Risk factors for Brucella spp. infection in smallholder household herds

Review of the Current Status on Ruminant Abortigenic Pathogen Surveillance in Africa and Asia

Ruminant abortion events cause economic losses. Despite the importance of livestock production for food security and the livelihoods of millions of people in the world's poorest communities, very little is known about the scale, magnitude, or causes of these abortions in Africa and Asia. The aim of this review was to determine the current status of surveillance measures adopted for ruminant abortigenic pathogens in Africa and Asia and to explore feasible surveillance technologies. A systematic literature search was conducted using PRISMA guidelines for studies published between 1 January 1990 and 1 May 2024 that reported epidemiological surveys of abortigenic pathogens Africa and Asia. A meta-analysis was used to estimate the species-specific sero-prevalence of the abortigenic agents and the regions where they were detected. In the systematic literature search, 39 full-text manuscripts were included. The most prevalent abortigenic pathogens with sero-prevalence greater than 10% were BHV-1, Brucella, Chlamydia abortus, Neospora caninum, RVFV, and Waddlia chondrophila in cattle, BVDV in sheep, and RVFV and Toxoplasma gondii in goats in Africa. In Asia, Anaplasma, BHV-1, Bluetongue virus, Brucella, and BVDV were prevalent in cattle, whereas Mycoplasma was important in goats and sheep.

Seroprevalence, associated risk factors, and molecular detection of bovine brucellosis in rural areas of Egypt

The study was carried out on six villages in northern Egypt to evaluate the epidemiological situation of bovine brucellosis among 989 unvaccinated household cattle by Rose Bengal Plate Test (RBPT) and indirect ELISA (iELISA) and to investigate the existence of Brucella DNA using real-time PCR in 100 milk and 100 sera from seropositive cattle and 50 sera from seronegative cattle. The overall seroprevalence was 20.7% and 23.7% by RBPT and iELISA, respectively. Based on the iELISA results, the seroprevalence was significantly (P < 0.05) higher in the village II (34.7%) and cattle > 7 years (30.1%). More males than females were non-significant seropositive (P = 0.6). There was 95% agreement between RBPT and iELISA, although iELISA showed a higher positivity rate (23.7%, 95% CI: 0.21-0.26) than RBPT (20.7%, 95% CI: 0.18-0.24). DNA of Brucella was confirmed in 16 milk samples by IS711 qPCR from seropositive cattle, however, no Brucella DNA was detected in serum samples tested positive and negative. Brucella abortus was the only species detected based on the alkB gene. Prevalence is highly related to the sampling site and the age of the animals. In conclusion, although qPCR is more accurate and commonly used in the diagnosis of most infectious diseases but in this situation iELISA is preferred and recommended for continuous screening and animal movement restriction and vaccination protocols, especially in high-risk areas.

Seroprevalence of Bovine Brucellosis in Selected Sites of Central Highland of Ethiopia

Background

Brucellosis is a contagious, economically significant bacterial disease that affects animals worldwide and is one of the most neglected zoonotic diseases in the world. The disease poses a barrier to the trade of animals and animal products, represents a public health hazard, and is an impediment to free animal movement.

Methods

A cross-sectional study was carried out from December 2019 to May 2020 in order to determine seroprevalence and identify potential risk factors for brucellosis in dairy cows in the Central Highlands of Ethiopia with recent cases of abortion. Purposive sampling was carried out on the farms and kebeles in question to screen for recent cases of abortion in dairy cows. For the purpose of performing serological testing, 352 blood samples from dairy cattle were obtained. The Rose Bengal Plate test was used to initially screen the serum samples, and the Complement Fixation test was utilized as a confirmatory test.

Results

Using combined RBPT and CFT tests, the overall seroprevalence of bovine brucellosis was 0.6% (95% CI: 0.16-2.09). Retained fetal membrane (OR = 32.74, p = 0.006), market-based stock replacement (OR = 16.55, p = 0.002), breeding method (OR = 7.58, p = 0.027), and late stage of abortion (OR = 14.74, p = 0.0002) are all significantly associated risk factors.

Conclusion

The present seroprevalence study revealed that brucellosis is prevalent at a lower rate among dairy cattle in the study areas. However, there is a possible risk of brucellosis transmission in dairy cattle and the exposed human population in research locations because no control measures were put in place there. Implementing a test and slaughter method with compensation for farmers is advised due to the low prevalence of bovine brucellosis in government-owned and small-holder farms.

Cross-Sectional Study of Seroprevalence and Associated Risk Factors of Bovine Brucellosis in Selected Districts of Jimma Zone, South Western Oromia, Ethiopia

Bovine brucellosis is one of the most widespread but neglected zoonotic diseases in developing countries where it is an endemic and growing problem causing public health impacts. Developing a cost-effective control strategy of the disease can only be guaranteed by knowledge of the disease epidemiology that defines its risk profiles. Hence, this study was designed to evaluate epidemiological aspects of bovine brucellosis in selected districts of Jimma zone. A cross-sectional study with multistage sampling techniques was conducted on 424 cattle to evaluate its seroprevalence. Likewise, 114 households were included for the investigation of risk factors. SPSS version 20 for data analysis and C-ELISA test for antibody detection were used. Moreover, the chi-square test for univariable analysis and logistic regression model for multivariable analysis were employed to assess association between seropositivity and risk factors. From this study, 3.3% (95% CI: 1.82-5.48) and 12.3% (95% CI: 6.88-19.75) seroprevalence of the disease was detected with the highest proportion found at Kersa district (6.5 (95% CI: 1.37-17.90) and (21.4 (95% CI: 4.66-50.80)) followed by Seka Chokorsa (1.76 (95% CI: 0.37-5.07) and (6.7 (95% CI: 1.40-18.27)) and Mana (1.75 (95% CI: 0.21-6.20) and (7.1 (95% CI: 0.88-23.50)) at individual animals and herd levels, respectively. Cattle of poor body condition, pregnant, and cows with history of abortion and repeat breeding were found 4.8 (95% CI: 2.00-22.74), 4.3 (95% CI: 1.43-13.04), 3.3 (95% CI: 1.07-10.21), and 2.7 (95% CI: 1.86-8.15) times more likely seropositive than their counterparts, respectively. Besides these, mixed feeding style was highly associated with seropositive reactors than separate feeding (AOR = 8.3; 95% CI: 1.76-38.99). These findings depicted substantial areas to be addressed in implementation of appropriate and immediate control actions and establishment of intervention mechanisms of bovine brucellosis.

Importance of brucellosis control programs of livestock on the improvement of one health

Brucellosis not only represents an important health restraint on livestock but also causes high economic losses in many developing countries worldwide. Despite considerable efforts made for the control of brucellosis, the disease is still spreading in many regions (such as the Middle East) where it represents one of the most important health hazards impacting both animals and humans. The present review aims to investigate the efficacy of veterinary control programs regarding brucellosis, with a special focus on current prevention, control, and eradication approaches. The reasons for unsuccessful control programs such as the absence of highly effective vaccines and non-certified bulls are also debated, to understand why the prevalence of brucellosis in livestock is not decreasing in many areas despite considerable efforts taken to date. The importance of governmental and regional investment in brucellosis control remains one of the main limiting factors owing to the limited budget allocated to tackle this disease. In this context, one health concept has generated novel comprehensive approaches with multiple economic implications across the livestock industry and public health. However, the implementation of such global preventive strategies appears to be a key issue for many endemic and low-income countries. According to the collected data, epidemiological contexts including management and trade systems along with well-defined agro-ecological zones should be evaluated in brucellosis endemic countries to improve milk production and to enhance the sustainability of the livestock sector at both national and regional levels.

Bovine Brucellosis in Gauteng, South Africa: Seroprevalence amongst Cattle Handlers and Variables Associated with Seropositive Cattle Herds, 2014-2016

In South Africa, the prevalence of cattle handler exposure to Brucella on cattle farms is unknown and risk factors and cattle symptoms associated with infected cattle herds are unavailable. To address this gap, a case-control study of cattle herds was conducted in Gauteng province and farm workers and veterinary officials were tested for exposure to Brucella. Seroprevalence amongst farm workers exposed to case herds ranged from 4.0% (BrucellaCapt®) to 16.7% (IgG ELISA®), compared to those exposed to control herds, where seroprevalence ranged from 1.9% (BrucellaCapt®) to 5.7% (IgG ELISA®). Seroprevalence amongst veterinary officials was significantly greater compared to farm workers exposed to case herds for the outcome RBT+ IgM- IgG+ (OR = 11.1, 95% CI: 2.5-49.9, p = 0.002) and RBT- IgM- IgG+ (OR = 6.3, 95% CI: 2.3-17.3, p < 0.001). Risk factors associated with being an infected herd were: being a government-sponsored farm vs. private farm (OR 4.0; 95% CI: 1.4-11.3; p = 0.009), beef vs. dairy herd (OR 7.9; 95% CI: 1.4-44.9; p = 0.020), open vs. closed herd (OR 3.3; 95% CI: 1.1-10.4; p = 0.038) and the presence of antelope on the farm (OR 29.4; 95% CI: 4.0-218.2; p = 0.001). Abortions (OR = 5.1; 95% CI: 2.0-13.3; p < 0.001), weak calves in the herd (OR = 8.0; 95% CI: 2.6-24.4; p < 0.001), reduction in number of calves born (OR = 9.0; 95% CI: 2.1-43.6; p < 0.001), reduction in conception rate (OR = 3.9; 95% CI: 0.8-18.3; p = 0.046), hygromas in cattle (p = 0.011) and farmers reporting brucellosis-like symptoms in their farm workers or in him/herself (OR = 3.4; 95% CI: 1.3-8.7; p = 0.006) were more likely to be associated with Brucella infected herds than control herds. This evidence can be used in strategic planning to protect both human and herd health.

Seroprevalence and Associated Risk Factors of Bovine Brucellosis in District Gujranwala, Punjab, Pakistan

Simple Summary

Our study estimated the seroprevalence of brucellosis in bovine herds and identified the important risk factors associated with the occurrence of the disease at livestock farms. A total of 220 sera from 46 bovine herds of district Gujranwala, Punjab, Pakistan, was collected and subjected to brucellosis screening by serology. It resulted in 58.7% herd-based and 22.7% individual animal-based seroprevalence. Age, herd size and previous history of abortion came out as associated risk factors. Strict biosecurity, personal protection, quarantine measures and routine screening are recommended at livestock-holdings/farms, whereas disease awareness and pasteurization of milk are recommended for the general population to prevent zoonosis.

Abstract

Bovine brucellosis is a contagious zoonotic disease that causes economic losses through abortion and infertility. A cross-sectional study was designed to determine the seroprevalence and associated risk factors of bovine brucellosis in district Gujranwala of Punjab, Pakistan. A total of 220 bovine sera (112 from buffaloes, 108 from cattle) from 46 unvaccinated herds were collected. Parallel testing by the Rose Bengal Plate Test (RBPT) and Indirect Enzyme-linked Immunosorbent Assay (I-ELISA) showed a 58.7% (27/46) herd-level and 22.7% (50/220) animal-level seroprevalence. Seroprevalence was higher (p < 0.001, OR = 7.62) in adult animals (37.2%) compared to younger animals (4.9%). A herd size of >10 animals (p = 0.021, OR = 7.83), less housing space (p = 0.037, OR = 6.39) and history of abortion at the farm (p = 0.023, OR = 5.6) were found as risk factors associated with the seropositivity of brucellosis. There was a substantial agreement between the RBPT and I-ELISA results (Cohen’s kappa coefficient (κ) = 64.16, percent agreement = 89.5%). In conclusion, a relatively higher seroprevalence was found compared to the previous reports from the country. Standardization and validation of the advanced diagnostic tests would be needed. Biosecurity, personal protection, quarantine measures and routine screening of animals at the farm level and disease awareness programs and consumption of pasteurized milk in the human population will be helpful in preventing the transmission/zoonosis of the disease.

Bovine brucellosis - a comprehensive review

Brucellosis is a zoonotic disease of great animal welfare and economic implications worldwide known since ancient times. The emergence of brucellosis in new areas as well as transmission of brucellosis from wild and domestic animals is of great significance in terms of new epidemiological dimensions. Brucellosis poses a major public health threat by the consumption of non-pasteurized milk and milk products produced by unhygienic dairy farms in endemic areas. Regular and meticulous surveillance is essentially required to determine the true picture of brucellosis especially in areas with continuous high prevalence. Additionally, international migration of humans, animals and trade of animal products has created a challenge for disease spread and diagnosis in non-endemic areas. Isolation and identification remain the gold standard test, which requires expertise. The advancement in diagnostic strategies coupled with screening of newly introduced animals is warranted to control the disease. Of note, the diagnostic value of miRNAs for appropriate detection of B. abortus infection has been shown. The most widely used vaccine strains to protect against Brucella infection and related abortions in cattle are strain 19 and RB51. Moreover, it is very important to note that no vaccine, which is highly protective, safe and effective is available either for bovines or human beings. Research results encourage the use of bacteriophage lysates in treatment of bovine brucellosis. One Health approach can aid in control of this disease, both in animals and man.

Prevalence and Spatial Distribution of Animal Brucellosis in Central Punjab, Pakistan

Brucellosis is an important zoonotic disease of animals and humans caused by bacteria of the genus Brucella. Brucellae are Gram-negative intracellular bacteria which infect a wide variety of animals including goats, sheep, buffaloes, cows, pigs, and wildlife. The objectives of this study were to determine the seroprevalence and spatial distribution of brucellosis in Central Punjab, Pakistan. A total of 1083 blood samples of goats, sheep, buffaloes, and cows were collected from 38 villages of four districts (Kasur, Faisalabad, Lahore, and Okara) of Punjab, Pakistan, and screened for brucellosis by Rose Bengal Plate test (RBPT) and PCR confirmed. Epidemiological, demographic data and GPS coordinates for every sample were collected. By using interpolation of the Aeronautical Reconnaissance Coverage Geographic Information System (Arc GIS), a surface plot was generated applying inverse distance weight (IDW). It was found that 35 (3.23%) serum samples were positive for brucellosis. In eight (61.5%), six (75%), seven (87.5%), and eight (89%) villages, positive goats, sheep, buffaloes, and cattle were detected, respectively. In general, older animals are more often positive for brucellosis. In goats bucks were more often RBPT positive than females while in sheep, buffaloes, and cattle more females were positive. The spatial distribution of brucellosis shows that it is widely distributed in the western region of the study area in goats and in the South-West region in sheep. Similarly, for buffaloes it is restricted to the south-east and north-west regions, and in cattle brucellosis is present in western region of study area only. Reflected by this study, brucellosis poses a risk for livestock in developing countries due to lack of awareness by officials, owners, and consumers, and control measures are missing. A risk map of brucellosis was generated to develop effective strategies for awareness rising and to improve the quality of control programs in Pakistan.

Bovine brucellosis in Pakistan; an analysis of engagement with risk factors in smallholder farmer settings

A cross-sectional study was conducted to estimate the seroprevalence of bovine brucellosis in smallholder farms in seven regions in Pakistan, identify herd and individual level risk factors for seropositivity and assess the level of engagement of farmers with risk factors. In total, 1063 cattle and buffalo belonging to 420 herds in seven districts were sampled. The Rose Bengal test (RBT), indirect enzyme-linked immunosorbent assay (I-ELISA) and competitive enzyme-linked immunosorbent assay (C-ELISA) were used for the serological diagnosis of bovine brucellosis on all the serum samples. The associations between herd-and animal-level risk factors and seropositivity were investigated using logistic regression analyses. In addition, herd management practice scores, created to quantify the number of management practices undertaken that pose a risk for Brucella transmission, were calculated and compared between seropositive and negative herds within each district. Overall herd and animal prevalence were estimated to be 16.2% (95% CI, 13-20%) and 8.7% (95% CI, 7.2-10.6%), respectively, across all districts sampled. Herds with a history of last trimester abortion were found to be more likely to be positive than herds without such history (OR = 2.06, 95% CI, 1.09-3.89), providing validation of our findings and identifying that clinical disease is occurring in this region. It was also identified that herds with five to eight buffalo (OR = 3.80, 95% CI, 1.69-8.49), and those with more than eight buffalo (OR = 3.81, 95% CI, 1.51-9.58) were more likely to be positive for Brucella than those with less (one to two and three to four) buffaloes present in the herd. The presence of other domestic animals at the farm and purchasing animals in last year were found to have no association with seropositivity. The findings of this study support the need for the development of targeted intervention strategies specific to the disease status of each district.

Sero-prevalence of Bovine Brucellosis and associated risk factors in mbeya region, Southern highlands of Tanzania

A cross-sectional study was conducted to establish the seroprevalence of brucellosis and associated risk factors in indigenous and exotic breeds of cattle from 178 farms in Mbeya region. A total of 1211 cattle (929exotic cattle from 108 commercial farms and 282 indigenous cattle from 70 traditional farms) were tested for Brucella antibodies using the Rose Bengal Plate Test (RBPT) and competitive Enzyme Linked Immunosorbent Assay (c-ELISA) as screening and confirmatory tests, respectively. The overall animal-level seroprevalence was 9.3%; 11.3% (95% CI: 9.4-13.5) in indigenous cattle and 2.8% (95% CI:1.4-5.6) in exotic cattle. Further, the overall herd level seroprevalence was 32.0%; 50.5% (95% CI: 40.9-59.9) in indigenous cattle and 4.2% (95% CI: 1.3-12.4) in exotic cattle. Infections were higher in cattle aged 6-10 years old, (39.8%; 95% CI: 31.2-49.1) followed by those aged 1-5 years (5.8%; 95% CI: 4.8-6.6) and 11-15years old (2.7%; 95% CI: 0.8-8). When compared to cattle sampled from herds size of 1-50, those sampled from the herd sizes of 51-100 and 101-150 had higher odds of brucellosis seropositivity [(OR=3.6, CI: 1.76-7.16, p<0.001) and (OR=3.0, CI: 1.09-8.04, p=0.033). The odds of seropositivity in animals which calved on pasture was 3.0 (CI: 1.1-7.8, p=0.028) compared to those that calved at home. Brucella seroprevalence was also observed to vary according to districts, with Mbarari district recording the highest (45.4%). It is evident from the study that Brucellosis is present in Mbarari, Mbeya and Momba districts of Mbeya Region. The findings of this study provide some baseline data that could contribute to the design and implementation of brucellosis control measures in the study areas.

Seroprevalence of brucellosis in cattle and selected wildlife species at selected livestock/wildlife interface areas of the Gonarezhou National Park, Zimbabwe

A study was conducted to investigate seroprevalence and risk factors for Brucella species infection in cattle and some wildlife species in communities living at the periphery of the Great Limpopo Transfrontier Conservation Area in south eastern Zimbabwe. Three study sites were selected based on the type of livestock-wildlife interface: porous livestock-wildlife interface (unrestricted); non-porous livestock-wildlife interface (restricted by fencing); and livestock-wildlife non-interface (totally absent or control). Sera were collected from cattle aged≥2years representing both female and intact male animals. Sera were also collected from selected wild ungulates from Mabalauta (porous interface) and Chipinda (non-interface) areas of the Gonarezhou National Park. Samples were screened for Brucellaantibodies using the Rose Bengal plate test and confirmed by the complement fixation test. Data were analysed by descriptive statistics and multivariate logistic regression modelling. In cattle, brucellosis seroprevalence from all areas was 16.7% (169/1011; 95% CI: 14.5-19.2%). The porous interface recorded a significantly (p=0.03) higher seroprevalence (19.5%; 95% CI: 16.1-23.4%) compared to the non-interface area (13.0%; 95% CI: 9.2-19.9%).The odds of Brucellaseropositivity increased progressively with parity of animals and were also three times higher (OR=3.0, 2.0<OR<4.6, p<0.0001) in cows with history of abortion compared to those without.Brucella antibodies were detected in buffaloes; 20.7% (95% CI: 13.9-29.7%) form both study sites, but no antibodies were detected from impalas and kudus. These results highlight the importance of porous interface in the interspecies transmission of Brucella species and that independent infections may be maintained in buffalo populations. Thus, brucellosis control aimed at limiting animal inter-species mixing may help reduce the risk of human brucellosis in interface areas. Further studies should aim at establishing subspecies identity and direction of possible transmission of brucellosis between wildlife and livestock.

Serological survey for Brucella antibodies in donkeys of north-eastern Nigeria

A cross-sectional epidemiological study was conducted to determine seroprevalence and risk factors influencing the presence of Brucella antibodies in donkeys of Borno State, north-eastern Nigeria. The study aimed at providing baseline information that may be used in planning a control policy against equine brucellosis. Blood samples were collected from 601 donkeys, comprised of 374 males and 227 females from the six agricultural zones of the state between March 2013 and September 2014. The sera obtained were tested for Brucella antibodies using Rose Bengal plate test (RBPT) and competitive enzyme-linked immunosorbent assay (cELISA). Of the 601 donkeys tested, 43 (7.2%) and 40 (6.7%) were seropositive by RBPT and cELISA, respectively. A seroprevalence of 8.6% was obtained in male and 3.5% in female donkeys. According to age, the highest seroprevalence of 9.6% was obtained from donkeys of age group 4-6 years. With respect to pregnancy status, a higher seroprevalence (6.8%) was obtained from pregnant donkeys compared to 3.8% obtained from the non-pregnant ones. There were statistically significant associations between the presence of antibodies and sex (p < 0.05) and the presence of antibodies and age (p < 0.05) of the studied donkeys. However, no statistically significant association (p > 0.05) was observed between the pregnancy status and presence of antibodies. The study concludes that Brucella infection is present in donkeys in all the agricultural zones of the state. The relatively high seroprevalence (7.2%) obtained is of public health concern because of the close interaction between donkeys, ruminants, and humans in the study area.

Assessment of community awareness and risk perceptions of zoonotic causes of abortion in cattle at three selected livestock–wildlife interface areas of Zimbabwe

A study was conducted to assess the awareness of cattle abortions due to brucellosis, Rift Valley fever (RVF) and leptospirosis, and to compare frequencies of reported abortions in communities living at the periphery of the Great Limpopo Transfrontier Conservation Area in southeastern Zimbabwe. Three study sites were selected based on the type of livestock–wildlife interface: porous livestock–wildlife interface (unrestricted); non-porous livestock–wildlife interface (restricted by fencing); and livestock–wildlife non-interface (totally absent or control). Respondents randomly selected from a list of potential cattle farmers (N = 379) distributed at porous (40·1%), non-interface (35·5%) and non-porous (26·4%), were interviewed using a combined close- and open-ended questionnaire. Focus group discussions were conducted with 10–12 members of each community. More abortions in the last 5 years were reported from the porous interface (52%) and a significantly higher per cent of respondents from the porous interface (P < 0·05) perceived wildlife as playing a role in livestock abortions compared with the other interface types. The odds of reporting abortions in cattle were higher in large herd sizes (odds ratio (OR) = 2·6; 95% confidence interval (CI) 1·5–4·3), porous (OR = 1·9; 95% CI 1·0–3·5) and non-porous interface (OR = 2·2; 95% CI 1·1–4·3) compared with livestock–wildlife non-interface areas. About 21·6% of the respondents knew brucellosis as a cause of abortion, compared with RVF (9·8%) and leptospirosis (3·7%). These results explain to some extent, the existence of human/wildlife conflict in the studied livestock–wildlife interface areas of Zimbabwe, which militates against biodiversity conservation efforts. The low awareness of zoonoses means the public is at risk of contracting some of these infections. Thus, further studies should focus on livestock–wildlife interface areas to assess if the increased rates of abortions reported in cattle may be due to exposure to wildlife or other factors. The government of Zimbabwe needs to launch educational programmes on public health awareness in these remote areas at the periphery of transfrontier conservation areas where livestock–wildlife interface exists to help mitigate the morbidity and mortality of people from some of the known zoonotic diseases.

Seroprevalence and risk factors associated with bovine brucellosis in the Potohar Plateau, Pakistan

Background

The seroprevalence and risk factors of bovine brucellosis were studied at animal and herd level using a combination of culture, serological and molecular methods. The study was conducted in 253 randomly selected cattle herds of the Potohar plateau, Pakistan from which a total of 2709 serum (1462 cattle and 1247 buffaloes) and 2330 milk (1168 cattle and 1162 buffaloes) samples were collected. Data on risk factors associated with seroprevalence of brucellosis were collected through interviews using questionnaires. Univariable and multivariable random effects logistic regression models were used for identifying important risk factors at animal and herd levels.

Results

One hundred and seventy (6.3%) samples and 47 (18.6%) herds were seropositive for brucellosis by Rose Bengal Plate test. Variations in seroprevalence were observed across the different sampling sites. At animal level, sex, species and stock replacement were found to be potential risk factors for brucellosis. At herd level, herd size (≥9 animals) and insemination method used were important risk factors. The presence of Brucella DNA was confirmed with a real-time polymerase chain reaction assay (qRT-PCR) in 52.4% out of 170 serological positive samples. In total, 156 (6.7%) milk samples were positive by milk ring test. B. abortus biovar 1 was cultured from 5 positive milk samples.

Conclusion

This study shows that the seroprevalence of bovine brucellosis is high in some regions in Pakistan. Prevalence was associated with herd size, abortion history, insemination methods used, age, sex and stock replacement methods. The infected animal may act as source of infection for other animals and for humans. The development of control strategies for bovine brucellosis through implementation of continuous surveillance and education programs in Pakistan is warranted.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-017-2394-2) contains supplementary material, which is available to authorized users.

Serological survey of bovine brucellosis in Fulani nomadic cattle breeds (Bos indicus) of North-central Nigeria: Potential risk factors and zoonotic implications

A cross sectional study was conducted to investigate seroprevalence and associated risk factors of bovine brucellosis in Fulani nomadic herds in the 3 agro-ecological zones of Niger State, North-central Nigeria between January and August 2013. A total of 672 cattle in 113 herds were screened for Brucella antibodies using Rose Bengal Plate Test (RBPT) and confirmed by Lateral flow Assay (LFA). Data on herd characteristics and zoonotic factors were collected using structured questionnaire administered on Fulani herd owners. Factors associated with Brucella infection were tested using Chi-square test and multivariable logistic model. The overall cattle-level seroprevalence was 1.9% (95% CI: 1.1-3.2) with highest in agro-zone C (3.2%). Herd-level seroprevalence was 9.7% (95% CI: 5.23-16.29) and highest in agro-zone C (13.5%). Sex and agro-ecological zones were significantly (P<0.006 and P<0.01, respectively) associated with Brucella abortus seropositivity. Herd composition, abortion in herd, exchange of bulls for mating, introduction of new cattle, and socio-cultural practices were significantly associated with brucellosis occurrence. Inhalation of droplets from milk of infected cows, and drinking raw milk were less likely [OR 0.27; 95% CI: 0.09-0.82 and OR 0.27; 95% CI: 0.08-0.99, respectively] not to predisposed to brucellosis in humans. Eating infected raw meat, and contact with infected placenta were more likely [OR 7.49; 95% CI: 2.06-28.32 and OR 5.74; 95% CI: 1.78-18.47, respectively] to be risks for the disease in humans. These results highlighted the important risk factors for bovine brucellosis in Fulani herds. Thus, brucellosis control programs which take these factors into consideration will be beneficial.

Prevalence of and factors associated with Brucella sero-positivity in cattle in urban and peri-urban Gulu and Soroti towns of Uganda

Brucellosis is a key zoonosis of major public health, animal welfare and economic significance, and is endemic in livestock in Uganda. A cross-sectional epidemiological study was carried out to estimate the sero-prevalence of brucellosis and identify factors associated with sero-positivity in cattle in urban and peri-urban Gulu and Soroti towns of Northern and Eastern Uganda, respectively. A total of 1007 sera and data on biologically plausible risk factors from 166 herds and their spatial locations, were collected from cattle reared in urban and peri-urban Gulu and Soroti towns of Uganda. The sera were analyzed using indirect ELISA and sero-positive reactors confirmed by competitive ELISA. Multivariable models were used to investigate for risk factors. The overall animal-level and herd-level sero-prevalence was 7.5% (76/1007, 95% Confidence Interval (CI): 6.15-9.4%) and 27.1% (45/166, 95% CI: 20.9-34.3%), respectively. Herd-level sero-prevalence was significantly (P<0.001) higher in Soroti than Gulu. In Gulu town, sero-positivity increased with an increase in herd size (P=0.03) and age (P=0.002), and was higher in cattle brought in from western Uganda (P<0.0001). In Soroti town, introduction of new cattle into a herd was significantly (P=0.027) associated with herd sero-positivity. There was a geographically differential risk (clustering) of Brucella sero- positivity in herds in Soroti, while sero-positivity was homogeneously distributed in Gulu. The data highlight brucellosis occurrence and major risk factors for its transmission in cattle in urban and peri-urban areas.

The Prevalence of Brucellosis in Cattle, Goats and Humans in Rural Uganda: A Comparative Study

A cross-sectional study was conducted to determine the presence of brucellosis in cattle, goats and humans in farms from south-western Uganda and identify risk factors associated with brucellosis in these three host groups. Data and serum samples were collected from 768 cattle, 315 goats and 236 humans, with 635 samples of bovine milk, from 70 farms in two different study areas in south-western Uganda. Sera from livestock were tested with the Rose Bengal Plate test, using B. abortus and B. melitensis antigens, and human sera were tested with a commercial IgG/IgM lateral flow assay. Milk samples were tested using the OIE-approved milk ring test. Screening tests for brucellosis were positive in 14% of cattle serum, 29% of bovine milk, 17% of goat serum and 11% of human serum samples. There were significant differences in the test prevalence of brucellosis by study site, with levels higher in the study area near Lake Mburo National Park than in the study area near Queen Elizabeth National Park. Multivariable regression models identified risk factors associated with increasing test positivity at the individual and farm levels for cattle, goats and humans. Positive associations were seen between increasing seropositivity of brucellosis in goats, cattle and humans. Results of multivariable analyses suggest that improvements in farm biosecurity and hygiene may reduce the risk of brucellosis on the farm and suggest a role for ticks in bovine brucellosis. Although cattle are the focus of brucellosis control in Uganda, the significant associations between seropositivity in humans and seropositivity in goats suggest that brucellosis in goats may be an important contributor to the epidemiology of the disease on the farm.

MODELING THE TRANSMISSION DYNAMICS OF DAIRY CATTLE BRUCELLOSIS IN JILIN PROVINCE, CHINA

Dairy cattle brucellosis is a chronic bacterial disease, which is caused by Brucella abortus and mainly characterized by abortion in dairy cattle. With the rapid development of breeding industry of milk cows in China, the infectious cases of dairy cattle brucellosis show an increasing trend. Particularly in Jilin province, the annual number of the positive cases of dairy cattle was only 3 cows in 1987, and went up to 168 cows in 2005. Based on the situation of the brucellosis infection in Jilin province, we propose an Susceptible-Exposed-Infected-Virus (SEIV) dynamical model with outside transferred amount to describe the transmission of brucellosis amongst dairy cattle in this paper. We calculate the basic reproduction number R0 and prove that the equilibria are globally stable. Moreover, using the real data of nearly 20 years in Jilin province, we estimate the parameter values in the system. As a result, we can predict the number of infections as time increases. According to the prediction for the next 30 years, we can conclude that the disease will persist if we just take existing measures. If culling, sterilizing and decreasing the number of outer importing are used together, dairy cattle brucellosis will be well controlled.