cases and 86 controls. e mean age for the cases was
48.7 (standard deviation = 20, range = 10–85) years while
that of the controls was 37.6 (standard deviation = 18.8,
range = 8–72). Among cases, 70% (n = 30) were between
20 and 59 years. e dominant gender for both cases
(62.7%) and controls (58.1%) was female. Majority of both
cases and controls were non-skilled laborers and there
was no significant difference in socio-demographic char-
acteristics (sex, religion, occupation, marital status and
education) between cases and controls besides age.
Clinical information
Sixty percent of the cases presented at-least 7days after
the onset of the first symptom while 37% presented
between 11 and 60 days after onset of symptoms. e
mean number of days between onset of symptoms and
visit to hospital was 12days (standard deviation = 13.3).
e most commonly reported symptoms by both cases
were headache (83.7%) back pains (62.8%) and joint pains
(60.6%). is was similar to the symptoms reported by
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Muturietal. BMC Res Notes (2018) 11:865
the controls; headache (82.6%), back pains (47.7%) and
joint pains (69.8%).
Bivariate analysis
On bivariate analysis, consuming un-boiled cow milk,
drinking fresh blood, slaughtering animals (cattle, wild
animals), assisting goats in giving birth, handling ani-
mal hides were associated with increased risk of brucel-
losis (p-value 0.1). Of these factors, handling skins and
hides, assisting goats with delivery, and consuming un-
boiled goat milk were significantly associated with dis-
ease (p-value 0.05). Having cattle in the household was
found to be protective as shown in the Table1.
Multivariable analysis results
On multivariate logistic regression analysis consum-
ing un-boiled cow milk (OR 7.7, 95% CI 1.5–40.1) and
assisting animals in delivery (OR 3.7, 95% CI 1.1–13.5)
remained significantly associated with brucellosis as
shown in Table2.
Our case–control study identified consumption of raw
cow milk, assisting livestock in delivery, and handling
animal hides as risk factors on bivariate analysis. How-
ever, only assisting livestock in delivery and drinking
un-boiled cow milk remained significant risk facts after
multivariate analysis. e association between assisting
animals with delivery and increased risk of infection has
been reported in other studies carried out in similar set-
tings in East Africa [23, 33] Chad [34], the Middle East
[35] and in Turkey [36, 37]. Given that Brucella spp. are
known to have a predilection for reproductive organs
particularly placenta and aborted fetuses, it is logical that
assisting animals in delivery increases risk of infection
[23]. e risk of brucellosis associated with consump-
tion of un-boiled milk has been well documented [22, 23,
38]. Interestingly, even though most of the pastoralists
around the world know about this risk, majority of them
still consume raw milk as a tradition and for cultural rea-
sons [39]. Although opinion differs between authors on
whether direct contact with livestock (assisting in deliv-
ery, milking and feeding) or indirect contact with live-
stock (consumption of animal products) is a stronger risk
factor, we found greater association with disease from
consuming animal products than direct contact with ani-
mal. is finding is in agreement with other studies car-
ried out within the East Africa region [23, 40, 41]. Studies
have shown that consumption of unpasteurized milk is
a common practise in Kenya, including communities in
urban areas such as where 77% of households reported
the risky practice [42]. Some studies show education and
occupation are significant risk factors contrary to our
Table 1 Bivariate analysis of risk factors for human
Variable Controls
(n = 86) Cases
(n = 43) Crude
OR(95% CI) p-value
Yes Yes
Consume fresh goat milk
More than 3 times a
week 14 14 2.4 (1.0–6.0) 0.114
Less than 3 times a
week 21 8 0.9 (0.4–2.4)
No 51 21 1.0
Consume cow milk
Boiled 82 32 7.7 (1.5–40.1) 0.016
Unboiled 2 6
Consume fresh sheep milk
More than 3 times a
week 1 1 2.1 (0.1–34.1) 0.756
Less than 3 times a
week 4 3 1.6 (0.3–7.3)
No 81 39 1.0
Drink fresh blood
Yes 6 7 2.6 (0.8–8.3) 0.098
No 80 36
Had cattle in the household
Yes 55 26 0.1 (0.0–0.9) 0.035
No 31 17
Slaughter cattle at home
Occasionally 54 32 2.3 (0.8–6.2) 0.102
Never 23 6
Herding sheep
Several times a week 16 14 2.0 (0.5–7.8) 0.196
Occasionally 49 19 0.9 (0.2–3.2)
Never 9 4 1.0
Assisting sheep in delivery
Several times a week 1 1 4.0 (0.2–72.2) 0.116
Occasionally 45 30 2.7 (1.0–6.9)
Never 28 7 1.0
Slaughtering goats at home
Several times a week 1 1 4.8 (0.3–90.3) 0.115
Occasionally 53 33 3.0 (1.0–8.6)
Never 24 5 1.0
Assisting goats in delivery
Occasionally 48 31 3.7 (1.3–10.7) 0.043
Never 29 5 1.0
Slaughtering wild animals
Yes 1 3 0.073
No 82 40 6.4 (0.6–63.2)
Cleaning animal barns
Several times a week 57 5 0.4 (0.1–1.3) 0.132
Occasionally 19 14
Handle animal hides
Yes 30 23 2.1 (1.2–4.5) 0.043
No 56 20
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Muturietal. BMC Res Notes (2018) 11:865
data that shows there was no significant difference on
the two variables between cases and controls. A possible
explanation is the study area is a rural, predominantly
Maasai agro-pastoral community where most house-
holds practise a traditional livestock rearing lifestyle. is
means that cases and controls have similar occupation
and education levels.
Conclusion andrecommendations
e findings of this study show a significant association
between infection and consumption of unpasteurized
milk and assisting animals with delivery. is findings
show that animal handlers; primarily farmers and animal
health workers and people who consume unpasteurized
milk; a common practise in Kenya, are at the greatest
risk. We recommend Public health education on bru-
cellosis transmission and prevention, specifically use of
protective personal equipment when assisting animals in
delivery and boiling of milk should be offered to farmers
and the general public, respectively.
ere were some limitations to the study. Case–control
studies are prone to selection bias but we took measures
to minimise the same; we recruited cases and controls
from households participating in an ongoing cohort study
of brucellosis in livestock. is meant cases and controls
were recruited from households with similar character-
istics, which in turn minimises selection bias. Another
significant limitation is the limited sample size. e study
only recruited cases and controls from an ongoing study
that had recruited 810 households with 4792 people; this
limited the number of study participants who could be
included in our analysis.
AOR: adjusted odds ratio; C-ELISA: competitive enzyme-linked immunosorb-
ent assay; CI: confidence interval; IgM: immunoglobulin M; IgG: immunoglob-
ulin G; OD: optical density; OR: odds ration.
Authors’ contributions
MM was part of the team that designed the study, conducted the field work,
data analyses, and did the first draft of the manuscript. AB, AM, EO, DM, ZG, PN
ZN, SM, KN supervised the field work and contributed to the study design and
manuscript. KN supervised all the work, analyses, and manuscript writing; and
designed the study. All authors read and approved the final manuscript.
Author details
1 Kenya Zoonotic Disease Unit–Ministry of Agriculture, Livestock and Fish-
eries and Ministry of Health, P.O. Box 20811-00202, Nairobi, Kenya. 2 Food
and Agriculture Organization of the United Nations, Nairobi, Kenya. 3 Paul G.
Allen School for Global Animal Health, Washington State University, Pullman,
WA, USA. 4 Kenya Medical Research Institute, Nairobi, Kenya. 5 Kenya Field
Epidemiology and Laboratory Training Program, Nairobi, Kenya. 6 County Gov-
ernment of Kajiado, Kajiado, Kenya. 7 Jomo Kenyatta University of Agriculture
and Technology, Nairobi, Kenya.
We thank the Kenya Directorate of Veterinary Services, Kenya Ministry of
Health, County Governments of Kajiado, United States’ Centers for Disease
Control and Prevention - Kenya Dr. Peninah Munyua (US CDC) for her mentor-
ship and advice during the study and Kenya Field Epidemiology and Labora-
tory Training Program for their participation in the study.
Competing interests
The authors declare that they have no competing interests.
Availability of data and materials
The dataset used and/or analysed during this study is available from the cor-
responding author on reasonable request.
Consent for publication
Not applicable.
The findings and conclusions in this report are those of the authors and do
not necessarily represent the official position of the United States’ Defence
Threat Reduction Agency or US Centers for Disease Control and Prevention or
the Government of Kenya.
Ethics approval and consent to participate
This study was reviewed and approved by the Kenyatta National Hospital
Ethical Review committee. Cases and controls were enrolled after verbal and
written consent and no personal identifiers were recorded on the question-
naire. After questioning, participants were provided free medical treatment.
Financial support was provided by the United States’ Defence Threat Reduc-
tion Agency, Kenya Ministry of Agriculture, Livestock and Fisheries, Kenya
Ministry of Health and the United States’ Centers for Disease Control and
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in pub-
lished maps and institutional affiliations.
Received: 29 August 2018 Accepted: 29 November 2018
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Table 2 Multivariate logistic regression of factors
associated withbrucellosis
Variable Adjusted OR(95% CI) p-value
Slaughter animals 6.2 (1.1–34.7) 0.350
Handling animal hides 1.3 (0.5–3.6) 0.563
Own cattle 0.6 (0.2–1.6) 0.327
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Assisting livestock in delivery 3.7 (1.1–13.5) 0.050
Drinking un-boiled cow milk 7.7 (1.5–40.1) 0.036
Page 6 of 6
Muturietal. BMC Res Notes (2018) 11:865
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... We found a statistically significant difference between brucellosis and consumption of raw milk (p < 0.0001). This supports the results of other studies indicating either increased risk with consuming raw milk or protective impact of boiling it [30][31][32]. Therefore, a very important step to reduce the incidence is the safe preparation of milk, especially since milk and its products are essential in nutrition. ...
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Introduction: Human brucellosis is one of the most common zoonosis infections, with an important impact on the health and economy worldwide. This study aimed to update and provide epidemiological information on this infection and evaluate Rose Bengal Test, which is used as an essential diagnostic test for brucellosis in Erbil. Methodology: A total of 325 participants seeking care and reporting fever at Rizgary Teaching Hospital were enrolled. Blood samples were tested for Brucella spp. antibodies using Rose Bengal Test and blood culture followed by species identification. A questionnaire was administered to detect the risk factors. Results: The prevalence of probable and confirmed brucellosis was 12.3% (95% CI 9.2-16.3) and 9.5% (95% CI 6.8-13.2) respectively. The majority of cases were in the age group of 18-39 years. Brucellosis was significantly associated with raw milk consumption (OR = 10.3 95% CI 5-22.4) and contact with livestock (OR = 11.5 95% CI 5.6-23.9). Brucella melitensis (58.1%) and Brucella abortus (41.9%) are the dominant species in the area. The sensitivity, specificity, positive predictive value, and negative predictive value of the Rose Bengal Test in comparison to the blood culture were 100%, 96.9%, 77.5 %, and 100% respectively. Conclusions: Brucellosis is a significant cause of fever in Erbil and could be diagnosed by the Rose Bengal Test taking into account the compatibility of clinical features with the positive result. The vaccination of livestock and boiling or pasteurization of milk are essential procedures to reduce the frequency of human brucellosis.
... Constituting transmission risks for brucellosis in humans includes handling hygromas and assisting parturition with bare hands. Such practices are common among men, whilst raw milk consumption by women and men among PC is also common practice (Tialla et al. 2015;Hundal et al. 2016;Muturi et al. 2018). The lack of information on brucellosis is a social and sanitary reality in the Folon region and associated with transmission risk for brucellosis, as demonstrated in a study on risk factors of brucellosis among abattoir personnel and pregnant women in North Cameroon (Awah-Ndukum Men and women in pastoral systems are doubly exposed to brucellosis in different ways. ...
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Brucellosis is an infectious zoonotic disease considered as a threat to public health and pastoralist livelihoods. Symptoms of the disease can lead to gender-specific ailments such as abortions in women and orchitis in men. Pastoralists and their families are at high risk of contracting the disease. Access to health information reinforces existing knowledge and contributes to disease prevention. However, in developing countries, interventions for knowledge sharing on zoonotic diseases predominantly target men. This study aimed to describe mechanisms of knowledge production and transfer on brucellosis according to gender, by assessing the way knowledge affects behaviours of pastoral communities. A community-based cross-sectional survey was conducted among a pastoral community (PC) of the Folon region in north-west Côte d'Ivoire. The study included transhumant pastoralists, sedentary livestock owners, shepherds and their wives. By using mixed methods, 26 semi-structured interviews were conducted, and 320 questionnaires were completed. Statistical analysis with chi-square (χ 2) comparison tests was performed to compare variables between men and women. Findings were interpreted through the concept of specialisation of the social exclusion theory. We found that gender influences access to information on brucellosis and transfer of knowledge on brucellosis appeared gender-biased, especially from veterinarians towards men in the community. The social labour division and interventions of veterinarians through awareness reinforce the knowledge gap on brucellosis between men and women. Men and women consume raw milk, whilst only men in general handle animal discharges with bare hands. To improve the control of brucellosis, knowledge on best practice should be shared with pastoral communities using the One Health approach that encourages mutual learning. Innovative strategies based on gender daily tasks such as safe dairy processing by women and safe animal husbandry to expand their herd for men can be the entry point for the prevention of brucellosis.
... This raises the question as to whether women are at higher risk for the disease than men in those communities. A study conducted in Kenya among clinical cases in Maasai pastoralists showed that the majority of the clinical cases were females (Muturi et al., 2015). Young children are also likely a risk group since they typically consume raw milk and assist in raising shoats. ...
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Background Brucellosis is a neglected bacterial zoonotic disease with substantial economic impact on households. Pastoral communities are a potential risk group due to their way of life being closely interlinked with their large livestock herds. Methodology A semi-structured questionnaire survey was conducted in households in the pastoral Afar and Somali (SRS) regions. All households had people and animals serologically tested for brucellosis. Questions were related to husbandry, consumption habits, and knowledge-attitude-practice towards the disease and zoonoses. Descriptive statistics and logistic analysis were performed to assess potential risk factors for having households with positive humans and/or animals. Result 647 households were included in the survey. Herd brucellosis prevalence was 40.3% (15.9-86.3% in Afar; 4-72.2% in SRS). Over half (56.3%) of the households in Afar and 41.8% in SRS had at least one human reactor. Nearly a quarter of the households (22.8%), recalled abortions in goats in the last 12 months, whereas 52.5% and 50.3% recalled stillborn in all species and membrane retentions respectively. All respondents drank raw milk and discarded animal afterbirths in the direct surroundings with minimal protection. Risk factors for animal reactors were goat herd size, and goat abortion. There was no identified risk factor for having human reactors in households. None of the households knew about brucellosis. Conclusion Although being endemic in Afar and SRS, Brucellosis is not known by the pastoralists. Brucellosis control programs will have to be tailored to the pastoral context, accounting for their mobility, large, multi-species herds and habits.
... It has been shown that humans can get infected with brucellosis through drinking raw milk, raw blood, residing with livestock and handling birth products without gloves [9,37]. Comparably, in other studies, participants reported to engage in raw milk consumption, handling animal birth material and assisting in parturition with bare hands in other countries [8,[38][39][40][41][42][43]. Our study also shows that while some participants were informed of the need to avoid consumption of raw animal products and handling birth materials with bare hands, this did not lead to safer behavior. ...
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Brucellosis is a priority zoonotic disease in Tanzania that causes ill-health in people and affects livestock productivity. Inadequate awareness and behavior risking transmission can impede control efforts. We conducted a cross-sectional survey of 333 livestock owners in three villages in the Kilombero district, Tanzania, to understand their awareness, knowledge and behavior associated with brucellosis. Six Focus Group Discussions (FGDs), two in each village, were conducted, as well as an additional FGD with male herders from one of the villages. Factors associated with knowledge on brucellosis, food consumption and animal husbandry behavior risking transmission of this disease, were identified using generalized linear models. Predictors for knowledge of brucellosis were being male and having a higher educational level, while age was positively associated with a higher level of knowledge. Faith and ethnicity were associated with the performance of practices risking transmission. Following traditional religion and belonging to the Wamaasai ethnicity significantly increased the odds of carrying out these practices. Qualitative analysis gave insight into risk practices and reasoning. Of the 333 respondents, 29% reported that they had experienced abortions in their herds, 14% witnessed retained placentas, and 8% had seen still-births in their cattle within the previous year. However, survey results also showed that only 7.2% of participants had heard about brucellosis as a disease in livestock. Of those who had heard about brucellosis in livestock, 91% associated abortions with it and 71% knew that humans can get infected through raw milk consumption. People overwhelmingly attributed symptoms and transmission of brucellosis in livestock to infection with trypanosomiasis and to supernatural reasons instead. In the community, consumption of raw milk was valued and handling of aborted material was not considered a risk for infection. This agro-pastoralist community holds on to long-held beliefs and practices and lacks understanding of the biomedical concept of brucellosis. Transmission routes and symptoms of brucellosis in humans and livestock are completely unknown. The disparity between risk perception and actual transmission risk related to animal handling and consumption of animal products presents a challenge for disease awareness communication. This study recommends focused community engagement and sensitization to address the limited awareness and misconceptions among agro-pastoralists.
... These data further illustrate that the results of the commercial plate agglutination tests cannot (Table 1) are implausibly high, when evaluated alongside the other tests and the existing literature on the brucellosis prevalence expected in this and other comparable populations 15,51,67 . These estimates are unlikely to be explained by previous exposure in this population [68][69][70][71] , and are more likely due to the low specificity of these tests. The higher sensitivity of RBT protocols (as compared to these commercial plate agglutination tests) is likely to be explained, at least partially, by the standardization of the antigen to OIE specification and the acid buffer used to suspend Rose Bengal stained Brucella cells. ...
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The control of brucellosis across sub-Saharan Africa is hampered by the lack of standardized testing and the use of tests with poor performance. This study evaluated the performance and costs of serological assays for human brucellosis in a pastoralist community in northern Tanzania. Serum collected from 218 febrile hospital patients was used to evaluate the performance of seven index tests, selected based on international recommendation or current use. We evaluated the Rose Bengal test (RBT) using two protocols, four commercial agglutination tests and a competitive enzyme-linked immunosorbent assay (cELISA). The sensitivity, specificity, positive predictive value, negative predictive value, Youden’s index, diagnostic accuracy, and per-sample cost of each index test were estimated. The diagnostic accuracy estimates ranged from 95.9 to 97.7% for the RBT, 55.0 to 72.0% for the commercial plate tests, and 89.4% for the cELISA. The per-sample cost range was $0.69–$0.79 for the RBT, $1.03–$1.14 for the commercial plate tests, and $2.51 for the cELISA. The widely used commercial plate tests performed poorly and cost more than the RBT. These findings provide evidence for the public health value of discontinuing the use of commercial agglutination tests for human brucellosis in Tanzania.
... The multivariable logistic regression analysis of potential risk factors indicated that assisting during birthing or calving was significantly associated with Brucella seropositivity (OR = 9.9, 95% CI = 1.4-72). Assisting in calving or birthing was associated with increased risk of brucellosis in similar settings in Northern Tanzania [67] and in Kenya [68]. Brucella species are known to have a predilection for reproductive organs particularly placenta and aborted foetuses, it is reasonable that assisting animals in delivery would increase risk of infection [62]. ...
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Brucellosis is a bacterial zoonotic disease that has important veterinary and public health consequences as well as economic impact in sub Saharan Africa including Ethiopia. A cross-sectional study was conducted in four selected districts of Borena Pastoral setting in Southern Ethiopia from October 2017 to February 2018 to estimate the prevalence of brucellosis and assess associated risk factors in cattle, sheep, goats and occupationally associated humans. A total of 750 cattle, 882 sheep and goats and 341 human subjects were screened for evidence of brucellosis using the Rose Bengal Test (RBT) with positive results confirmed by Competitive-ELISA(c-ELISA). Structured questionnaires were used for collection of metadata from individual animals, herders and animal attendants to test the association between explanatory and outcome variables. The overall animal level prevalence was 2.4% (95% confidence interval, CI: 1.4–3.7) in cattle, 3.2% (95% CI: 2.1–4.6) in sheep and goats, and 2.6% (95% CI: 1.2–5) in humans occupationally linked to livestock production systems. Herd size, parity, and history of abortion were risk factors associated with Brucella seropositivity (P<0.05) in cattle whereas in sheep and goats the results showed that district, age group, flock size, and history of abortion were significantly associated risk factors with Brucella seropositivity (P<0.05). Assisting calving and presence of seropositive animals in a household (P<0.05) were significantly associated with Brucella seropositivity in humans. Evidence of brucellosis in various animal species and the associated human population illustrates the need for a coordinated One Health approach to controlling brucellosis so as to improve public health and livestock productivity.
... Bovine tuberculosis and Rift Valley fever have been documented in pastoral communities in Ngorongoro-Tanzania (Mangesho et al. 2017), Q-fever in Chad; Mycobacterium bovis infection among the Borana in Ethiopia and pastoralists in Ebonyi-south-eastern Nigeria (Greter et al. 2014;Adesokan et al. 2019); and anthrax outbreaks in Tanzania (Mwakapeje et al. 2018). Consumption of unpasteurised milk and being in direct contact with infected animal tissues like products of abortion and blood increase the risk of transmission of zoonotic diseases such as anthrax, bovine tuberculosis, brucellosis, cysticercosis, echinococcosis, rabies and zoonotic trypanosomiasis, equine encephalitis, hydatidosis/echinococcosis, leishmaniasis and rabies from wildlife to livestock and to humans (WHO 2009;Fevre et al. 2017;Muturi et al. 2018). Major zoonotic infectious diseases which have devastating impacts on health, economy and livelihoods of African pastoralists include among others foot and mouth disease (FMD), Rift Valley fever (RVF) and Middle East respiratory syndrome coronavirus (MERS-CoV). ...
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Abstract Many emerging and re-emerging zoonotic infectious diseases occur in Africa. These are projected to increase as human–animal host contact increases owing to increasing environmental degradation that shrinks nature habitats for wildlife over the continent. The current outbreak of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) responsible for causing coronavirus disease in 2019 (COVID-19) has reinvigorated discourse on the disruptiveness of the zoonotic emerging infectious diseases, owing to their transboundary character. Even as the world focuses on the COVID-19 sweeping pandemic, the Middle East respiratory syndrome coronavirus (MERS)-CoV re-emerged in Saudi Arabia infecting 18 people with five deaths; this has barely received any attention. This outbreak is particularly of concern to the pastoralists in the Horn of Africa, a region that has in recent past seen an increase in camel trade with the Gulf States, especially Yemen and Saudi Arabia. Emerging and re-emerging zoonotic infectious diseases are complex, depend on human–animal–environment interaction and pose a strain on public health systems. There is a need to address these diseases dynamically through a synergistic approach, drawing on expertise from diverse sectors. One Health approach has distinguished itself as an integrative action able to bring together multiple actors on a global, national and local scale to advance the attainment of optimal health outcomes for people, animals and the environment. One Health works by strengthening the preparedness, response, mitigation and monitoring of zoonotic infectious disease risks collaboratively. We opine that as zoonotic emerging and re-emerging infectious diseases continue to rise over pastoral Africa, comprehensive implementation of the One Health approach will be urgently required.
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Human brucellosis remains the commonest zoonotic disease worldwide with more than 500 000 new cases annually. Understanding the biology of Brucella infections and the transmission patterns at the wildlife/livestock/human interface is of paramount importance before implementing any brucellosis control or eradication program in animals, even more so should interventions be justified within One Health. In addition to calling for transdisciplinary collaboration, One Health formally aims to conserve the environment and to promote the well-being of animals. In this opinion paper, the One Health approach of brucellosis is reviewed in the industrialized and the low and middle income countries, highlighting pitfalls and shortcomings of serological studies and discussing the role of urban and peri-urban farming for the re-emergence of brucellosis in the developing world. The role of wildlife as a potential reservoir is highlighted and different management strategies are discussed. Lastly, beyond its role in the control of brucellosis, the ethical dimension of culling wildlife to control disease emergence or spill-back of infections in livestock is discussed. Core transdisciplinary competencies such as values and ethics are critically important in guiding the development of One Health curricula and in continuing professional education, as they describe the knowledge, skills, and attitudes required to be effective. A conceptual framework needs to be developed from inception to knowledge translation. Importantly, transdisciplinary competencies should be developed as an adjunct to discipline-specific areas of expertise, not as a replacement. A profound understanding of the biology of infectious agents is and will always remain a pre-requisite for any sound One Health approach.
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Brucellosis is a major zoonotic infection in Kazakhstan. However, there is limited data on its incidence in humans and animals, and the genetic diversity of prevalent strains is virtually unstudied. Additionally, there is no detailed overview of Kazakhstan brucellosis control and eradication programs. Here, we analyzed brucellosis epidemiological data, and assessed the effectiveness of eradication strategies employed over the past 70 years to counteract this infection. We also conducted multiple loci variable-number tandem repeat analysis (MLVA) of Brucella abortus strains found in Kazakhstan. We analyzed official data on the incidence of animal brucellosis in Kazakhstan. The records span more than 70 years of anti-brucellosis campaigns, and contain a brief description of the applied control strategies, their effectiveness, and their impact on the incidence in humans. The MLVA-16 method was used to type 94 strains of B. abortus and serial passages of B. abortus 82, a strain used in vaccines. MLVA-8 and MLVA-11 analyses clustered strains into a total of four and seven genotypes, respectively; it is the first time that four of these genotypes have been described. MLVA-16 analysis divided strains into 28 distinct genotypes having genetic similarity coefficient that varies from 60 to100% and a Hunter & Gaston diversity index of 0.871. MST analysis reconstruction revealed clustering into "Kazakhstani-Chinese (Central Asian)", "European" and "American" lines. Detection of multiple genotypes in a single outbreak confirms that poorly controlled trade of livestock plays a crucial role in the spread of infection. Notably, the MLVA-16 profile of the B. abortus 82 strain was unique and did not change during 33 serial passages. MLVA genotyping may thus be useful for epidemiological monitoring of brucellosis, and for tracking the source(s) of infection. We suggest that countrywide application of MLVA genotyping would improve the control of brucellosis in Kazakhstan.
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Introduction Zoonotic diseases have varying public health burden and socio-economic impact across time and geographical settings making their prioritization for prevention and control important at the national level. We conducted systematic prioritization of zoonotic diseases and developed a ranked list of these diseases that would guide allocation of resources to enhance their surveillance, prevention, and control. Methods A group of 36 medical, veterinary, and wildlife experts in zoonoses from government, research institutions and universities in Kenya prioritized 36 diseases using a semi-quantitative One Health Zoonotic Disease Prioritization tool developed by Centers for Disease Control and Prevention with slight adaptations. The tool comprises five steps: listing of zoonotic diseases to be prioritized, development of ranking criteria, weighting criteria by pairwise comparison through analytical hierarchical process, scoring each zoonotic disease based on the criteria, and aggregation of scores. Results In order of importance, the participants identified severity of illness in humans, epidemic/pandemic potential in humans, socio-economic burden, prevalence/incidence and availability of interventions (weighted scores assigned to each criteria were 0.23, 0.22, 0.21, 0.17 and 0.17 respectively), as the criteria to define the relative importance of the diseases. The top five priority diseases in descending order of ranking were anthrax, trypanosomiasis, rabies, brucellosis and Rift Valley fever. Conclusion Although less prominently mentioned, neglected zoonotic diseases ranked highly compared to those with epidemic potential suggesting these endemic diseases cause substantial public health burden. The list of priority zoonotic disease is crucial for the targeted allocation of resources and informing disease prevention and control programs for zoonoses in Kenya.
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Background Brucellosis is a debilitating zoonotic disease affecting humans and animals. A comprehensive, evidence-based assessment of literature and officially available data on animal and human brucellosis for Kenya are missing. The aim of the current review is to provide frequency estimates of brucellosis in humans, animals and risk factors for human infection, and help to understand the current situation in Kenya. Methods A total of accessible 36 national and international publications on brucellosis from 1916 to 2016 were reviewed to estimate the frequency of brucellosis in humans and animals, and strength of associations between potential risk factors and seropositivity in humans in Kenya. Results The conducted studies revealed only few and fragmented evidence of the disease spatial and temporal distribution in an epidemiological context. Bacteriological evidence revealed the presence of Brucella (B.) abortus and B. melitensis in cattle and human patients, whilst B. suis was isolated from wild rodents only. Similar evidence for Brucella spp infection in small ruminants and other animal species is unavailable. The early and most recent serological studies revealed that animal brucellosis is widespread in all animal production systems. The animal infection pressure in these systems has remained strong due to mixing of large numbers of animals from different geographical regions, movement of livestock in search of pasture, communal sharing of grazing land, and the concentration of animals around water points. Human cases are more likely seen in groups occupationally or domestically exposed to livestock or practicing risky social-cultural activities such as consumption of raw blood and dairy products, and slaughtering of animals within the homesteads. Many brucellosis patients are misdiagnosed and probably mistreated due to lack of reliable laboratory diagnostic support resulting to adverse health outcomes of the patients and routine disease underreporting. We found no studies of disease incidence estimates or disease control efforts. Conclusion The risk for re-emergence and transmission of brucellosis is evident as a result of the co-existence of animal husbandry activities and social-cultural activities that promote brucellosis transmission. Well-designed countrywide, evidence-based, and multidisciplinary studies of brucellosis at the human/livestock/wildlife interface are needed. These could help to generate reliable frequency and potential impact estimates, to identify Brucella reservoirs, and to propose control strategies of proven efficacy.
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Diseases of zoonotic origin contribute to the burden of febrile illnesses in developing countries. We evaluated serologic evidence of exposure to Bacillus anthracis, Brucella spp., spotted fever group rickettsioses (SFGR), and typhus group rickettsioses (TGR) from samples of persons aged 15-64 years collected during a nationwide human immunodeficiency virus (HIV) serosurvey conducted in 2007 in Kenya. The seropositivity observed for pathogens was B. anthracis 11.3% (141/1,091), Brucella spp. 3.0% (27/968), SFGR 23.3% (191/770), and TGR 0.6% (12/770). On univariate analysis, seropositivity for each pathogen was significantly associated with the following risk factors: B. anthracis with province of residence; Brucella spp. with sex, education level, and wealth; SFGR with age, education level, wealth, and province of residence; and TGR with province of residence. On multivariate analysis, seropositivity remained significantly associated with wealth and province for B. anthracis; with sex and age for Brucella spp; and with sex, education level, and province of residence for SFGR whereas TGR had no significance. High IgG seropositivity to these zoonotic pathogens (especially, B. anthracis and SFGR) suggests substantial exposure. These pathogens should be considered in the differential diagnosis of febrile illness in Kenya.
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Background: Brucellosis remains a neglected zoonotic disease among agro-pastoral communities where unprocessed milk and milk products are consumed. A cross-sectional study was carried out in Kiboga district to determine the seroprevalence and risk factors associated with human brucellosis in communities where livestock rearing in a common practice. Methods: A total of 235 participants were involved in the study. Blood samples from the participants were collected and screened for Brucella using Serum Agglutination Test and Rose Bengal Plate Test. A questionnaire was used to collect data on socio-demographic characteristics and human brucellosis related risk factors. Results: Human Brucella seroprevalence was at 17.0 % (n = 235). The prevalence was highest among males (20.5 %, n = 78) and the elderly - above 60 years (22.2 %, n = 18). Residence in rural areas (OR 3.16, 95 % CI: 1.16-8.56), consuming locally processed milk products (OR 2.54, 95 % CI: 1.12-5.78) and being single (OR 2.44, 95 % CI: 1.05-5.68), were associated with increased risk of brucellosis. Discussion: Human brucellosis seroprevalence was high at 17 %, this was parallel with animal brucellosis prevalence that has been reported to range from 10.2 % to 25.7 % in cattle in the region. The participants were from communities known to habitually consume raw milk and milk products, know to process milk products using bare hands which are major risk factors for brucellosis in humans. This also explains why consumption of unpasteurized milk products was associated with the occurrence of brucellosis in study area. This strengthened the argument that humans get infected through consumption of contaminated animal products as reported in other earlier studies. Males and elderly being more affected because of traditional roles of these groups they play in livestock care and management. The single were also to be more associated to brucellosis, due to the fact that this group consume milk and milk products more as it is readily available in the informal markets as highly nutritious fast foods in this community as also observed in USA. Conclusions: Brucellosis is highly prevalent in Kiboga district, and therefore, an important public health problem. The transmission risk was aggravated by consumption of unpasteurized milk products, residing in rural settings and being single. There is a need to initiate screening, treat infected humans early, and educate the public about risk factors and appropriate preventive measures of brucellosis.
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Brucellosis is a zoonosis of veterinary, public health and economic significance in most developing countries. The disease can result in permanent and disabling sequelae and considerable medical expenses in addition to loss of income due to loss of working hours. A case-control study was conducted in Nyabushozi, Kiruhura district, Uganda, so as to determine the risk factors for transmission of brucellosis to humans in these communities. We conducted a matched case-control study among participants in a previous study who were positive by the standard Serum Agglutination Test with titres ≥1:160. Controls were two neighbors for each case, matched by sex and age. A structured interviewer administered questionnaire was used to collect data on potential risk factors for brucellosis. Categorical variables were presented as proportions and their associations determined by Chi-square test. Bivariate analysis was performed to explore associations between the disease and the risk factors of brucellosis. Conditional logistic regression models were fitted to estimate independent associations between the disease and the risk factors using Odds Ratios and 95 % confidence intervals. A total of 45 cases and 90 controls were interviewed. Of the 45 cases, 21 (46.7 %) were male while 44/90 (48.9 %) of the controls were female. The most significant risk factors for infection being an agro-pastoralist (P = 0.05), consumption of raw cow ghee (P = 0.03) and consumption of unpasteurized milk (P = 0.02). The greatest risk factors for acquiring brucellosis in the study area were being an agro-pastoralist, consumption of raw cow ghee and consumption of unboiled milk. We recommend dissemination of health education packages regarding risks and prevention measures for brucellosis in these communities.
The wildlife of the Greater Yellowstone Ecosystem carries brucellosis, which was first introduced to the area by cattle in the 19th Century. Brucellosis transmission between wildlife and livestock has been difficult to study due to challenges in culturing the causative agent, Brucella abortus . We examined B. abortus transmission between American bison ( Bison bison ), Rocky Mountain elk ( Cervus elaphus nelsoni), and cattle ( Bos taurus ) using variable number tandem repeat (VNTR) markers on DNA from 98 B. abortus isolates recovered from populations in Idaho, Montana, and Wyoming, USA. Our analyses reveal interspecies transmission. Two outbreaks (2007, 2008) in Montana cattle had B. abortus genotypes similar to isolates from bison and elk. Nevertheless, similarity in elk and cattle isolates from the 2008 outbreak suggest that elk are the likely source of brucellosis transmission to cattle in Montana and Wyoming. Brucella abortus isolates from sampling in Montana appear to be divided in two clusters: one exclusive to local Montana elk, cattle, and bison; and another composed mainly of elk and some bison individuals, found in many Wyoming elk, which is consistent with brucellosis having entered Montana via migration of infected elk from Wyoming. Our findings illustrate complex patterns of brucellosis transmission among elk, bison, and cattle as well as the utility of VNTRs to infer the wildlife species of origin for disease outbreaks in livestock.
Early diagnosis and treatment of acute brucellosis cases were targeted by screening the household members of the index cases. We also aimed to describe the causal relations of brucellosis in an endemic region. A cross-sectional study was performed among household members (29 index cases, 113 household members). Brucellosis was diagnosed on the basis of clinical findings, serum agglutinin titer of ≥1/160 in standard tube agglutination test (STA), or a positive blood culture. Index cases were defined as patients who had been admitted to the clinic on suspicion of brucellosis and then confirmed as brucellosis cases. The people who lived in the same house as the index cases were defined as household members. The risk factors for seropositivity were studied by multivariate analysis. Independent variables of gender, consuming fresh cheese, blood groups, dealing with husbandry, and contact with the placenta of infected animals were included to the model. Backward and forward selections were performed. Nineteen out of 113 (17%) screened individuals had agglutination titers ≥1/160. The mean ages of index cases and household members were 43 years (standard deviation [SD] 18) and 29 years (SD 19), respectively. In multivariate analysis, consuming fresh cheese (odds ratio [OR]=3.1, confidence interval [CI] 1.07-9.68, p=0.049), blood group A (OR=2.6, CI 1.18-5.96, p=0.018), contact with the placenta of the infected animals (OR=3.7, CI 1.42-9.68, p=0.007), and age >30 years (OR=2.8, CI 1.25-6.51, p=0.13) were found to be associated with brucellosis. In univariate analysis, the individuals with blood group B were protected from brucella infection (p=0.013). In conclusion, screening of the people in brucellosis-endemic areas should be considered for early diagnosis and treatment. To our knowledge, blood groups were studied for the first time by this study. Higher prevalence of brucellosis among the individuals with blood group A and less prevalence among the individuals with blood group B should be considered for further studies on pathogenesis.