Seroprevalence of brucellosis and its associated risk factors in cattle from smallholder dairy farms in Zimbabwe

A novel Bayesian Latent Class Model (BLCM) evaluates multiple continuous and binary tests: A case study for Brucella abortus in dairy cattle

Bovine brucellosis, primarily caused by Brucella abortus, severely affects both animal health and human well-being. Accurate diagnosis is crucial for designing informed control and prevention measures. Lacking a gold standard test makes it challenging to determine optimal cut-off values and evaluate the diagnostic performance of tests. In this study, we developed a novel Bayesian Latent Class Model that integrates both binary and continuous testing outcomes, incorporating additional fixed (parity) and random (farm) effects, to calibrate optimal cut-off values by maximizing Youden Index. We tested 651 serum samples collected from six dairy farms in two regions of Henan Province, China with four serological tests: Rose Bengal Test, Serum Agglutination Test, Fluorescence Polarization Assay, and Competitive Enzyme-Linked Immunosorbent Assay. Our analysis revealed that the optimal cut-off values for FPA and C-ELISA were 94.2 mP and 0.403 PI, respectively. Sensitivity estimates for the four tests ranged from 69.7% to 89.9%, while specificity estimates varied between 97.1% and 99.6%. The true prevalences in the two study regions in Henan province were 4.7% and 30.3%. Parity-specific odds ratios for positive serological status ranged from 1.2 to 2.2 for different parity groups compared to primiparous cows. This approach provides a robust framework for validating diagnostic tests for both continuous and discrete tests in the absence of a gold standard test. Our findings can enhance our ability to design targeted disease detection strategies and implement effective control measures for brucellosis in Chinese dairy farms.

Seroprevalence and assessment of public awareness of Brucella spp., Toxoplasma gondii and Chlamydia abortus in small ruminants from selected smallholder commercial farms of Zimbabwe

Brucella spp., Toxoplasma gondii, and Chlamydia abortus have long been recognized as zoonoses and significant causes of reproductive failure in small ruminants globally. A cross-sectional study was conducted in August 2020 to determine the seroprevalences of Brucella spp., Toxoplasma gondii and Chlamydia abortus in 398 small ruminants from four districts of Zimbabwe (Chivi, Makoni, Zvimba, and Goromonzi) using Indirect-ELISAs. A structured questionnaire was used to assess the knowledge, attitudes, and practices of 103 smallholder farmers towards small ruminant abortions, Brucella spp., T. gondii and C. abortus, and to obtain a general overview of the significance of small ruminant reproductive failure(s) on their livelihoods. The overall seroprevalences were: 9.1% (95% CI: 6.4-12.3) for Brucella spp., 6.8% (95% CI: 4.5-9.7) for T. gondii and 2.0% (95% CI: 0.9-3.9) for C. abortus. Location, age, parity, and abortion history were associated with Brucella spp. seropositivity. Location was also associated with both T. gondii and C. abortus seropositivity. The questionnaire survey established that 44% of respondents had recently faced reproductive disease challenges within their flocks, with 34% correctly identifying abortion causes and only 10%, 6% and 4% having specific knowledge of Brucella spp., C. abortus and T. gondii, respectively. This study provides the first serological evidence of Brucella spp. in small ruminants since 1996 and builds the evidence on small ruminant toxoplasmosis and chlamydiosis in Zimbabwe. Evidence of these zoonoses in small ruminants and the paucity of knowledge shows the need for a coordinated One Health approach to increase public awareness of these diseases, and to establish effective surveillance and control measures. Further studies are required to establish the role these diseases play in small ruminant reproductive failure(s), to identify the Brucella spp. detected here to species/subspecies level, and to assess the socio-economic impact of reproductive failure in livestock among marginalised rural communities.

Seroprevalence, and molecular detection of Brucella abortus in cattle tissues from an abattoir in Namibia

Brucellosis is a worldwide zoonosis that is endemic in Namibia. This study estimated seroprevalence of brucellosis, and determined the presence of Brucella infection in slaughtered cattle using the genus-specific 16-23S rRNA interspacer PCR (ITS-PCR), and the species-specific AMOS-PCR. Between December 2018 and May 2019, sera (n = 304), pooled lymph nodes (n = 304), and individual spleen (n = 304) were collected from slaughtered cattle from 52 farms. Sera were tested for anti-Brucella antibodies using the Rose Bengal test (RBT), and the complement fixation test (CFT). Seroprevalence was 2.3% (7/304) (RBT) and 1.6% (5/304) (CFT). Prevalence of positive herds was 9.6% (5/52). Lymph node (n = 200) and spleen (n = 200) samples from seronegative cattle tested negative for Brucella spp. DNA on ITS-PCR, but Brucella spp. DNA was detected in lymph nodes (85.7%, 6/7) and spleen (85.7%, 6/7) from RBT positive cattle. ITS-PCR confirmed isolates from lymph node (51.4%, 4/7) and spleen (85.7%, 6/7) as Brucella spp.; while AMOS-PCR and Brucella abortus species specific (BaSS) PCR confirmed the isolates as Brucella abortus, and field strains, respectively. Provision of adequate protective gear, and the promotion of brucellosis awareness among abattoir workers is recommended to prevent zoonotic infection.

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.

Occurrence and Risk Factors of Brucellosis in Commercial Cattle Farms from Selected Districts of the Eastern Coast Zone, Tanzania

Brucellosis is a disease of major socio-economic importance worldwide, particularly in low-income countries. This retrospective study aimed to estimate seroprevalence and risk factors associated with brucellosis in commercial cattle farms in the eastern coast zone of Tanzania (ECZT). A total of 1,052 serum samples collected from 20 commercial farms were subjected to rose bengal plate test (RBPT) and indirect enzyme-linked immunosorbent assay (i-ELISA). Descriptive analysis was employed to determine frequencies and proportions. To establish risk factors, a multivariate logistic regression analysis was carried out using a backward elimination procedure, following a univariate analysis, with 0.1 set as a cut-off point for the selection of putative risk factors. Agreement between RBPT and i-ELISA was determined using a Kappa coefficient (κ). The overall animal-level seroprevalence was 25.9% based on i-ELISA. Logistic regression analysis revealed that odds of infection were significantly higher in females (OR = 1.8, 95% CI: 1.2-2.5, p = 0.002) and in young animals than in adults (OR = 3.6, CI: 2.1-6.2, p < 0.001). In addition, odds of infection were higher during the wet season (OR = 3.4, CI: 3.2-5.2, p < 0.001), in cattle reared in rural farms (OR = 4.8, CI: 2.0-11.5, p < 0.001), in cattle reared in areas, not in contact with wildlife (OR = 2.9, CI: 1.4-2.3, p = 0.004), and in medium-sized farms (OR = 12.5, CI: 6.9-22.9, p < 0.001). These findings confirm that bovine brucellosis was prevalent among commercial cattle farms in the ECZT, posing a serious public health concern to the community living in these settings. The one health approach should be adopted for effective control of brucellosis.

Occurrence and risk factors of brucellosis among domestic animals: an artificial neural network approach

Brucellosis is a zoonotic infectious disease with a worldwide distribution. This cross-sectional study aimed to determine the occurrence of Brucella in milk and blood samples of ruminants and the importance factors associated with animal brucellosis in Eastern Iran. A total of 200 paired samples, including blood (100) and milk (100), were obtained from the goats, sheep, and cows in Eastern Iran. Serum agglutination (SAT) and 2-mercapto ethanol (2-ME) tests were performed on the sera. A multiplex-polymerase chain reaction (m-PCR) assay was performed to identify the following species of Brucella, including B. abortus biovar 1, 2, 4, 3b, 5, 6, and 9, B. abortus S19, B. melitensis, and B. melitensis Rev.1 vaccine strain. B. abortus RB51 vaccine strain was also investigated in a second PCR assay. Risk factors for infection with Brucella spp. including the effect of abortion, contact with the wild animals, herd type, age, and previous vaccination in predicting blood contamination with B. abortus biovar 1, 2, and 4 were modeled by use of the artificial neural network. A total of 23 samples were seropositive regarding SAT and 2-ME tests. In total, B. abortus was detected in 35% and 15% of blood and milk samples, respectively, by the m-PCR assay. One sample of each of milk and blood was detected to have B. melitensis. Some samples were simultaneously contaminated with two Brucella species or two biovars of B. abortus. B. abortus S19 and B. melitensis Rev.1 vaccine strains were also detected in milk and blood samples. The sensitivity and specificity of the ANN model were 81% and 62%, respectively. In conclusion, B. abortus had higher frequency than B. melitensis in blood and milk samples. ANN determined herd type, previous vaccination, and age of the animal as the largest predictors of blood contamination with B. abortus.

Bovine Brucellosis: Epidemiology, Public Health Implications, and Status of Brucellosis in Ethiopia

Brucellosis is a globally distributed zoonotic disease that causes serious problems in developing countries such as Ethiopia. Brucella abortus is the primary cause of brucellosis in cattle, and Brucella melitensis and Brucella suis also occasionally cause Brucella infection in cattle. Abortion and the retained fetal membrane are typical signs in females, whereas orchitis and bursitis are the known signs in male cattle. Brucellosis is typically transmitted to healthy cattle by direct or indirect contact with diseased cattle or their discharges. Humans can acquire brucellosis through the consumption of unpasteurized milk or milk products, and through contact with diseased cattle or their discharges. The occurrence of bovine brucellosis is affected by different factors related to the management system, host, and environmental factors. In Ethiopia, the occurrence of brucellosis is high in pastoral and mixed cattle management systems, wherever humans live closely with cattle and so have a higher probability of picking up the Brucella organism. The most suitable technique in the management of Brucella infection is the vaccination of young female cattle. Brucella abortus can also be eradicated by the isolation of diseased cattle, administration of immunizing agents, and test-and-slaughter methods. Therefore, it is important to implement applicable management techniques and to increase public awareness about the transmission of brucellosis, and further research should be conducted on brucellosis in high-risk groups.

Seroprevalence of camel brucellosis in Qatar

Brucellosis is a significant zoonotic disease and one of the most common neglected diseases worldwide. It can infect a wide range of domestic and wild animal species. Infected animals are usually culled, causing substantial economic losses to animal owners and the country's economy in general. The disease is endemic among cattle, sheep, and goats in many countries around the Middle East and prevalent in most Gulf Cooperation Council countries, comprising a significant public health risk in the region. This study investigated the seroprevalence of brucellosis among camels in Qatar. Two hundred and forty-eight samples were collected from dromedary camels from 28 farms across the entire country. Each sample was tested for Brucella antibodies with both Rose Bengal and competitive enzyme-linked immunosorbent assay. Only samples that tested positive by both tests were considered seropositive for brucellosis. The overall prevalence was (20.6%, 95% CI, 15.7-26.1). The association between sex and seropositivity was slightly significant (Χ² = 4.32, P = 0.04), with higher seroprevalence in females. Camels below breeding age (i.e., < 4 years old) showed decreased seropositivity (3.4%, 95% CI, 0.1-17.8), compared to (22.8%, 95% CI, 17.4-29.0) seropositivity in camels ≥ 4 years of age, with a significant association between age groups and seropositivity (P = 0.02). Our results indicate that the seroprevalence of brucellosis in Qatar's camels is alarming, mandating more efforts to control the disease. The findings of this study will aid in selecting better effective measures to control camel brucellosis in Qatar. Further studies need to be conducted on Brucella infection among camels to determine the predisposing risk factors and the steps that should be followed to control brucellosis.

Seroprevalence of Bovine Brucellosis and Associated Risk Factors in Western Ethiopia

Background

Brucellosis is a contagious bacterial disease, which affects domestic animals, humans, and wildlife in Ethiopia and other countries.

Methods

A cross-sectional study design using a simple random sampling technique was conducted in Diga, Guto, Gida, and Sibu Sire districts of East Wollega Zone, Western Oromia, from November 2019 to July 2020 to determine the prevalence of bovine brucellosis and identify associated risk factors. A lottery method was used during serum collection and risk factors identified during interview.

Results

A total of 1152 serum samples were collected from cattle of 6 months age and above. Serum samples were tested by enzyme linked immunosorbent assay (I-ELISA). An overall seroprevalence of brucellosis was 1.82% (21/1152). Statically significant variation (P<0.05) in seroprevalence of bovine brucellosis was recorded among potential risk factors such as breed [P≤0.05; OR:8.905; CI:1.568–50.573], parity [P≤0.05; OR:0.017; CI:0.042–5.195], retained fetal membrane [P≤0.001; OR:0.018; CI:0.00–2.169], and abortion history [P≤0.001; OR:0.030; CI:0.004–0.212]. Conversely, seroprevalence variations in sex, district, villages, body condition score, and age were statistically insignificant (P>0.05).

Conclusion

The current study revealed bovine brucellosis is posing a threat to livestock with no strict control and prevention scheme in place. Therefore, public awareness creation about the zoonotic importance of the disease is crucial and the Government should establish legislation, support, control, and prevention of the disease recommended.

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.

Circulating Brucella species in wild animals of the Serengeti ecosystem, Tanzania

BACKGROUND

Brucellosis is a bacterial zoonosis of public health and economic importance worldwide. It affects a number of domestic animals, wild animals and humans. Human brucellosis originates from either livestock or wildlife. The species of Brucella circulating in wild animals in Tanzania is largely unknown due to insufficient surveillance. This study was carried out to identify Brucella species found in selected wildlife hosts in the Serengeti ecosystem.

METHODOLOGY

The study used a total of 189 archived samples that were obtained from cross-sectional studies previously conducted between 2000 and 2017 in the Serengeti ecosystem in Tanzania. Whole blood, serum and amniotic fluid collected from buffalos, lions, wildebeest, impala, zebra and hyena were available for DNA extraction. Multiplex polymerase chain reaction for B. abortus, B. melitensis, B. ovis and B. suis (AMOS PCR) and quantitative real-time PCR (qPCR) targeting the bcsp31 and IS711 genes for Brucella genus detection and the IS711 targets alkB for B. abortus and BMEI1162 for B. melitensis were used to detect Brucella strains.

RESULTS

Out of the 189 samples tested, 12 (6.35 %) and 22 (11.6 %) were positive to AMOS-PCR and qPCR, respectively. Most of the positive samples were from lions (52.6 %) and buffaloes (19.6 %). Other animals that were positive included: wildebeest (13.6 %), impala (13.6 %), zebra (4.5 %) and hyena (4.5 %). Out of 22 positive samples, 16 (66.7 %) were identified as B. abortus and the other six samples did not amplify for neither B. abortus nor B. melitensis.

CONCLUSIONS

The detection of Brucella DNA in archived wild animal samples shows testing potential of samples collected from this population. The zoonotic species B. abortus and B. melitensis detected in wild animals have previously been reported in livestock and humans in the region. The findings suggest that, due to the contact network, some of the identified wild animal hosts in this study could be reservoirs for infections in domestic animals and humans within the Serengeti ecosystem while others are likely dead-end hosts. One Health control strategies and continuous surveillance programs in other wildlife reserved areas should be implemented to help predicting transmission in livestock and humans in the region.

Documenting the absence of bovine brucellosis in dairy cattle herds in the southern region of Malawi and the associated knowledge, attitudes and practices of farmers

There is paucity of Brucella prevalence data in Malawi. For this reason, a cross-sectional study was conducted, from 06 January 2020 to 27 February 2020, to estimate the seroprevalence of brucellosis in dairy cattle herds amongst smallholder farmers, government and private dairy farms in the southern region. A total of 529 serum samples were screened for anti-Brucella antibodies using the Rose Bengal test (RBT) and a competitive enzyme-linked immunosorbent assay (cELISA). A pre-tested electronic (Epicollect tool, Wellcome Sanger Institute, United Kingdom) questionnaire was administered to 378 smallholder farmers to assess their knowledge, attitudes and practices towards brucellosis. Descriptive statistics were used to analyse the data in Microsoft Excel^® and Statistical Package for Social Sciences (SPSS^®) version 21. No animal tested positive for presence of anti-Brucella antibodies, indicating 0% prevalence (individual and herd levels). The majority (94.2%; 95% confidence interval [CI]: 91.8–96.5) of smallholder farmers had never heard about brucellosis. Furthermore, assisting during parturition without protective equipment (41.3%; 95% CI: 36.3–46.2) and using bulls for breeding (75%; 95% CI: 70.2–78.9) were amongst the common risk practices that were identified. We could not detect brucellosis in this study that indicates the disease could be very rare or even absent in the dairy cattle herds of the southern region of Malawi. However, further Brucella studies need to be conducted in cattle, small livestock, wildlife and humans to document the true status of brucellosis in the country. Brucellosis surveillance, monitoring, awareness and preventive measures are required to maintain this favourable situation.

Prioritizing smallholder animal health needs in East Africa, West Africa, and South Asia using three approaches: Literature review, expert workshops, and practitioner surveys

Managing the health needs of livestock contributes to reducing poverty and improving the livelihoods of smallholder and pastoralist livestock keepers globally. Animal health practitioners, producers, policymakers, and researchers all must prioritize how to mobilize limited resources. This study employed three approaches to prioritize animal health needs in East and West Africa and South Asia to identify diseases and syndromes that impact livestock keepers. The approaches were a) systematic literature review, b) a series of expert workshops, and c) a practitioner survey of veterinarians and para-veterinary professionals. The top constraints that emerged from all three approaches include endo/ ectoparasites, foot and mouth disease, brucellosis, peste des petits ruminants, Newcastle disease, and avian influenza. Expert workshops additionally identified contagious caprine pleuropneumonia, contagious bovine pleuropneumonia, mastitis, and reproductive disorders as constraints not emphasized in the literature review. Practitioner survey results additionally identified nutrition as a constraint for smallholder dairy and pastoralist small ruminant production. Experts attending the workshops agreed most constraints can be managed using existing veterinary technologies and best husbandry practices, which supports a shift away from focusing on individual diseases and new technologies towards addressing systemic challenges that limit access to veterinary services and inputs. Few research studies focused on incidence/ prevalence of disease and impact, suggesting better incorporation of socio-economic impact measures in future research would better represent the interests of livestock keepers.

Seroprevalence of Bovine Brucellosis in Ethiopia: Systematic Review and Meta-Analysis

Brucellosis is an infectious and widespread zoonotic disease caused by bacteria of the genus Brucella and can induce considerable human suffering and huge economic losses in animals. Thus, the aim of this study was to conduct a systematic review and meta-analysis on the seroprevalence of bovine brucellosis in Ethiopia. PubMed, Science Direct, African Journals Online, and Google Scholar were used to search the articles. All references were screened and articles, which reported seroprevalence of bovine brucellosis in Ethiopia were included in the study. Meta-analysis using random-effects models was made to calculate the pooled seroprevalence of brucellosis. This review included 15 papers. The estimated pooled seroprevalence of brucellosis was found to be 3.0% (95% CI: 2.0, 4.0). The subgroup analysis showed that there was a statistically significant association between the disease and geographical location, setting, laboratory technique employed and study years. Also, there was some evidence of publication bias (Egger's test, p = 0.0003) on studies reporting the prevalence of brucellosis in Ethiopia. This review proves a high seroprevalence of brucellosis in the country and appropriate control strategies are recommended. Moreover, further study on the risk factors is also required to develop cost-effective preventive strategies.

Seroprevalence and risk factors of brucellosis and the brucellosis model at the individual level of dairy cattle in the West Bandung District, Indonesia

Background and Aim

Brucellosis is a zoonotic bacterial infectious disease. West Bandung is a center for dairy farming in West Java Province District and endemic for brucellosis. The aim of the study was to determine the prevalence, the associated risk factors, and the brucellosis model at the individual level of dairy cattle in the West Bandung District.

Materials and Methods

The research was conducted through a cross-sectional study. The samples were collected from the serum blood of dairy cattle. Data obtained from the questionnaire were used to investigate risk factors. Multistage random sampling was applied as the sampling technique; therefore, a sample size of 540 cows was selected. The number of farms and cattle on each farm was calculated using a variant effect design of the farm as well as 108 farms was selected with five cattle samples per farm. The results in regard of the research sample acquisition in the West Bandung District included 588 dairy cows from 116 farms, exceeds the number of samples calculated (540 dairy cows and 108 farms). The rose Bengal test (RBT) and the complement fixation test (CFT) were performed for brucellosis testing. Data associated with brucellosis cases at the individual level of the dairy cattle were analyzed using descriptive statistics univariate, bivariate with Chi-square, and odds ratio (OR). Moreover, multivariate logistic regression was used for the analysis during modeling.

Results

The results showed that the prevalence of brucellosis at the individual level in the West Bandung District was 5.10%. Risk factors associated with brucellosis in cattle included the history of abortion (p=0.000; OR=9.9), the history of placental retention (p=0.000; OR=6.6), the history of endometritis (p=0.000; OR=5.5), the history of stillbirth (p=0.043; OR=3.0), the history of pregnancy abortion age at 7-8 months (p=0.000; OR=15.2), and the history of pregnancy abortion at the age of 4-6 months (p=0.007; OR=3.8). The model of brucellosis in dairy cows was the following: = -3.2843+3.41033 the history of pregnancy abortion at the age of 7-8 months +2.54503 the history of pregnancy abortion at the age of 4-6 months +1.86185 age of cattle >2 years - 1.0469 Calving interval 12 months. The model showed the factors that were associated with brucellosis at the individual level of dairy cattle included the history of pregnancy abortion at the age of 7-8 months (β=+3.41033; OR=30.3), the history of pregnancy abortion at the age of 4-6 months (β=+2.54503; OR=12.7); age of cattle >2 years (β=+1.86185; OR=1.2), and Calving interval ≤12 months (β=-1.04691; OR=0.34).

Conclusion

The results of this research showed that the prevalence of brucellosis at the individual level of dairy cattle in the West Bandung district was 5.10%. The risk factors could contribute to the increase of the brucellosis cases, that is, the history of pregnancy abortion at the age of 7-8, the history of pregnancy abortion at the age of 4-6 months, and the age of cattle >2 years. The risk factors can be decreased in the brucellosis cases, that is, calving intervals ≤12 months.

A retrospective sero-epidemiological survey of bovine brucellosis on commercial and communal farming systems in Namibia from 2004 to 2018

Cattle production is the major livestock production activity and the mainstay of Namibia's economy. Sustained beef exports are contingent on a sound sanitary environment where diseases such as brucellosis are under control. In this retrospective study, 49,718 bovine brucellosis testing results from 2004 to 2018 were analyzed to determine the proportion of sero-positive cattle and herds, and the spatial distribution of positive reactors from commercial and communal areas. In total, 244 positive reactors were identified based on the Rose Bengal Test (RBT) and the Complement Fixation Test (CFT) in series, giving an overall proportion of infected animals of 0.49% (244/49,718; 95% CI, 0.43-0.56%) and an overall proportion of infected herds of 9.26% (78/842; 95% CI, 7.49-11.41%). There was a higher proportion of sero-positive communal herds (33.09%) and cattle (10.27%) than commercial herds (4.67%) and cattle (0.24%; p < 0.05). Annually, the proportion of positive reactors was 0-1.37% in the commercial area and 0-52.38% in the communal areas, with a clear decline in positive reactors in the communal areas. Within the commercial sector, the proportion of positive reactor dairy, beef, and export cattle was 0.19% (51/27,067; 95% CI, 0.14-0.25%), 0.30% (48/16,098; 95% CI, 0.22-0.40%), and 0.33% (16/4811; 95% CI, 0.20-0.54%), respectively. Abortions were found to be the major reason for Brucella testing in the communal areas. About 12.65% (96/759) of abortion-linked sera tested positive in the communal areas, but none were positive in beef or dairy cattle. Widespread vaccination of cattle and robust planned surveillance is recommended to reduce the incidence of the disease, its associated production losses and public health risk.

Seroprevalence and risk factors for bovine brucellosis in the Chittagong Metropolitan Area of Bangladesh

Brucellosis is a neglected endemic zoonosis in Bangladesh and has a significant impact on public health and animal welfare of dairy farming as well as dairy farm economics. A cross‐sectional study was conducted to evaluate the seroprevalence of and risk factors for brucellosis in dairy cattle in the Chittagong metropolitan area (CMA) of Chittagong, Bangladesh. We collected serum samples (n = 158) from six randomly selected dairy farms in the CMA between February and November, 2015. The Rose Bengal Plate Test (RBPT) and a competitive ELISA (cELISA) were used as the screening and confirmatory tests respectively. Farm level and animal level demographic and risk factor data were collected using a questionnaire. The risk factors were analysed using a multivariable logistic regression with random effects. The overall seroprevalences of antibodies against brucellosis in cattle were 21.5% (34/158) and 7.6% (12/158) based on parallel and serial interpretation of the two tests respectively. Our results revealed that 20.3% (32/158) samples were positive using the RBPT and 8.9% (14/158) were positive using the cELISA. The within‐herd seroprevalence ranged from 10% to 26.3% and 5 to 20.7% using the RBPT and cELISA tests respectively. The odds of seropositivity were significantly higher in lactating cows (OR: 2.59; 95% CI: 1.02–6.55), cows producing less than 2 litres of milk (OR: 29.6; 95% CI: 4.3–353.8), cow producing 2–12 litres of milk (OR: 4.8; 95% CI: 1.1–33.4) and cows with reproductive disorders (OR: 3.2; 95% CI: 1.2–10.1). About 7.6% (12/158) and 1.3% (2/158) of cattle were found to be infected with acute and chronic brucellosis respectively. Based on these results, we suggest that cows that have reproductive disorders and are producing little milk should be prioritized for brucellosis screening in CMA. The screening tests should be used to control brucellosis in cattle in order to protect animal welfare, human health and to minimize the economic losses.

Seroprevalence and associated factors of brucellosis and Q-fever in cattle from Ibarapa area, Oyo State, South-western Nigeria

Introduction

a cross-sectional study was conducted to determine the seroprevalence and associated factors of brucellosis and Q-fever among cattle in a rural setting in Oyo State, Nigeria.

Methods

one hundred and fourty nine serum samples (24 males; 125 female) from 16 cattle herds were collected and screened. The Rose Bengal Plate test (RBPT) and competitive Enzyme-Linked Immunosorbent Assay (cELISA) were used for brucellosis while indirect Enzyme-Linked Immunosorbent Assay (iELISA) was used for Q-fever. Further, a checklist was used to collect data on cattle sampled. Data were analyzed using STATA 12.

Results

serum analysis revealed that 11.4% (17/149) and 6.7% (10/149) were seropositive by RBPT and cELISA respectively for brucellosis, while 23.5% (35/149) were seropositive by iELISA for Q-fever. A significant association was detected between cattle age (OR=27.7; 95% CI: 2.34-449.86), herd size (OR=10.53; 95% CI: 1.85-60.53) and seropositivity to Brucella infection. Also, there was a significant association between breed (OR=6.69; 95% CI: 1.7-28.74), herd size (OR=4.25; 95% CI: 1.31-13.85) of cattle and seropositivity to Coxiella burnetii infection. Importantly, the only significant associated factor to cattle herd seropositivity to Brucella and C. burnetii infections was the method of handling aborted foetuses.

Conclusion

the study revealed that brucellosis and Q-fever are prevalent among cattle in the study area. Thus, there is a need for further studies to provide better insight into the epidemiology of both diseases and particularly Q-fever. This becomes imperative in the study area and generally in Nigeria given the dearth of information about the diseases in pastoralist communities who are at grave risk of infection at the human-animal-ecosystem interface.

The global epidemiology of Brucella infections in terrestrial wildlife: A meta-analysis

Brucellosis is a widespread zoonotic disease with serious consequences on human and animal health. Brucella infections were reported in many terrestrial wild animals, from subtropical and temperate regions to arctic regions. In many areas, the epidemiology of brucellosis in wildlife is closely associated with the occurrence of the disease in livestock. Some wild species may contribute to the re-introduction of Brucella infections in livestock (spillback), even in officially brucellosis-free (OBF) regions. Through meta-regression analysis, this study draws a global picture of the prevalence of Brucella spp. in terrestrial wild animals, trying to determine most affected subgroups as well as preferential sampling and screening methods. For this purpose, a literature search was carried out among publications published from 1983 to 2019. Different subgroups were compared according to animal species, feeding, gender, age as well as the method used for sampling and for brucellosis diagnostic. To determine heterogeneity of studies, chi-squared test was used and a random-effects model (REM) estimated the pooled prevalence among subgroups. A total of 68 publications, comprising 229 data reports/studies, were selected. The most-reported Brucella species in wildlife was Brucella abortus, and the highest prevalence rate was found in American bison, Bison bison (39.9%) followed by Alpine ibex, Capra ibex (33%). Serology was the most widely applied diagnostic approach (66%), while PCR appeared to be highly sensitive (36.62% of positive results). The gender of animals showed no significant association with the prevalence of brucellosis (p > .05). Blood samples and visceral organs constituted the great majority of specimen used for the detection of Brucella spp., while lymph nodes showed a high prevalence of positive samples (94.6%). The present study provides insight into the global epidemiology and enzootic potential of brucellosis in wild terrestrial animals worldwide, aiming at helping the appropriate authorities to strengthen prevention, surveillance and control strategies.

Evaluation of the sensitivity and specificity of the lateral flow assay, Rose Bengal test and the complement fixation test for the diagnosis of brucellosis in cattle using Bayesian latent class analysis

This study was conducted to evaluate the sensitivity (Se) and specificity (Sp) of the Rose Bengal test (RBT), complement fixation test (CFT), the serum lateral flow assay (LFA_serum) and the blood lateral flow assay (LFA_blood) for the detection of antibodies to Brucella spp. using Bayesian latent class models (BLCMs). Sera and whole blood were collected from naturally infected cattle reared in smallholder, small-scale commercial and large-scale commercial farms in Zimbabwe (n = 1022) and Botswana (n = 770). The BLCMs were fitted under the assumption that conditional dependences existed between the tests. Based on the conditional dependence model, the RBT had the highest Se of 0.897 (95 % Probability Intervals: 0.854; 0.932) compared to 0.827 (0.773; 0.872), 0.812 (0.76; 0.858) and 0.809 (0.785; 0.832) for the LFA_serum, LFA_blood and CFT, respectively. The CFT recorded a higher Sp of 0.999 (0.995; 1.000) than the LFA_serum 0.996 (0.99; 1.000), the LFA_blood 0.984 (0.976; 0.991) and the RBT 0.969 (0.959; 0.978). The data indicated that both the Se and Sp of RBT and CFT and the Sp of LFA_serum and LFA_blood were conditionally independent, while the Se appeared to be conditionally dependent. These results indicated that none of the evaluated tests had perfect Se and Sp and consequently could not be used alone for the diagnosis of brucellosis in cattle from the studied farming sectors. Thus, based on high Se and Sp, respectively, a brucellosis testing regimen using the RBT (screening) and the LFA (confirmatory) may be considered.

Seroprevalence and risk factors of brucellosis in livestock in the wildlife and livestock interface area of Similipal Biosphere Reserve, India

Background and Aim

Brucellosis is an important zoonotic disease that affects fertility in farm animals. The risk factors of brucellosis have not been well studied. This study aimed to understand the seroprevalence and risk factors of brucellosis among livestock in Bangriposi block of Mayurbhanj district in Odisha, a region that borders Similipal wildlife reserve.

Materials and Methods

Rose Bengal plate test (RBPT) was carried out to estimate the seroprevalence of the livestock in this region. Bivariate analysis was carried out to analyze the association between the variables and brucellosis. Binary logistic regression was performed to assess the risk factors associated with brucellosis in the livestock.

Results

Based on RBPT, the seroprevalence of brucellosis among cattle and goats was estimated to be 1.1% and 11.2%, respectively. Binary logistic regression analysis indicates that study area, age, goats, animals with a history of abortion, and rearing practices were the major risk factors in this region.

Conclusion

This is one of the first studies in India to shed light on risk factors of brucellosis, an important neglected disease that affects the health of animals and humans and nation's economy.

Seroepidemiology and the Molecular Detection of Animal Brucellosis in Punjab, Pakistan

Brucellosis is an infectious disease caused by bacteria of the genus Brucella (B.), affecting both animals and humans, causing severe economic loses and severe illness, respectively. The objective of the present study was to determine the seroprevalence and the risk factors associated with caprine, ovine, and bovine brucellosis in selected districts of Punjab, Pakistan. A total of 1083 blood samples were randomly collected from animals (goats = 440, sheep = 203, cows = 206, and buffaloes = 234). Questionnaires were used to collect data on risk factors associated with brucellosis on the sampling day. All samples were initially screened for anti-Brucella antibodies using the rose bengal plate test (RBPT). The seropositive serum samples were confirmed by a quantitative real-time polymerase chain reaction (PCR) assay for the detection of the Brucella genus- and Brucella species-specific DNA (B. abortus and B. melitensis). Univariant and binary logistic regression were used to identify important risk factors of brucellosis. Anti-Brucella antibodies and DNA were detected in 35 (3.23%) serum samples. Thirty-four (97.1%) DNA samples were confirmed as B. melitensis by qRT-PCR. Abortion history and natural mating were found to be potential risk factors. Brucella melitensis was identified as the causative agent of caprine, ovine, and bovine brucellosis in the selected districts of Punjab, Pakistan. Diseased animals may act as a source of infection for other animals. The elimination of positive seroreactors, development of control strategies for brucellosis, and education programs regarding the control of zoonotic disease are highly needed in developing countries like Pakistan.

Prevalence and risk factors for brucellosis seropositivity in cattle in Nyagatare District, Eastern Province, Rwanda

A survey involving 120 small-scale dairy farmers was carried out to assess risk factors associated with brucellosis in cattle from selected sectors of Nyagatare District, Rwanda. A sample of cattle from nine selected sectors of Nyagatare was tested for brucellosis using the Rose Bengal Test. Of the respondents, 57.5% were unaware of brucellosis as a disease, 85.8% did not screen new additions to the herd for brucellosis and 82.5% did not remove brucellosis seropositive animals from the herd. The prevalence of brucellosis in herds with cows with no history of abortion was 38.5% and 17.0% in those with a history of abortion. None of the respondents disinfected abortion sites or vaccinated against brucellosis. The prevalence of brucellosis in cows with a history of retained placenta was 36% and 2% in those with no history of retained placenta. Of the respondents, 62.5% reportedly fed foetal membranes to dogs. About 65.8% of the respondents with brucellosis-positive animals reported a calving interval longer than 1 year. Katabagemu (28.6%) had the highest prevalence of brucellosis seropositivity while Karama had none. Brucellosis in cows (21.4%) was significantly higher than that in heifers (12.8%) (p < 0.05), but there was no significant difference between heifers and bulls or between bulls and cows (p > 0.05). The occurrence of brucellosis in herds with 40-70 cattle (26.9%) was significantly greater than the 14.9% of herds with 10-39 cattle (p < 0.05). Seropositivity to brucellosis in cross-breed cattle (23.6%) was significantly greater than that in indigenous cattle (13.8%) (p < 0.05). There was no significant difference in the overall prevalence of brucellosis in cattle from different grazing systems (p > 0.05). Seropositivity to brucellosis was significantly different (p < 0.05) between the fourth parity (32.5%) and first parity (14.3%) cows. The findings in this study confirmed the existence of brucellosis as a problem in Nyagatare and the authors recommend that farmer education on the epidemiology, risk factors and mitigation of the disease be undertaken as a matter of urgency.

Seroprevalence and risk factors of brucellosis among slaughtered indigenous cattle, abattoir personnel and pregnant women in Ngaoundéré, Cameroon

BACKGROUND

Brucellosis is a neglected debilitating zoonosis with a high prevalence in many developing countries. Bovine brucellosis is widespread in Cameroon but the epidemiological situation of human brucellosis is not known. A cross sectional study was carried to determine the seroprevalence and factors associated with bovine and human Brucellosis among abattoir personnel and pregnant women in Ngaoundéré, Cameroon.

METHODS

Serum sample from 590 abattoir cattle and 816 plausible occupational risk and vulnerable humans to brucellosis (107 abattoir personnel and 709 pregnant women) were collected and screened for anti-brucella antibodies using Rose Bengal Plate Test (RBPT) and ELISA tests. Structured questionnaires were used to collect data on socio-demographics and risk-factors. The differences in proportions between seropositive and seronegative reactors were tested using odds-ratio and χ2tests.

RESULTS

Bovine brucellosis seroprevalence was at 3.40% (n = 590; 3.4% for RBPT, 5.93% for i-ELISA). Human Brucella seroprevalence was at 5.6% among abattoir personnel (n = 107; 5.6% for RBPT, 12.15% for Brucella IgG ELISA) and 0.28% in pregnant women (n = 709; both tests). Breed (P < 0.00001) was associated with increased risk of brucellosis in cattle and the seroprevalence was highest among the Djafoun (OR = 16.67, 95%CI: 4.49-28.85) and Akou (OR = 16.96, 95% CI: 0.10-23.91) cattle compared to the other breeds. There was a moderate positive correlation (R2 = 0.5025) of Brucella IgG concentrations (> 200 U/ml) and clinical data for Brucella IgG ELISA seropositive humans. Several potential factors were associated (P > 0.05) with increased risk of human brucellosis seroprevalence among the abattoir personnel. The abattoir personnel were essentially males; the seropositive respondents were male and did not use protective equipment at work. Handling of foetus and uterine contents (OR = 13.00, 95%CI: 1.51-111.88) was associated with increased risk of human brucellosis.

CONCLUSIONS

Antibrucella antibodies are prevalent in cattle (3.40%), among abattoir personnel (5.60%) and in pregnant women (0.28%) in Ngaoundéré, Cameroon. The study reports the first evidence of human brucellosis in Cameroon and therefore, an indication of a real public health problem. Public awareness campaigns and health education especially among livestock professional and in agropastoral communities should be highlighted to disseminate knowledge, associated risk factors and control measures of brucellosis.

Comparative Seroepidemiological Study of Brucellosis in Sheep under Smallholder Farming and Governmental Breeding Ranches of Central and North East Ethiopia

This cross-sectional study was carried out to investigate the status of brucellosis in sheep management under extensive smallholder farming and intensively in governmental breeding ranches in six districts selected from three administrative zones. Using multistage sampling, serum samples of 2409 sheep from 274 flocks were collected and tested using the Rose Bengal Plate Agglutination Test (RBPT) and positive sera were confirmed using a Complement Fixation Test (CFT). Of all animals tested, 4.98% were RBPT positive, and after confirmation with CFT, the overall animal-level prevalence was found to be 4.89% (CI: 3.24-6.9%). Of the flocks sampled, 61 (22.3%, CI: 18.03-29.17%) had at least one animal positive to both tests. Significantly higher (P < 0.001) individual animal seroprevalence of 5.87% (CI: 3.83-7.31%) was found in sheep under smallholder production than in breeding ranches (1.75%, 95% CI: 1.57-3.05%). However, flock level seroprevalence in breeding ranches was found to be 100% (8/8), while in the smallholder production it was 19.92% (CI: 16.4-25.81%). Significantly highest animal-level seroprevalence of 9.55% (CI: 7.91-12.4%) was observed in north Wollo zone's smallholder farms. From the three studied breeding ranches, highest seroprevalence of 3.57% (CI: 2.84%-5.18%) was found in Sheno Agricultural Research Centre. Significantly higher seroprevalence (P < 0.01) was found in aborted sheep and with history of retained fetal membrane in both production systems. All the sheep flocks in the studied breeding ranches were found to be seropositive; hence, this study suggests strict control measures of ovine brucellosis in the breeding reaches, since they could be a source of infection for the smallholder farms.

Seroprevalence of bovine brucellosis and associated risk factors in Nakasongola district, Uganda

A cross-sectional study was carried out between November 2015 and January 2016 to determine the seroprevalence of Brucella antibodies in cattle raised under communal, fenced farms and tethering systems and the associated factors. Seven hundred twenty-eight bovine sera were collected and tested with rose Bengal test as a screening test and the indirect enzyme-linked immunosorbent assay as a confirmatory test. Animal- and herd-level data were collected and binary logistic regression was used to assess the potential risk factors. True animal- and herd-level prevalence was highest in the fenced farms (4.5% (95%CI, 2.3-6.9) and 19.5% (95%CI, 8.2-32.7) respectively). The risks for natural brucellosis infection were sharing water with wild animals (OR = 0.21, 95%CI, 0.104-0.83), herd size (medium: OR = 0.089, 95%CI 0.017-0.449; large: OR = 0.024, 95%CI 0.003-0.203), fenced farms (OR = 3.7, 95% CI, 1.7-7.9), sex (OR = 0.03, 95%CI, 0.01-0.079), and lactation (OR = 0.013, 95%CI, 0.004-0.049). Changes in rangeland tenure and the shift towards intensive cattle production have influenced brucellosis epidemiology. Future studies should aim at identifying the infecting Brucellae and examining the role of wildlife in brucellosis epidemiology.

Prevalence and risk factors associated with bovine brucellosis in herds under extensive production system in southwestern Nigeria

Using a cross-sectional survey, we determined the prevalence and risk factors associated with bovine brucellosis in herds under extensive production system in southwestern Nigeria. Antibodies to Brucella species in serum samples were tested using the Rose Bengal test (RBT) and competitive enzyme-linked immunosorbent assay (cELISA); for milk, the milk ring test (MRT) and indirect-ELISA (i-ELISA) were used. Questionnaire was administered to cattle herdsmen to determine factors predisposing the animals to bovine brucellosis. Data were analyzed using STATA 12. From 513 serum and 635 milk samples tested among 120 herds, overall animal-level prevalence of 10.1% (95% CI 7.5-12.7%) and 20.2% (95% CI 17.1-23.3%) were recorded by RBT and MRT, respectively; while 9.4% (95% CI 6.9-11.9%) and 17.8% (95% CI 14.8-20.8%) were obtained using cELISA and i-ELISA, respectively. In all, from the 120 herds tested, 29.2% and 43.3% were positive by RBT and MRT, respectively. Multivariable logistic regression revealed that herd location (OR = 8.12, 95% CI 1.68-38.90) and improper disposal of placenta/fetus (OR = 17.33, 95% CI 4.81-62.33) were predictors for a seropositive herd using RBT; while herd location (OR = 5.13, 95% CI 1.27-20.28), large herd size (OR = 2.62, 95% CI 1.15-5.85), and occurrence of abortion for a year or more (OR = 4.62, 95% CI 1.53-13.71) were predictors of seropositivity to antibodies to Brucella spp. using MRT. We found high prevalence of brucellosis in cattle herds under extensive management system in southwestern Nigeria. Urgent and coordinated control strategies are required to mitigate this problem.

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 and Associated Risk Factors of Brucellosis among Indigenous Cattle in the Adamawa and North Regions of Cameroon

A cross-sectional seroprevalence study was conducted on cattle in the North and Adamawa Regions of Cameroon to investigate the status of bovine brucellosis and identify potential risk factors. The diagnosis was carried out using the Rose Bengal Plate test (RBPT) and indirect ELISA (i-ELISA), while questionnaires were used to evaluate risk factors for bovine brucellosis in cattle. The Bayesian approach was used to evaluate the diagnostic tests' sensitivity and specificity. The overall individual level (n = 1031) and herd level (n = 82) seroprevalence were 5.4% (0.4-10.5) and 25.6% (16.2-35.0), respectively. Bayesian analysis revealed sensitivity of 58.3% (26.4-92.7) and 89.6% (80.4-99.4) and specificity of 92.1% (88.7-95.2) and 95.7% (91.1-99.7) for RBPT and i-ELISA, respectively. Management related factors such as region, locality, herd size, and knowledge of brucellosis and animal related factors such as sex and age were significantly associated with seropositivity of brucellosis. Zoonotic brucellosis is a neglected disease in Cameroon. The study highlights the need for control measures and the need to raise public awareness of the zoonotic occurrence and transmission of bovine brucellosis in the country. An integrated disease control strategy mimicking the one health approach involving medical personnel, veterinarians, related stakeholders, and affected communities cannot be overemphasized.

Ocorrência de brucelose e tuberculose bovinas no Rio Grande do Sul com base em dados secundários

RESUMO: Avaliaram-se os resultados de testes para diagnóstico da brucelose e tuberculose bovinas objetivando analisar a distribuição de positividade e características de performance do programa de controle. A análise utilizou como dados secundários todos os resultados de testes para diagnóstico realizados em bovinos no ano de 2008 no estado do Rio Grande do Sul (RS) por médicos veterinários habilitados para atuação no âmbito do Programa Nacional de Controle e Erradicação de Brucelose e Tuberculose Animal. Os dados foram estatisticamente ajustados para minimizar os efeitos de valores extremos e de dados faltantes. Os testes alcançaram 66,80% dos 497 municípios do RS e incluíram a participação de 165 médicos veterinários habilitados. 40,21% dos testes foram realizados nos meses de abril, setembro e outubro, sendo que em 73,90% dos estabelecimentos foram realizados testes para ambas as enfermidades. No caso da brucelose verificou-se que foram testados 35.289 animais, com uma frequência de positivos de 0,25%, enquanto a frequência de estabelecimentos positivos entre os 3.406 testados foi 0,94%. Fêmeas apresentaram frequência de positividade mais elevada (0,29%, de 26.724 testadas) do que machos (0,13%, de 5.235 testados). Animais entre 48-60 meses de idade apresentaram chance de positividade superior às demais faixas etárias (Razão de Chances (RC) =2,63; IC 95%=1,63-4,26). Animais de aptidão leiteira representaram 62,66% dos animais testados, e apresentaram maior chance de positividade do que animais de corte (RC=2,32; IC 95%=1,38-3,90). Adicionalmente, 73,74% dos estabelecimentos testados eram dedicados à produção de leite. Já no caso da tuberculose foram testados 62.149 animais distribuídos em 5.151 propriedades, com frequência de positivos de 0,87% e 3,13%, respectivamente. A chance de positividade aumentou com a idade, sendo que animais com idade acima de 48 meses de idades apresentaram valores superiores aqueles verificados em animais mais jovens (RC=2,07; IC 95%=1,73-2,48). 59,74% dos animais testados eram de aptidão leiteira, os quais apresentaram mais chance de serem positivos do que aqueles de corte (RC=5,03; IC 95%=4,09-6,94). Propriedades leiteiras representaram 78,50% da totalidade dos testes para tuberculose. A análise comparativa do presente trabalho com estudos precedentes de prevalência da brucelose sugere que as ações de controle em curso têm sido efetivas na redução da prevalência da enfermidade no RS. Por outro lado, as informações obtidas no âmbito da tuberculose podem ser indicadoras da condição desta enfermidade, especialmente pela inexistência de estudos de prevalência realizados há menos de 30 anos. Adicionalmente, conclui-se que a utilização de dados secundários, desde que devidamente ajustados, pode ser uma ferramenta eficaz na gestão de programas de saúde animal e em sistemas de monitoramento e vigilância.

Serological prevalence and public health significance of brucellosis on a dairy farm in Namibia from 2011 to 2014

OBJECTIVE

The main objective of this study was to determine the serological prevalence of brucellosis on a dairy farm with no past history of abortions, but where Brucella control measures including test and slaughter and vaccination of heifers at 4-8 months of age was practiced. Secondary data from 2011 to 2014 obtained from the Epidemiology Section of the Directorate of Veterinary Services was used.

RESULTS

Mandatory annual brucellosis testing results for mature dairy cows on a dairy farm for the period 2011-2014 were collated and analyzed. Results of a total of 6912 cows were analysed. The data comprised of the year of testing, number of cows tested for Brucella antibodies and the number of cows that tested positive. Serological testing was carried out using the Rose Bengal Test (RBT) as a screening test and the Complement Fixation Test as a confirmatory test for results that tested positive on the RBPT. Over the 4-year period, one dairy cow tested positive for Brucella antibodies in 2013 giving an apparent prevalence of 0.05% and an overall prevalence of 0.01%. When apparent prevalence was adjusted for RBPT test specificity and sensitivity of 71 and 78% respectively, true prevalence was determined to be zero.

Prevalence of bovine brucellosis in slaughtered cattle and barriers to better protection of abattoir workers in Ibadan, South-Western Nigeria

INTRODUCTION

Brucellosis is a neglected zoonosis of public health importance. This study was conducted to determine the prevalence and risk factors of brucellosis among slaughtered cattle as well as challenges to the protection of abattoir workers in Nigeria.

METHODS

A slaughterhouse study was conducted in a major abattoir in Ibadan from March to August, 2013. To diagnose brucellosis, serum samples from 1,241 slaughtered cattle were tested using Rose-Bengal test (RBT) and competitive enzyme-linked immunosorbent assay (cELISA); again, 57 milk samples were tested with milk ring test (MRT) and indirect ELISA (iELISA). Furthermore, a survey on the usage of personal protective equipment (PPE) and challenges to its use by abattoir workers was done. Data were analysed using Stata 12.

RESULTS

Seroprevalence by RBT was 7.8%; 77.3% (75/97) of these were corroborated by cELISA. Prevalence in milk samples by MRT and indirect ELISA were 33.3% and 3.5%, respectively. Sex (OR: 2.5; 95%CI:1.3-4.5) was the factor significantly associated with Brucella seropositivity. None of the abattoir workers used standard protective overalls; while, 99.6% of the meat handlers and 84.1% of the butchers worked barefoot. Most of the workers (75.7%) wore no protective gloves. The respondents agreed that provision of free PPE and sanctions against non-users would encourage its use.

CONCLUSION

Our findings indicate moderate prevalence (7.8%) of bovine brucellosis with sex of cattle being a risk factor. A notable barrier to better protection of abattoir workers against brucellosis is perceived inconvenience arising from use of gloves. Therefore, preventive and control measures against brucellosis must include education and use of PPE among abattoir workers.

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.

Brucellosis in Sub-Saharan Africa: Current challenges for management, diagnosis and control

Brucellosis is a highly contagious zoonosis caused by bacteria of the genus Brucella and affecting domestic and wild mammals. In this paper, the bacteriological and serological evidence of brucellosis in Sub-Saharan Africa (SSA) and its epidemiological characteristics are discussed. The tools available for the diagnosis and treatment of human brucellosis and for the diagnosis and control of animal brucellosis and their applicability in the context of SSA are presented and gaps identified. These gaps concern mostly the need for simpler and more affordable antimicrobial treatments against human brucellosis, the development of a B. melitensis vaccine that could circumvent the drawbacks of the currently available Rev 1 vaccine, and the investigation of serological diagnostic tests for camel brucellosis and wildlife. Strategies for the implementation of animal vaccination are also discussed.

Sero-epidemiological survey and risk factors associated with bovine brucellosis among slaughtered cattle in Nigeria

Bovine brucellosis is endemic in Nigeria; however, limited data exist on nationwide studies and risk factors associated with the disease. Using a cross-sectional sero-epidemiological survey, we determined the prevalence of and risk factors for brucellosis in slaughtered cattle in three geographical regions of Nigeria. Serum samples from randomly selected unvaccinated cattle slaughtered over a period of 3 years (between December 2010 and September 2013) from northern, southern and south-western Nigeria were tested for antibodies to Brucella abortus using the Rose Bengal test. Data associated with risk factors of brucellosis were analysed by Stata Version 12. In all, 8105 cattle were screened. An overall seroprevalence of 3.9% (315/8105) was recorded by the Rose Bengal test, with 3.8%, 3.4% and 4.0% from the northern, southern and south-western regions, respectively. Bivariate analysis showed that cattle screened in northern Nigeria were less likely to be seropositive for antibodies to Brucella spp. than those from south-western Nigeria (odds ratio = 0.94; 95% confidence interval: 0.73–1.22). However, logistic regression analysis revealed that breed ( p = 0.04) and sex ( p £ 0.0001) of cattle were statistically significant for seropositivity to Brucella spp. The study found that brucellosis was endemic at a low prevalence among slaughtered cattle in Nigeria, with sex and breed of cattle being significant risk factors. Considering the public health implications of brucellosis, we advocate coordinated surveillance for the disease among diverse cattle populations in Nigeria, as is carried out in most developed countries.

Epidemiological study of bovine brucellosis in three senatorial zones of Bauchi State, Nigeria

Aim:

To determine the seroepidemiological patterns of bovine brucellosis in three senatorial zones of Bauchi State, Nigeria.

Materials and Methods:

Blood samples were aseptically collected from the anterior jugular vein of 336 slaughtered cattle, between September 2013 and March 2014 in three senatorial zones of Bauchi State, Nigeria. The sera obtained were screened for brucellosis using rose Bengal plate test (RBPT) and serum agglutination test (SAT) in parallel. The data generated was subjected to Chi-square and Fishers exact test analysis to establish whether there is a relationship between the breeds, sex, and location of the animals sampled.

Results:

Of the 336 cattle screened, 18 (5.4%) and 13 (3.9%) were positive by RBPT and SAT, respectively. There was no statistically significant association (p>0.05) between the sex, age, and location of cattle with seropositivity of brucellosis in the state. It was concluded that brucellosis is prevalent in Bauchi State. Further study is recommended in other abattoirs and herds of cattle in Bauchi State for confirmation of the status of the disease among cattle slaughtered in the state.

Conclusion:

A high seroprevalence of brucellosis among the cattle in Bauchi state indicates that the disease is endemic and cattle are one of the animals that perpetuate and sustain the disease.

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.

Seroprevalence and risk factors for brucellosis in cattle in selected districts of Jimma zone, Ethiopia

A cross-sectional study was carried out in Jimma town and Chora Botor district of Jimma zone from February 2014 to May 2014 to determine seroprevalence and risk factors of brucellosis in cattle. A total of 348 blood samples (174 each from zebu and crossbreed) were collected. The sera were separated and screened by Rose Bengal plate test (RBPT), and positive sera were retested by complement fixation test (CFT) for confirmation. The overall seroprevalence of bovine brucellosis was 1.4 and 0.3 % as tested by RBPT and CFT, respectively. The seroprevalence of bovine brucellosis in indigenous and crossbreed cattle was 1.1 and 0.6 % and 1.7 and 0 % using RBPT and CFT, respectively. Retained fetal membrane was the only risk factor found to be significantly associated with seropositivity of brucellosis in this study (p = 0.019). The overall seroprevalence of brucellosis was very low. However, due to the zoonotic and economic importance of the disease, prevention and control measures are required to stop further spread of the disease. To effectively implement this, the One Health (OH) is the most constructive approach we recommend.

Meta-analysis of Brucella seroprevalence in dairy cattle of Ethiopia

This meta-analysis estimates a single-group summary (effect size) for seroprevalence of Brucella spp. exposure in dairy cattle of Ethiopia. It also attempts to identify study-level variables that could explain the variation in apparent seroprevalence. The literature search was restricted to studies published in English language from January 2000 to December 2013. A template was designed to retrieve the most biologically plausible and consistent variables from the articles. A total of 29 published papers containing 40 animal-level studies were used in the analyses. The single-group summary of Brucella seroprevalence in cattle was estimated to reach 3.3 % with 95 % confidence interval (CI) (2.6-4.2 %). Of all the variables considered, region was the only specific factor identified to explain about 20 % of between-study variation. Accordingly, the region-based meta-analysis forest plot revealed the highest prevalence in central Ethiopia followed by southern part. The lowest prevalence estimate was observed in the western part of the country. The visual inspection of the funnel plot demonstrated the presence of possible publication bias which might dictate shortage of studies with higher prevalences or variance inflation due to infectiousness of Brucella. In conclusion, the quantitative review showed the seroprevalence to be low but widely distributed. More importantly, the review underscores the need for isolation and characterization of the circulating Brucella spp. to capture the type of Brucella spp. involved and its distribution in cattle in Ethiopia.

Seropositivity and risk factors for Brucella in dairy cows in urban and peri-urban small-scale farming in Tajikistan

In this cross-sectional study, we assessed and mapped the seroprevalence of brucellosis in small-scale dairy farming in an urban and peri-urban area of Tajikistan and investigated factors associated with seropositivity. As urban and peri-urban farming is both an opportunity to improve the livelihood for small-scale farmers and a potential public health hazard, studies are warranted to reveal possible peculiarities in the epidemiology of brucellosis in this type of dairy farming. In total, 904 cows of breeding age belonging to 443 herds in 32 villages were serologically tested with indirect enzyme-linked immunosorbent assay (ELISA) and positive samples confirmed with competitive ELISA. Two logistic regression models were used to investigate an association between seropositivity and risk factors at herd and individual level. The herd and individual seroprevalences were 4.1 and 2.0 %, respectively. Herds with a history of abortions were found to be associated with seropositivity [odds ratio (OR) = 5.3; 95 % confidence interval (CI), 1.3–21.3]. Large herds with more than eight cattle were more likely to be seropositive compared to smaller herds with one to two cattle (OR = 13.9; 95 % CI, 1.6–119). The number of calves produced per cow (indicating age) was found to be associated with seropositivity. Younger cows with one to two produced calves were less likely to be seropositive compared to older cows with more than six produced calves (OR = 0.24; 95 % CI, 0.06–1.0). Neither introduction of new cattle to the herd nor communal grazing was associated with seropositivity. This study shows that infection with Brucella (1) is present in small-scale urban and peri-urban dairy farming in Tajikistan and (2) has significant negative effects on reproductive performance in this farming system and (3) that some previously known risk factors for seropositivity in rural farming system were absent here.

Brucellosis seroprevalence in Bali cattle with reproductive failure in South Sulawesi and Brucella abortus biovar 1 genotypes in the Eastern Indonesian archipelago

Background

Brucellosis is a major cause of infertility and reproductive failure in livestock. While cattle in the Eastern Indonesian archipelago suffers from reproductive problems information on bovine brucellosis in the region is fragmentary. The control of brucellosis requires a major and prolonged effort and confirmation of the infection by isolation with detailed knowledge of the spread of the infection is essential when planning a control program.

Results

Serological investigation of Brucella infection in beef cattle tended under extensive farming conditions revealed a high seroprevalence (19.3%; 95% CI, 17–22) in the compliment fixation tests. The results of a rapid and simple field test correlated well with the Rose Bengal test (kappa, 0.917) and indicated an acceptable sensitivity (87.5%) and specificity (98.1%) compared with the complement fixation test. Reproductive failure was reported for 39.0% of the cows with a loss of calves due to abortion or early death amounting to 19.3%. Past reproductive failure did not, however, correlate with seropositivity in the complement fixation test (RP = 1.21; P = 0.847). B. abortus biovar 1 was freshly isolated from the hygromas of two cows and together with thirty banked isolates collected since 1990 from different parts of Sulawesi and Timor eight related genotypes could be distinguished with one genotype being identical to that of an isolate (BfR91) from Switzerland. The Indonesian genotypes formed together with BfR91 and one African and one North American isolate a distinct branch on the B. abortus biovar 1 dendogram.

Conclusions

Bovine brucellosis appears to be widespread in the Eastern Indonesian archipelago and calls for urgent intervention. The fresh isolation of the pathogen together with the observed high seroprevalence demonstrates the presence and frequent exposure of cattle in the area to the pathogen. The application of a rapid and simple field test for brucellosis could be very useful for the quick screening of cattle at the pen side.

Milk yield and reproductive performance of brucellosis-vaccinated but seropositive Holstein cows

The aim of this research was to study if seropositivity for brucellosis in vaccinated cows against this disease hampers reproductive performance and milk production in high-yielding Holstein cows. For this purpose 1,026 healthy cows and 372 cows seropositive for brucellosis were enrolled in this study. Cows positive to card test and subsequently to the rivanol test were further subjected to the radial immunodiffusion (RID) test. It was found that only 11% of the presumably infected cows by brucellosis screening tests were really infected with this disease. The reproductive performance of the group of cows with 11% Brucella-infected animals was not impaired; overall pregnancy rate did not differ between seropositive and healthy cows (30.9 vs. 29.6%). The abortion rates were similar between seropositive cows (5.3%) and seronegative animals (6.9%). Cows in the herd with 11% Brucella-infected animals produced significantly more milk than unaffected cows over a 305-day lactation (10,684 ± 1,720 vs. 10,345 ± 1,736; mean ± SD; P < 0.05). It was concluded that in dairy herds vaccinated against brucellosis with both 19 and RB51 strains, supplemental tests such as RID need to be conducted on all reactors in order to maintain diagnostic accuracy. These results also indicate that 11% animal prevalence of brucellosis did not exert a detrimental effect on 305-day milk yield and reproductive performance in high milk-yielding Holstein cows.

The status of bovine brucellosis in Ethiopia with special emphasis on exotic and cross bred cattle in dairy and breeding farms

A cross-sectional study was conducted to investigate the seroprevalence of brucellosis and identify risk factors in exotic and cross bred cattle in Ethiopia. A total of 2334 cattle from 273 farms were tested serially for Brucella antibodies using the Rose Bengal Plate Test (RBPT) and the Compliment Fixation Test (CFT). The overall animal level seroprevalence was 1.9% (95% CI: 1.2, 2.6), with urban and peri-urban dairy 2.4% (95% CI: 1.4, 3.4), commercial 1.5% (95% CI: 0.5, 2.5) and breeding farms 1.5% (95% CI: 0.2, 3.2). The overall farm level prevalence was 10.6% (95% CI: 6.9, 14.3), with 8.6% (95% CI: 4.8, 12.4) in urban and peri-urban dairy followed by 16.9% (95% CI: 7.3, 26.6) in commercial and 20.0% (95% CI: 0.0, 59.4) in breeding farms. At individual animal level, purchased cows and adult age groups were observed to associate with Brucella seropositivity while presence of small ruminants on the farm was the only factor associated with increased risk of herd level Brucella infection. The lack of association between reproductive disorders and Brucella seroprevalence suggest that other causes largely outweigh as causes of the aforesaid disorder in studied production systems and demands an investigation. Finally, the need for isolation and characterization of circulating Brucella spp. and institution of regulatory measures to reinforce farm biosecurity was suggested.