Herd and individual animal prevalence of bovine brucellosis with associated risk factors on dairy farms in Haryana and Punjab in India

The Reasons Behind Long-Term Endemicity of Brucellosis in Low and Middle-Income Countries: Challenges and Future Perspectives

Brucellosis is a neglected worldwide zoonotic disease with more than 500,000 new human cases each year. Direct contact with infected animals and consumption of undercooked animal origin foods are the main routes of brucellosis transmission to humans. Although long endeavor has been applied to control and eliminate brucellosis from animal and human populations in developing countries especially in low- and middle-income countries (LMICs), the disease is still endemic in these regions. Many common or unique factors including raw milk consumption, unhygienic slaughter of livestock, extensive husbandry, budgetary limitations, misdiagnosis, and other conditions play a role in long-term endemicity of brucellosis in these locations. It has been shown that One Health is the only practical approach to control brucellosis; however, applying such methods is challenging in low-resource areas. In such conditions, brucellosis is continuously maintained in animals and repeatedly spread to human populations. In this article, factors playing a critical role in brucellosis endemicity, and the real conditions challenging the application of One Health approach in control of brucellosis are highlighted.

Seroprevalence and Risk Factors Related to Bovine Brucellosis in Continental Ecuador

Bovine brucellosis is a worldwide zoonotic contagious disease. According to World Animal Health Information System reports Ecuador has presented an increasing number of bovine brucellosis outbreaks in the continental territory over the past years (756 in 2018 versus 964 in 2021), generating economic losses for producers and causing a risk to public health. A cross-sectional study was conducted to investigate the seroprevalence of bovine brucellosis and associated risk or protective factors between May and June 2018. This stratified random study was implemented in 290 cattle herds located in the 23 provinces of continental Ecuador, which represents a total of 3737 cows aged 24 months or older. A competitive ELISA was used to detect Brucella antibodies. Simultaneously, an epidemiological survey was implemented to assess the brucellosis risk or protective factors. The apparent prevalence of bovine brucellosis at the herd level was 21.3% (95% CI: 16.8-26.6) and 6.2% (95% CI: 5.5-7) at the animal level. Univariate and multivariate logistic regression analyses were performed to determine the relationship between the potential factors associated with the presence of bovine brucellosis. The risk factors identified after multivariate analysis were a surface in ha per herd > 70 ha (OR = 2.73; 95% CI: 1.18-6.32) and the number of parturitions per animal (two or more with OR ≥ 1.8 and p-value ≤ 0.047). On the contrary, the protective factors were the region (farms located in the eastern region) and the absence of reported clinical signs. In addition, in herds where extensive production predominates, farmers have a low level of knowledge, and the farm biosecurity level is low. These results can guide the authorities in managing the risk factors identified, understanding the current epidemiological situation in Ecuador, improving the bovine brucellosis control program and food safety, as well as increase the one-health approach.

Management of bovine brucellosis in organized dairy herds through the identification of risk factors: A cross-sectional study from Karnataka, India

Background and Aim

Brucellosis is an infectious disease caused by Brucella species. This study aimed to identify the risk factors associated with bovine brucellosis seropositivity in organized dairy farms to control the disease in unvaccinated adult bovine herds in Karnataka, India.

Materials and Methods

In total, 3610 samples (3221 cattle and 389 buffaloes) were subjected to parallel testing using the Rose Bengal plate test and protein G-based enzyme-linked immunosorbent assay, followed by analyses of animal- and farm-level epidemiological datasets to identify the risk factors.

Results

The apparent brucellosis prevalence at the animal level was higher in buffaloes (8.2%, 95% confidence interval [CI] = 5.9-11.4) than in cattle (6.1%, 95% CI = 5.3-7.0). In a multivariable logistic model, animals calved 3-5 times (odds ratio [OR] = 2.22, 95% CI = 1.50-3.1, reference [ref]: animals calved <2 times); animals with a history of abortion (OR = 54.73, 95% CI = 33.66-89.02), repeat breeding (OR = 19.46, 95% CI = 11.72-32.25), and placental retention (OR = 13.94, 95% CI = 4.92-39.42, ref: no clinical signs); and dogs on farms (OR = 2.55, 95% CI = 1.48-4.40, ref: absence of dogs); disposal of aborted fetus in open fields (OR = 4.97, 95% CI = 1.93-12.84) and water bodies (OR = 2.22, 95% CI = 1.50-3.1, ref: buried); purchase of animals from other farms (OR = 6.46, 95% CI = 1.01-41.67, ref: government farms); hand milking (OR = 1.98, 95% CI = 1.02-10.0, ref: machine milking); and use of monthly veterinary services (OR = 3.45, 95% CI = 1.28-9.29, ref: weekly services) were considered significant risk factors for brucellosis in organized bovine herds (p < 0.01).

Conclusion

The study identified that the animals calved 3-5 times or with a history of abortion/repeat breeding/placental retention, and disposal of aborted fetus in open fields/water bodies as the potential risk factors for bovine brucellosis. These risk factors should be controlled through the implementation of best practices to reduce the brucellosis burden in bovine farms.

Prevalence of brucellosis in livestock keepers and domestic ruminants in Baringo County, Kenya

Brucellosis is widely distributed in more than 170 countries around the world, where it poses a huge threat to animal husbandry and human health. Brucellosis is a worldwide re-emerging zoonotic disease that poses serious public health problems in many developing countries including Kenya. However, prevalence of brucellosis has not been determined in Baringo County, Kenya, yet there is a continuous movement of cattle resulting from trade and grazing, thus predisposing many herds to brucellosis infection. We investigated the sero-prevalence of brucellosis in humans and domestic ruminants: sheep, goats, cattle and camels among livestock keeping communities in Baringo County, Kenya. In addition, we analyzed the seropositive samples for molecular detection of Brucella species. The study adopted a cross-sectional survey using quantitative data collection methods. The diagnosis was carried out using a competitive enzyme-linked immunosorbent assay (c-ELISA) and the real-time PCR assays. The sero-prevalence of brucellosis among human blood samples was 0.6% (n = 4/640) in Baringo County. About 22.30% (n = 143/640) of animal blood samples examined tested positive for Brucella genus-specific ELISA test. Cattle had a high prevalence of 22.88% (n = 93/322) followed by camels 20.00% (n = 21/105), goats 15.48% (n = 24/155) and subsequently sheep at 8.62% (n = 5/58). Overall, 7.5% (n = 6/80) of the seropositive samples amplified with the genus-specific primers. Brucella melitensis was detected in one out of the six genus positive samples, while none amplified with the B. abortus target. Even though there was high prevalence of brucellosis among livestock in Baringo County, the highest prevalence was invariably noted in cattle, followed by camels, goats and sheep, respectively. Livestock keepers had low prevalence of brucellosis. This implies that there was low risk of transmission of brucellosis between livestock keepers and their livestock.

Epidemiology of bovine brucellosis in Hisar, India: identification of risk factors and assessment of knowledge, attitudes, and practices among livestock owners

Brucellosis caused by facultative intracellular bacteria, Brucella, remains a global threat to both animal and human health. In this study we aimed to identify potential risk factors of bovine brucellosis and to assess the knowledge, attitudes, and practices (KAPs) of livestock keepers in Hisar, India. A standardized questionnaire was used to collate information regarding potential risk factors of bovine brucellosis and livestock owners' KAPs. A total of 127 livestock keepers were involved. Serum samples from their animals (n = 635) were tested for the presence of antibodies against Brucella by Rose Bengal Plate Test (RBPT) and indirect enzyme-linked immunosorbent assay (iELISA). Out of these, 78 (61.4%) of the herds had at least one seropositive animal, and 302 (47.6%) of the cattle were seropositive. Univariate and multivariate analysis revealed significant associations between intensive farm type (OR = 4.6; 95% CI, 1.6-16.7; P = 0.009), hygienic disposal of aborted fetuses (OR = 0.3; 95% CI, 0.08-0.9; P = 0.04) and herd seropositivity for brucellosis. The majority, 96 (75.6%) of the respondents, were males aged 18-50, and 82 (64.6%) owned a small-backyard farm. Only 51 (40.2%) of the participants knew about brucellosis; out of them, 54.9% (28/51) could not identify clinical signs of brucellosis. Six (11.8%) participants indicated abortion as the most noticeable clinical sign, and 45.1% indicated that consumption of raw milk is associated with high risk of contracting brucellosis. A large proportion of respondents confirmed that milk from their animals was regularly consumed (86.6%) and sold (59.8%) to other people. These results suggest that bovine brucellosis is endemic in Haryana, where Brucella-contaminated milk is likely being regularly sold. Brucellosis control efforts in Haryana should include education programs to raise awareness of the disease and means to control it in cattle and to prevent zoonotic transmission.

Epidemiology of brucellosis in cattle and dairy farmers of rural Ludhiana, Punjab

Brucellosis is a zoonotic disease imposing significant impacts on livestock production and public health worldwide. India is the world's leading milk producer and Punjab is the state which produces the most cattle and buffalo milk per capita. The aim of this study was to investigate the epidemiology of bovine brucellosis to provide evidence for control of the disease in Punjab State, India. A cross-sectional study of dairy farms was conducted in humans and livestock in rural Ludhiana district using a multi-stage sampling strategy. The study suggests that brucellosis is endemic at high levels in cattle and buffalo in the study area with 15.1% of large ruminants testing seropositive and approximately a third of dairy farms having at least one animal test seropositive. In total, 9.7% of those in direct contact with livestock tested seropositive for Brucella spp. Persons that assisted with calving and/or abortion within the last year on a farm with seronegative livestock and people which did not assist with calving/abortion had 0.35 (95% CI: 0.17 to 7.1) and 0.21 (0.09 to 0.46) times the odds of testing seropositive compared to persons assisting with calving/abortion in a seropositive farm, respectively. The study demonstrated that persons in direct contact with cattle and buffalo in the study area have high risk of exposure to Brucella spp. Control of the disease in livestock is likely to result in benefits to both animal and public health sectors.

The feasibility and acceptability of various bovine brucellosis control strategies in India

Bovine brucellosis is a neglected zoonotic disease prevalent in several developing countries including India. It has been successfully controlled in many developed countries by using vaccination in conjunction with extensive surveillance and test-and-cull approaches, but some of these approaches do not suit Indian culture and norms. This study was conducted to investigate the feasibility and social acceptability of various bovine brucellosis control strategies in India. Focus group discussions and key-informant interviews were conducted with veterinarians, para-veterinarians, veterinary academics, farmers and other stakeholders. Vaccination with the Brucella strain 19 vaccine was considered feasible, but the participants were concerned about the risk of self-inoculation, the inability to vaccinate pregnant and male animals, the difficulty to differentiate vaccinated from diseased animals and the challenges of maintaining the vaccine cold chain in India. As expected, the test-and-cull approach was not considered feasible as cattle are considered sacred by Hindus and their slaughter is banned in most states. Although the test-and-segregation approach appears reasonable in theory, it would have low acceptability, if implemented without providing any compensation to farmers. Negligible biosecurity was implemented by farmers: almost no biosecurity procedures were performed for visitors entering a farm, and testing of animals was rarely undertaken before introducing them to a farm. However, the participants considered that improving biosecurity would be more acceptable and feasible than both the test-and-cull and the test-and-segregation approaches. Similarly, inadequate personal protection was used by veterinary personnel for handling parturition, retention of placenta and abortion cases; this was considered as another area of possible improvement. Farmers and veterinarians expressed serious concerns about stray cattle as many of them could potentially be infected with brucellosis, and thus could spread the infection between farms. This study recommends using vaccination and biosecurity along with some ancillary strategies to control brucellosis in India. Information from the study could be used to develop an evidence-based disease control program for the disease in the country.

Serological evidence of Brucellosis in selected gaushalas of Haryana

Brucellosis is a neglected zoonotic disease with significant economic and public health consequences to human and animal population in developing countries. The objective of the present study was to determine the serological evidences of brucellosis in cattle reared in two gaushalas of Hisar and Jind districts, Haryana. The serological tests: Rose Bengal Plate Test (RBPT), Serum Agglutination Test (SAT) and Enzyme Linked Immunosorbent Assay (ELISA) were employed for screening the animals for brucellosis. The overall seropositivity by RBPT, SAT and ELISA was 23.46%, 20.67% and 28.49% respectively. The logistic regression modalities concluded higher likelihood of brucellosis with age > 6 years followed by 3–6 year than cows with <3 years. The agreement between tests (RBPT and ELISA, SAT and ELISA and RBPT and SAT) was found to be 0.87 (95% CI: 0.857–0.882), 0.70 (95% CI: 0.684–0.718) and 0.82 (95% CI: 0.809–0.834) respectively by kappa statistic. This study concluded high infection rate in gaushala where animals were kept as closed population with more risks of brucellosis among older milching animals which poses potential public health risk through consumption of unpasteurized milk.

Spatial sero-prevalence of brucellosis in small ruminants of India: Nationwide cross-sectional study for the year 2017-2018

Brucellosis in small ruminants caused mainly due to Brucella melitensis is an important zoonotic disease characterized by abortion, retained placenta, infertility, orchitis, epididymitis and rarely arthritis. Small ruminants are the main source of economy for the rural and marginally poor farmers and brucellosis is resulting in huge economic losses due to abortions and infertility and causing public health concern among the small ruminant keepers. Bovine brucellosis control programme has been implemented in India and small ruminants are left out of the programme mainly due to paucity of brucellosis status. The present cross-sectional study based on stratified random sampling was undertaken during 2017-18 to provide the nationwide brucellosis sero-prevalence in small ruminants. A total of 24,056 small ruminant serum samples (sheep samples = 8,103 [male-2,440 and female-5,663] and goat samples = 15,953 [male-4,331 and female-11,622]) sourced from 27 out of 29 states and two out of seven union territories (UTs), 350 districts of total 640 districts (54.68% of the Indian districts) and from 1,462 villages out of 6,40,867 villages (43.83% of the Indian villages). The serum samples were tested by indirect ELISA and overall brucellosis apparent and true prevalence of 7.45 (95% CI: 7.13-7.79) and 3.79 (95% CI: 3.44-4.17) was recorded. Significantly higher brucellosis sero-prevalence (p < .0001) was observed in sheep (11.55%) than goats (5.37%). Similarly, brucellosis seropositivity was highly significant in females compared to males in both sheep and goats. Countrywide, greater than 5% brucellosis sero-prevalence in sheep and goats was recorded in 14 and 10 states, respectively, indicating endemicity of the disease. The study provided the latest update on nationwide spatial sero-prevalence of small ruminant brucellosis which will aid government to strengthen regular surveillance and vaccination to reduce the disease burden and public health problems in the country.

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.

Seroepidemiological survey of brucellosis and isolation of Brucella suis from swine herds of Meghalaya, North-East India

Brucellosis is a well-known and wide spread zoonotic disease. It is endemic in several parts of Asia, including India. In this study, seroprevalence of porcine brucellosis was studied among apparently healthy pigs in Meghalaya where pig keeping plays a significant function in socio-economic development. Serum samples (3,597) from pigs were screened using Rose Bengal Plate Test (RBPT) and indirect ELISA. Isolation of Brucella was attempted in clinical samples. A total of 13 (0.36%) were positive by RBPT and 72(2%) by Indirect ELISA. Brucella suis isolate was recovered from placenta of an aborted pig. Risk factors involved in the transmission of brucellosis amongst swine herd were studied. It was observed that age (OR=0.590; P=0.04) and sex (OR=0.557; P=0.04) were significant intrinsic risk factors for transmission of porcine brucellosis. Although the seroprevalence is low, isolation of B. suis from an aborted pig indicated that disease is actively circulating among swine herds of Meghalaya.

Multilocus variable number tandem repeat analysis (MLVA)-typing of Brucella abortus isolates of India reveals limited genetic diversity

Multilocus variable number tandem repeat analysis (MLVA) technique has wide applications in studying phylogenies and short-term epidemiology of pathogens. The technique has been extensively used worldwide in molecular epidemiology of Brucella genus. Only one study on this aspect is reported from India despite its economic and public health significance in country. The present study isolated B. abortus from domesticated bovines of Jammu region of Jammu and Kashmir state, India, and applied MLVA for 16 loci (MLVA-16). MLVA results were compared with the results of a previous study and with MLVA data of Indian isolates present in http://microbesgenotyping.i2bc.paris-saclay.fr/database. In the study, 136 samples from bovines (cattle and buffaloes) of 47 farms of Jammu region were processed for isolation. Eleven isolates of B. abortus biovar 1 from 6 farms were obtained. In MLVA-16 analysis, although the isolates were classified in a single cluster, 5 genotypes were obtained with a specific genotype being prevalent on each farm. The study identifies that MLVA-16 is capable to differentiate B. abortus strains in an area having high genetic similarity among isolates. On comparing the results with previous study and database, the isolates were found to have high genetic similarity indicating that the genetic diversity of B. abortus in India is very limited. It probably indicates that India is contaminated recently with B. abortus. To test this hypothesis, analysis of whole genome sequencing data of diverse collection of Indian B. abortus strains is required.

Brucellosis in India: results of a collaborative workshop to define One Health priorities

Brucellosis is an important zoonosis worldwide. In livestock, it frequently causes chronic disease with reproductive failures that contribute to production losses, and in humans, it causes an often-chronic febrile illness that is frequently underdiagnosed in many low- and middle-income countries, including India. India has one of the largest ruminant populations in the world, and brucellosis is endemic in the country in both humans and animals. In November 2017, the International Livestock Research Institute invited experts from government, national research institutes, universities, and different international organizations to a one-day meeting to set priorities towards a "One Health" control strategy for brucellosis in India. Using a risk prioritization exercise followed by discussions, the meeting agreed on the following priorities: collaboration (transboundary and transdisciplinary); collection of more epidemiological evidence in humans, cattle, and in small ruminants (which have been neglected in past research); Economic impact studies, including cost effectiveness of control programmes; livestock vaccination, including national facilities for securing vaccines for the cattle population; management of infected animals (with the ban on bovine slaughter, alternatives such as sanctuaries must be explored); laboratory capacities and diagnostics (quality must be assured and better rapid tests developed); and increased awareness, making farmers, health workers, and the general public more aware of risks of brucellosis and zoonoses in general. Overall, the meeting participants agreed that brucellosis control will be challenging in India, but with collaboration to address the priority areas listed here, it could be possible.

Seroprevalence of brucellosis and risk factors associated with its seropositivity in cattle, goats and humans in Iganga District, Uganda

Introduction

The burden of brucellosis among smallholder farmers is poorly-documented in Uganda. The disease burden is likely to be high, given the high levels of endemicity, lots of exposures and due to lack of control measures. In order to designate appropriate control measures, the magnitude and risk factors for brucellosis need to be known. We established the burden of and risk factors for Brucella seropositivity in cattle, goats, and humans in Iganga district, eastern Uganda.

Methods

A cross-sectional study was conducted in in Kigulamo Parish, Iganga District. We enrolled 226 households and administered a structured questionnaire to heads of households to capture data on socio-demographic characteristics, human brucellosis-related risk factors, and livestock farming practices. Human, cattle, and goat blood samples were collected and tested serologically using commercial indirect-ELISA kits manufactured by USDA, USA.

Results

Of 451 human blood samples, 20 (4.4%) were positive. Among 345 cattle blood samples, 4 (1.2%) were positive and among 351 goat blood samples, one (0.3%) was positive. Persons who reported consuming locally-made dairy products had 4 times higher odds of Brucella seropositivity (OR = 4.0, CI = 1.14-14.03, p = 0.031) than those who did not. None of the risk factors we asked about were significantly associated with seropositivity in cattle and goats.

Conclusion

The seroprevalence of brucellosis in humans in smallholder households in Kigulamo was relatively low and associated with consumption of locally made dairy products. No risk factors were significantly associated with seropositivity in livestock, likely due to the small number of seropositive animals. We recommend a One Health approach to control brucellosis simultaneously in animals and humans needed to sustainably reduce the burden of brucellosis in Uganda and beyond.

Spatial seroprevalence of bovine brucellosis in India-A large random sampling survey

Brucellosis caused by Brucella spp. is an important zoonosis and constitutes a serious public health hazard. In India, the disease is increasingly prevalent among bovine population with high zoonotic potential and negative impact on national economy. The investigation was conducted to study seroprevalence of brucellosis through random sample survey using survey tool box software. A total of 12,054 [cattle-9236, buffaloes-2818] bovine serum samples sourced from 15 states of India were tested by protein G indirect ELISA. The true prevalences of brucellosis observed in cattle and buffaloes were 8.3% and 3.6%, respectively. The highest prevalence of brucellosis was observed in the state of Punjab in both cattle and buffaloes (23.51 and 10.2%). Comparatively higher prevalence was recorded in cattle than the buffaloes in all the states except Manipur. The true prevalence greater than 5% was recorded in 8 and 3 states for cattle and buffaloes, respectively [(cattle- Punjab, Maharashtra, Rajasthan, Karnataka, Madhya Pradesh, Tamil Nadu, Gujarat and Kerala) and (buffaloes-Punjab, Gujarat and Manipur)] indicating wider prevalence of brucellosis. This study conclusively highlighted the seroprevalence of bovine brucellosis at state level which might be useful for prioritizing regions for vaccination, designing control strategies and improvisation of clinical surveillance system.

Sero-prevalence and associated risk factors of Brucellosis among Malaria negative febrile out-patients in Wakiso district, Central Uganda

Objective

Brucellosis is a zoonotic disease usually acquired through direct contact with the infected animals and consumption of contaminated milk and meat products. In humans Brucellosis presents similar signs with other febrile diseases like Malaria, typhoid and other febrile conditions. This study was carried out to determine the prevalence of Brucella abortus among patients with fever but were negative for Malaria.

Results

A cross-sectional study was carried out in Namayumba Health Centre IV, Wakiso district involving 200 participants. Blood samples was screened for B. abortus using Serum Agglutination Test and confirmed with Tube Agglutination test. A questionnaire was used to collect data on socio-demographic characteristics and human Brucellosis related risk factors. Human B. abortus sero-prevalence was at 7.5% (n = 200). The prevalence was high among participants aged 18–35 years (13.3%), muslims 12 (14.0%), those with no formal education (33.3%) and divorced 2 (14.3%). Consuming of raw milk (OR 2.162, 95% CI 0.021–1.379) and being a Muslim (OR 6.101, 95% CI 1.601–23.248) were associated with increased risk of Brucella abortus. It was concluded that human Brucella infection due to Brucella abortus is commonly associated with consumers of raw milk products and muslims in Wakiso district.

Brucellosis remains a neglected disease in the developing world: a call for interdisciplinary action

BACKGROUND

Brucellosis is an endemic zoonotic disease in most of the developing world that causes devastating losses to the livestock industry and small-scale livestock holders. Infected animals exhibit clinical signs that are of economic significance to stakeholders and include reduced fertility, abortion, poor weight gain, lost draught power, and a substantial decline in milk production. In humans, brucellosis typically manifests as a variety of non-specific clinical signs. Chronicity and recurring febrile conditions, as well as devastating complications in pregnant women are common sequelae.

DISCUSSION

In regions where the disease is endemic, brucellosis has far-reaching and deleterious effects on humans and animals alike. Deeply entrenched social misconceptions and fear of government intervention contribute to this disease continuing to smolder unchecked in most of the developing world, thereby limiting economic growth and inhibiting access to international markets. The losses in livestock productivity compromise food security and lead to shifts in the cognitive competency of the working generation, influence the propagation of gender inequality, and cause profound emotional suffering in farmers whose herds are affected. The acute and chronic symptoms of the disease in humans can result in a significant loss of workdays and a decline in the socioeconomic status of infected persons and their families from the associated loss of income. The burden of the disease to society includes significant human healthcare costs for diagnosis and treatment, and non-healthcare costs such as public education efforts to reduce disease transmission.

CONCLUSION

Brucellosis places significant burdens on the human healthcare system and limits the economic growth of individuals, communities, and nations where such development is especially important to diminish the prevalence of poverty. The implementation of public policy focused on mitigating the socioeconomic effects of brucellosis in human and animal populations is desperately needed. When developing a plan to mitigate the associated consequences, it is vital to consider both the abstract and quantifiable effects. This requires an interdisciplinary and collaborative, or One Health, approach that consists of public education, the development of an infrastructure for disease surveillance and reporting in both veterinary and medical fields, and campaigns for control in livestock and wildlife species.

Abortions in an organized dairy farm from North India reveal the possibility of breed susceptibility to Bovine Brucellosis

The present study was undertaken over a three year period (2012-2014) in an organized dairy farm located in North India to ascertain Brucella abortus as the putative cause of abortion. The dairy farm maintained cattle of Frieswal, Crossbred and Sahiwal breeds and followed calf-hood vaccination with Brucella abortus Strain 19 live vaccine in all the heifers. Even with the recommended vaccination schedule and good managemental practices in place, 88 cases of abortions clinically suspected of bovine brucellosis (40 from Frieswal breed, 17 from Crossbred cattle and 31 from Sahiwal breed) were reported from this farm. From these abortion cases, bacteriological isolation was possible in only four dams while 16 dams were found to be serologically positive in Serum Tube Agglutination Test (STAT). Molecular screening by PCR assay (specific for the bcsp31 gene of B. abortus) revealed that 24 dams were positive, out of which 20 were from Frieswal breed and rest four were from Crossbred herd. Prominently, all Sahiwal dams were found to be negative in bacteriological isolation and also in PCR assay. These results thus indicate towards the possibility of breed predisposition to abortions due to B. abortus infection. Statistical analysis by Fischer exact test (p < 0.01) too substantiated that breed susceptibility exists among these PCR positive cases. This study is novel as breed variation in abortions due to B. abortus in cattle is being documented for the first time. Seven representative PCR amplicons generated during the study were also sequenced and submitted to NCBI GenBank. Moreover, this study also accentuates the importance of PCR screening especially in vaccinated herd and raises concerns on over-dependence of serological assays when intensive vaccination is practised without any concomitant DIVA strategy. Thus, besides assisting in planning pragmatic control strategies against bovine brucellosis these findings are also imperative from 'One Health' context, also.

Bovine and Caprine Brucellosis in Bangladesh: Bayesian evaluation of four serological tests, true prevalence, and associated risk factors in household animals

A cross-sectional study was carried out to estimate the true prevalence of Brucella spp. and identify allied risk factors/indicators associated with brucellosis in the Dinajpur and Mymensingh districts of Bangladesh. A total 320 stratified random blood samples were collected and tested in parallel for Brucella antibodies using Rose Bengal (RBT), slow agglutination (SAT), and indirect and competitive ELISA. In addition, a structured questionnaire was administered to each household herd owner to gather information regarding potential risk factors. Both univariate and multivariate logistic regression analyses were used to identify potential risk factors or indicators at animal level. A Bayesian approach was used to estimate the true prevalence of brucellosis along with the test performances (Se and Sp). The estimated animal level true prevalence in cattle was 9.70 % (95 % CPI 5.0-16 %) and in goat 6.3 % (95 % CPI 2.8-11.0 %). The highest sensitivity was achieved by SAT ranges from 69.6 to 78.9 %, and iELISA was found to be more specific (97.4 to 98.8 %) in comparison with other tests. On the other hand, a significant level of (P < 0.05) Brucella seropositivity was found in cattle that breed naturally compared with those that undergo artificial insemination. In goats, exotic breeds were significantly associated (P < 0.05) with Brucella seroprevalence compared with indigenous breeds. Goats with a previous records of abortion and/or retained placenta were also found to have significant levels (P < 0.05). Cows with previous abortion records showed higher odds (18 times) of being seropositive. None of the evaluated tests can be recommended to apply alone for the diagnosis of bovine and caprine brucellosis.

Apparent seroprevalence, isolation and identification of risk factors for brucellosis among dairy cattle in Goa, India

Brucellosis is a highly contagious zoonotic infection affecting livestock and human beings. The disease has been reported worldwide except in few countries where it has been eradicated. The prevalence of brucellosis among cattle from 11 farms having a history of abortions was studied. A total of 481 samples comprising of blood, milk, vaginal swabs, vaginal discharges, placental tissues and fetal tissues were collected from 296 animals. Clinical samples were processed for the isolation of Brucella. Serum samples (n=296) were tested by Rose Bengal Plate Test (RBPT) and indirect ELISA. A total of 90 (30.40%) and 123 (41.55%) samples were positive by RBPT and indirect ELISA, respectively. Also 27.02% samples were positive by both the tests. Brucella isolates (n= 8) were recovered from clinical samples using Brucella selective media. All the isolates demonstrated PCR amplification for the bcsp31 and IS711 genes. Amplification of Brucella abortus specific primer was demonstrated by all the isolates in AMOS PCR indicating isolates to be of either B. abortus biotype 1, 2 or 4. Risk factors for transmission of brucellosis among cattle population were studied by field surveys. It was observed that lack of awareness about brucellosis (OR=8.739, P=0.138) and inadequate floor space (OR=0.278, P=0.128) were crucial risk factors for transmission of bovine brucellosis.

Retrospective and prospective perspectives on zoonotic brucellosis

Members of the genus Brucella are pathogenic bacteria exceedingly well adapted to their hosts. The bacterium is transmitted by direct contact within the same host species or accidentally to secondary hosts, such as humans. Human brucellosis is strongly linked to the management of domesticated animals and ingestion of their products. Since the domestication of ungulates and dogs in the Fertile Crescent and Asia in 12000 and 33000 ya, respectively, a steady supply of well adapted emergent Brucella pathogens causing zoonotic disease has been provided. Likewise, anthropogenic modification of wild life may have also impacted host susceptibility and Brucella selection. Domestication and human influence on wild life animals are not neutral phenomena. Consequently, Brucella organisms have followed their hosts’ fate and have been selected under conditions that favor high transmission rate. The “arm race” between Brucella and their preferred hosts has been driven by genetic adaptation of the bacterium confronted with the evolving immune defenses of the host. Management conditions, such as clustering, selection, culling, and vaccination of Brucella preferred hosts have profound influences in the outcome of brucellosis and in the selection of Brucella organisms. Countries that have controlled brucellosis systematically used reliable smooth live vaccines, consistent immunization protocols, adequate diagnostic tests, broad vaccination coverage and sustained removal of the infected animals. To ignore and misuse tools and strategies already available for the control of brucellosis may promote the emergence of new Brucella variants. The unrestricted use of low-efficacy vaccines may promote a “false sense of security” and works towards selection of Brucella with higher virulence and transmission potential.