Modelling the control of bovine brucellosis in India.

Brucellosis imposes substantial impacts on livestock production and public health worldwide. A stochastic, age-structured model incorporating herd demographics was developed describing within- and between-herd transmission of Brucella abortus in dairy cattle herds. The model was fitted to data from a cross-sectional study conducted in Punjab State of India and used to evaluate the effectiveness of control strategies under consideration. Based on model results, stakeholder acceptance and constraints regarding vaccine supply, vaccination of replacement calves in large farms should be prioritized. Test and removal applied at early stages of the control programme where seroprevalence is high would not constitute an effective or acceptable use of resources because significant numbers of animals would be 'removed' (culled or not used for breeding) based on false positive results. To achieve sustained reductions in brucellosis, policymakers must commit to maintaining vaccination in the long term, which may eventually reduce frequency of infection in the livestock reservoir to a low enough level for elimination to be a realistic objective. This work provides key strategic insights into the control of brucellosis in India, which has the largest cattle population globally, and a general modelling framework for evaluating control strategies in endemic settings.

Detection of serum neutralizing antibodies to Simbu sero-group viruses in cattle in Tanzania.

BACKGROUND: Orthobunyaviruses belonging to the Simbu sero-group occur worldwide, including the newly recognized Schmallenberg virus (SBV) in Europe. These viruses cause congenital malformations and reproductive losses in ruminants. Information on the presence of these viruses in Africa is scarce and the origin of SBV is unknown. The aim of this study was to investigate the presence of antibodies against SBV and closely related viruses in cattle in Tanzania, and their possible association with reproductive disorders. RESULTS: In a cross-sectional study, serum from 659 cattle from 202 herds collected in 2012/2013 were analyzed using a commercial kit for SBV ELISA, and 61 % were positive. Univariable logistic regression revealed significant association between ELISA seropositivity and reproductive disorders (OR = 1.9). Sera from the same area collected in 2008/2009, before the SBV epidemic in Europe, were also tested and 71 (54.6 %) of 130 were positive. To interpret the ELISA results, SBV virus neutralization test (VNT) was performed on 110 sera collected in 2012/2013, of which 51 % were positive. Of 71 sera from 2008/2009, 21 % were positive. To investigate potential cross reactivity with related viruses, 45 sera from 2012/2013 that were positive in SBV ELISA were analyzed in VNTs for Aino, Akabane, Douglas, Peaton, Sabo, SBV, Sathuperi, Shamonda, Simbu and Tinaroo viruses. All 45 sera were positive for one or more of these viruses. Twenty-nine sera (64.4 %) were positive for SBV, and one had the highest titer for this virus. CONCLUSIONS: This is the first indication that Aino, Akabane, Douglas, Peaton, Sabo, SBV, Sathuperi, Shamonda and Tinaroo viruses circulate and cause negative effect on reproductive performance in cattle in Tanzania. SBV or a closely related virus was present before the European epidemic. However, potential cross reactivity complicates the interpretation of serological studies in areas where several related viruses may circulate. Virus isolation and molecular characterization in cattle and/or vectors is recommended to further identify the viruses circulating in this region. However, isolation in cattle is difficult due to short viremic period of 2 to 6 days, and isolation in vectors does not necessarily reflect the situation in cattle.

First isolation, identification, phenotypic and genotypic characterization of Brucella abortus biovar 3 from dairy cattle in Tanzania.

BACKGROUND: Brucellosis is a disease of worldwide public health and economic importance. Successful control is based on knowledge of epidemiology and strains present in an area. In developing countries, most investigations are based on serological assays. This study aimed at investigating a dairy herd experiencing abortions in order to establish within-herd seroprevalence to Brucella spp., identify, characterize Brucella strains by Multiple Loci Variable Number of Tandem Repeats Analysis (MLVA-VNTR) and investigate possible spillover to other species. RESULTS: The within-herd seroprevalence in cattle (n = 200) was 48 % (95 % CI 41-55), using an indirect ELISA, while the Rose Bengal Test (RBT) yielded lower prevalence (21.5 %; 95 % CI 16-27). Two sheep (n = 35) and one goat (n = 50) were seropositive using ELISA while none of the dogs (n = 6) was positive with the RBT. Three Brucella were isolated from an aborted fetus and associated membranes. Real time PCR (IS711), Bruce-ladder and classical biotyping classified the isolates as B. abortus biovar 3. MLVA-VNTR revealed two different but closely related genotypes. The isolates showed unique profiles, providing the first genotypic data from Tanzania. These genotypes were not related to B. abortus biovar 3 reference strain Tulya originally isolated from a human patient in Uganda in 1958, unlike the genotypes isolated and characterized recently in Kenya. High within-herd prevalence, isolation of the pathogen and abortion confirm that B. abortus is circulating in this herd with cattle as reservoir hosts. A low seroprevalence in sheep and goats suggests a spillover of B. abortus from cattle to small ruminants in the herd. CONCLUSIONS: This is the first isolation and characterization of B. abortus biovar 3 from a dairy cow with abortion in Tanzania. The origin of the Tanzanian genotypes remain elusive, although they seem to be related to genotypes found in Europe, Turkey and China but not related to B. abortus biovar 3 reference strain or genotypes from Kenya. Importantly, replacement heifers are commonly sourced from large farms like this to smallholder farmers, which poses risk of spread of bacteria to other herds. B. abortus is a significant zoonotic risk and animal health problem in this production system, therefore further studies on humans is recommended.

An assessment of zoonotic and production limiting pathogens in rusa deer (Cervus timorensis rusa) from Mauritius.

A population of approximately 70,000 rusa deer (Cervus timorensis russa) represents the most important mammal species reared for food on the island of Mauritius, being the main source of red meat for the local population. However, very limited information is available on the circulation of pathogens affecting the productivity and health of this species. To produce baseline data on the circulation of infectious pathogens in rusa deer under production, a serological survey and/or direct pathogen detection for six selected infectious diseases was undertaken in 2007 in a sample of 53% of the herds reared in semi-free-ranging conditions in hunting estates. Seropositive results were recorded for Johne's disease with an indirect ELISA test (1.7%, n = 351), heartwater with an immunofluorescence antibody test (IFAT) (95.5%, n = 178) and leptospirosis with a Microscopic Agglutination Test (MAT) (25.9%, n = 363). Significant associations were found between seroprevalence to some of the leptospiral serogroups detected (Tarassovi, Pomona, Sejroe and Mini) and age of the animals, animal density or location of the estates (being more prevalent in hotter and more humid areas). In addition, Mycobacterium bovis and M. avium subspecies paratuberculosis were confirmed in two deer carcasses by culture and PCR, respectively. No antibodies against Brucella spp. nor Rift Valley Fever virus were detected with the use of respective indirect ELISA's. The results obtained suggest that the population of rusa deer from Mauritius is exposed to a wide range of pathogens which may affect their productivity. In addition, the results highlight the potential public health risks incurred by deer industry workers and consumers. This survey fills an important gap in knowledge regarding the health of tropical deer meat in Mauritius and justifies the need to implement more regular surveys of selected pathogens in the deer population.

The quest for a true One Health perspective of brucellosis.

One Health is an interdisciplinary collaboration that aims at mitigating risks to human health arising from microorganisms present in non-human animal species, which have the potential to be transmitted and cause disease in humans. Different degrees of scientific collaboration and sectoral integration are needed for different types of zoonotic diseases, depending on the health and associated economic gains that can be expected from a One Health approach. Indeed, mitigating zoonotic risks related to emerging diseases with pandemic potential is different from mitigating risks related to endemic zoonotic diseases like brucellosis. Likewise, management of brucellosis at the wildlife-livestock interface in wildlife conservation areas is in essence different from mitigating transmission of a given Brucella species within its preferential host species, which in turn is different from mitigating the spillover of a given Brucella species to non-preferential host species, humans included. Brucellosis economic models often oversimplify and/or wrongly assess transmission between reservoir hosts and spillover hosts. Moreover,they may not properly value non-market outcomes, such as avoidance of human disease, consumer confidence and conservation biology issues. As a result, uncertainty is such that the economic predictions of these models can be questionable. Therefore, understanding the infection biology of Brucella species is a prerequisite. This paper reviews and highlights important features of the infection biology of Brucella species and the changing epidemiology of brucellosis that need to be integrated into a true One Health perspective of brucellosis.

Seroprevalence of brucellosis in sheep and isolation of Brucella abortus biovar 6 in Kassala State, Eastern Sudan.

Brucellosis is one of the important zoonotic diseases among livestock. This study was carried out to estimate the prevalence of brucellosis and isolate Brucella spp. in sheep in Kassala State in the east of Sudan. Two thousand and five serum samples were randomly collected from nine different localities. All serum samples were examined by the Rose Bengal plate test (RBPT) and the modified RBPT (mRBPT). Forty-three (2.15%, 95% confidence interval [CI]: 1.6,3.0) and 68 (3.4%, 95% CI: 2.6, 4.2) samples were positive with the RBPT and the mRBPT, respectively. According to a known diagnostic sensitivity of 86.6% and a known diagnostic specificity of 97.6% for the mRBPT, the true prevalence was estimated to be 1.2% (95% CI: 0.3, 2.2). Different tissue samples were collected from 41 mRBPT seropositive animals. Brucella abortus biovar 6 was isolated from a pyometra of a seropositive ewe. It is important to note that B. abortus biovar 6 cannot be differentiated from Brucella melitensis biovar 2 by routine bacteriology. Only phage typing performed in reference laboratories will allow accurate identification of the strain. The fact that B. abortus biovar 6 does not require CO2 for growth, combined with the fact that it has been isolated from a small ruminant in this study, could easily have led to misidentification (as B. melitensis biovar 2), to wrong epidemiological inferences and to the implementation of inappropriate control measures. The results presented here suggest that sheep are spillover hosts, as previously described for camels, and that the actual reservoir of B. abortus biovar 6 is cattle in Kassala State, Eastern Sudan. This study highlights the importance of isolating and identifying Brucella spp. in different livestock species in order to accurately decipher brucellosis epidemiology in sub-Saharan Africa.

Brucellosis in terrestrial wildlife.

The epidemiological link between brucellosis in wildlife and brucellosis in livestock and people is widely recognised. When studying brucellosis in wildlife, three questions arise: (i) Is this the result of a spillover from livestock or a sustainable infection in one or more host species of wildlife? (ii) Does wildlife brucellosis represent a reservoir of Brucella strains for livestock? (iii) Is it of zoonotic concern? Despite their different host preferences, B. abortus and B. suis have been isolated from a variety of wildlife species, whereas B. melitensis is rarely reported in wildlife. The pathogenesis of Brucella spp. in wildlife reservoirs is not yet fully defined. The prevalence of brucellosis in some wildlife species is very low and thus the behaviour of individual animals, and interactions between wildlife and livestock, may be the most important drivers for transmission. Since signs of the disease are non-pathognomonic, definitive diagnosis depends on laboratory testing, including indirect tests that can be applied to blood or milk, as well as direct tests (classical bacteriology and methods based on the polymerase chain reaction [PCR]). However, serological tests cannot determine which Brucella species has induced anti-Brucella antibodies in the host. Only the isolation of Brucella spp. (or specific DNA detection by PCR) allows a definitive diagnosis, using classical or molecular techniques to identify and type specific strains. There is as yet no brucellosis vaccine that demonstrates satisfactory safety and efficacy in wildlife. Therefore, controlling brucellosis in wildlife should be based on good management practices. At present, transmission of Brucella spp. from wildlife to humans seems to be linked to the butchering of meat and dressing of infected wild or feral pig carcasses in thedeveloped world, and infected African buffalo in the developing world. In the Arctic, the traditional consumption of raw bone marrow and the internal organs of freshly killed caribou or reindeer is an important risk factor.

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.

Seroepidemiological study of livestock brucellosis in a pastoral region.

A seroepidemiological study of Brucella infections in multiple livestock species in the Borana pastoral system of Ethiopia was performed between December 2007 and October 2008. A cross-sectional multi-stage sampling technique was employed to select 575 cattle, 1073 camels and 1248 goats from the target populations. Sera were collected from the animals, and serially tested using Rose Bengal test and complement fixation test. Overall prevalence and prevalence with respect to explanatory variables were established, and potential risk factors for seropositivity were analysed using a multivariable logistic regression. The results showed that 8·0% (95% CI 6·0-10·6), 1·8% (95% CI 1·1-2·8) and 1·6% (95% CI 1·0-2·5) of the tested cattle, camels and goats, respectively, had antibodies to Brucella antigen. Positive reactors were found in 93·8% of the villages with more frequent detection of positive cattle (93·3%) than camels (56·3%) and goats (37·5%). Risk factors identified for cattle were: keeping more livestock species at household level (OR 4·1, 95% CI 1·9-8·9), increasing age of the animal (OR 2·8, 95% CI 1·3-6·0) and wet season (OR 3·3, 95% CI 1·6-6·9). Increase in household-level species composition (OR 4·1, 95% CI 1·2-14·2) and wet season (OR 3·7, 95% CI 1·5-9·1) were found to be risk factors for seropositivity in camels and goats, respectively. Existence of more than one seroreactor animal species in most villages and association of increased livestock species composition with seropositivity may add more credence to the possibility of cross-species transmission of Brucella infections. Although no attempt to isolate Brucella spp. was made, our results suggest that cattle are more likely maintenance hosts of Brucella abortus which has spread to goats and camels. This should be substantiated by further isolation and identification of Brucella organisms to trace the source of infection and transmission dynamics in various hosts kept under mixed conditions. In conclusion, the present study suggests the need for investigating a feasible control intervention and raising public awareness on prevention methods of human exposure to brucellosis.

Brucellosis at the animal/ecosystem/human interface at the beginning of the 21st century.

Following the recent discovery of new Brucella strains from different animal species and from the environment, ten Brucella species are nowadays included in the genus Brucella. Although the intracellular trafficking of Brucella is well described, the strategies developed by Brucella to survive and multiply in phagocytic and non-phagocytic cells, particularly to access nutriments during its intracellular journey, are still largely unknown. Metabolism and virulence of Brucella are now considered to be two sides of the same coin. Mechanisms presiding to the colonization of the pregnant uterus in different animal species are not known. Vaccination is the cornerstone of control programs in livestock and although the S19, RB51 (both in cattle) and Rev 1 (in sheep and goats) vaccines have been successfully used worldwide, they have drawbacks and thus the ideal brucellosis vaccine is still very much awaited. There is no vaccine available for pigs and wildlife. Animal brucellosis control strategies differ in the developed and the developing world. Most emphasis is put on eradication and on risk analysis to avoid the re-introduction of Brucella in the developed world. Information related to the prevalence of brucellosis is still scarce in the developing world and control programs are rarely implemented. Since there is no vaccine available for humans, prevention of human brucellosis relies on its control in the animal reservoir. Brucella is also considered to be an agent to be used in bio- and agroterrorism attacks. At the animal/ecosystem/human interface it is critical to reduce opportunities for Brucella to jump host species as already seen in livestock, wildlife and humans. This task is a challenge for the future in terms of veterinary public health, as for wildlife and ecosystem managers and will need a "One Health" approach to be successful.

Brucella seroprevalence of the Kafue lechwe (Kobus leche kafuensis) and Black lechwe (Kobus leche smithemani): exposure associated to contact with cattle.

We investigated Brucella seroprevalence in Kafue (Kobus leche kafuensis) and Black (Kobus leche smithemani) lechwe antelopes to assess Brucella infections in relation to presence/absence of cattle interaction on the wetlands. Accordingly, two study populations based on cattle interaction were assesed: Kafue lechwe from Kafue flats which interact with cattle; and the Black lechwe with no known interaction with cattle from the Bangweulu swamps. Fourteen Kafue lechwe and thirty Black lechwe were slaughtered between October and December 2009 using special research licenses obtained from the Zambia wildlife authority to investigate diseases in lechwe antelope. For the purpose of this study, blood was collected and sera separated for Rose Bengal and indirect ELISA tests. Seroprevalence of Brucella in the Kafue lechwe was estimated at 42.9% [95% CI: 15.2-70.5] while that in Black lechwe was 0% [95% CI:0.0-11.6]. On the Kafue flats, cattle were spotted grazing in the same areas as lechwe while there was no evidence of cattle presence on the Bangweulu swamps. These differences in seroprevalence between Kafue lechwe and Black lechwe were assumed to be associated with interaction between Kafue lechwe and Brucella infected cattle, and no such contact existed between cattle and the Black lechwe. Our study suggests that brucellosis in the Kafue lechwe may have originated from cattle but has now established a reservoir in wild animals. It is also important to keep in mind that the Black lechwe can easily become infected with Brucella spp. once cattle are introduced in the surrounding areas.

Molecular epidemiology of human and animal tuberculosis in Ibadan, Southwestern Nigeria.

From 2005 to 2007, Mycobacterium tuberculosis complex (MTC) strains were isolated from cattle, goats and pigs samples collected at the Bodija abattoir and from human samples from tuberculosis patients and livestock traders at the Akinyele cattle market in Ibadan, Southwestern Nigeria. Seventy four isolates obtained from humans (24) and livestock (50) were identified as MTC strains. Thirty two isolates were spoligotyped. Nineteen of these 32 isolates were identified as M. tuberculosis whilst 13 were identified as Mycobacterium bovis. M. bovis was isolated from two humans, whereas M. tuberculosis was isolated from a bovine, a pig and a goat. All the M. bovis isolates identified in this study belonged to the Africa 1 clonal complex. Multiple locus VNTR [variable number of tandem repeats] analysis (MLVA) was carried out on the 74 isolates. Three major clusters were defined. Group A consisted of 24 M. tuberculosis isolates (MLVA genotypes 1-18). One strain was isolated from a bovine and one from a pig. Group B consisted of 49 M. bovis strains (MLVA genotypes 19-48), mainly of cattle origin but also included four goat, nine pig and two human isolates. Group C consisted of a single M. tuberculosis isolate (MLVA genotype 49) obtained from a goat. Spoligotyping and MLVA confirmed it as clustering with the East Africa Indian clade found in humans in Sudan and the Republic of Djibouti. The isolation of three M. tuberculosis strains from livestock raises the question of their epidemiological importance as a source of infection for humans.

Monitoring of the intra-dermal tuberculosis skin test performed by Belgian field practitioners.

The present study aimed to monitor skin test practices as performed by veterinarian field practitioners in Belgium. For this purpose, an anonymous postal questionnaire was elaborated and dispatched to veterinarians involved in bovine tuberculosis detection. The questionnaire included items focusing on the skin test performance. International experts in the field of bovine tuberculosis were asked to fill the questionnaire and a scoring scale was built as follows: 0 = 'ideal' answer, 1 = acceptable answer, whereas 2 = unacceptable answer. Furthermore, experts were asked to rank the questionnaire's items according to their possible impact on the risk of not detecting reactors. A global score was further calculated for each participant and a comparison of practices was carried out between the two regions of the country, i.e. Wallonia and Flanders. Significant differences were observed between both regions, a harmonization at the country level is thus essential. No veterinarian summed a null score, corresponding to the ideal skin test procedure, which suggests that skin-testing is far from being performed correctly. Field practitioners need to be sensitized to the importance of correctly performing the test. The authors recommend the questionnaire is suitable for application in other countries or regions.

Comparison of the capillary and agarose electrophoresis based multiple locus VNTR (variable number of tandem repeats) analysis (MLVA) on Mycobacterium bovis isolates.

Electrophoretic techniques that can be used for genotyping of bacterial pathogens ranges from manual, low-cost, agarose gels to high-throughput capillary electrophoresis sequencing machines. These two methods are currently employed in the electrophoresis of PCR products used in multiple locus VNTR (variable number of tandem repeats) analysis (MLVA), i.e. the agarose electrophoresis (AE) and the capillary electrophoresis (CE). Some authors have suggested that clusters generated by AE are less reliable than those generated by CE and that the latter is a more sensitive technique than the former when typing Mycobacterium tuberculosis complex (MTC) isolates. Because such a claim could have significant consequences for investigators in this field, a comparison was made on 19 Belgian Mycobacterium bovis strains which had previously been genotyped using CE VNTR analysis. The VNTR profiles of the CE VNTR analysis were compared with those obtained by AE VNTR analysis at 14 VNTR loci. Our results indicated that there were no differences in copy numbers at all loci tested when the copy numbers obtained by the AE VNTR analysis were compared with those obtained by CE VNTR analysis. The use of AE VNTR analysis in mycobacterial genotyping does not alter the sensitivity of the MLVA technique compared with the CE VNTR analysis. The AE VNTR can therefore be regarded as a viable alternative in moderately equipped laboratories that cannot afford the expensive equipment required for CE VNTR analysis and data obtained by AE VNTR analysis can be shared between laboratories which use the CE VNTR method.

Zoonotic tuberculosis and brucellosis in Africa: neglected zoonoses or minor public-health issues? The outcomes of a multi-disciplinary workshop.

Late in 2007, veterinary, medical and anthropological professionals from Europe and Africa met in a 2-day workshop in Pretoria, South Africa, to evaluate the burden, surveillance and control of zoonotic tuberculosis and brucellosis in sub-Saharan Africa. Keynote presentations reviewed the burden of these diseases on human and livestock health, the existing diagnostic tools, and the available control methods. These presentations were followed by group discussions and the formulation of recommendations. The presence of Mycobacterium bovis and Brucella spp. in livestock was considered to be a serious threat to public health, since livestock and animal products are the only source of such infections in human beings. The impact of these pathogens on human health appears to be relatively marginal, however, when compared with Mycobacterium tuberculosis infections and drug resistance, HIV and malaria. Appropriate diagnostic tools are needed to improve the detection of M. bovis and Brucella spp. in humans. In livestock, the 'test-and-slaughter' approach and the pasteurization of milk, which have been used successfully in industrialized countries, might not be the optimal control tools in Africa. Control strategies should fit the needs and perceptions of local communities. Improved intersectoral and international collaboration in surveillance, diagnosis and control, and in the education of medical and veterinary personnel, are advocated.

Mycobacterium tuberculosis and Mycobacterium africanum in stools from children attending an immunization clinic in Ibadan, Nigeria.

BACKGROUND: Tuberculosis is a major cause of childhood morbidity and mortality in Nigeria. Diagnosis of childhood tuberculosis is a global challenge making early treatment a mirage. In this study we investigated the stools of children for the presence of mycobacteria. METHODS: Stool samples from children aged 3 days to 3 years who presented for postnatal immunization at a large university-based clinic in Nigeria, were subjected to Ziehl-Neelsen staining. Samples with acid-fast bacilli were further processed using mycobacterial culture, spoligotyping, and deletion typing. RESULTS: One hundred and ninety-two stool samples from different children were collected and processed. Thirty (15.6%) had acid-fast bacilli. Of these, eight had Mycobacterium tuberculosis and one had Mycobacterium africanum. CONCLUSIONS: Approximately 5% (9/192) of apparently well children had evidence of potentially serious tuberculosis infection. The usefulness of stool specimens for diagnosing pediatric tuberculosis warrants further investigation.

The role of Brucella infection in abortions among traditional cattle reared in proximity to wildlife on the Kafue flats of Zambia.

The role of Brucella infections in cattle abortions was investigated in 914 females from 124 herds. Animals were tested for exposure to Brucella species and history of abortion over the past three years. Sera were tested using the Rose Bengal test (RBT) and competitive enzyme-linked immunosorbent assay (c-ELISA). Of 886 females tested, 189 were positive on RBT, and 154 (81.5%) were confirmed by c-ELISA. At the individual animal level, 16.2% (95% confidence interval [CI]: 12.6% to 19.8%) of the cows had aborted their foetuses in the last three years, while Brucella seroprevalence was estimated at 23.9% (95% CI: 19.8% to 28.0%), after adjusting for area clustering and weighting according to sampling fraction. At the herd level, abortions were recorded in 50% of the herds (95% CI: 41.2% to 58.8%) and the seroprevalence was 58.1% (95% CI: 49.5% to 66.6%). A multiple logistic regression model identified the presence of anti-Brucella antibodies (odds ratio = 3.4; 95% CI: 1.6 to 7.4) and age as having significant effects on the risk of cattle abortion but no distinct factors could be identified at herd level. These results establish that Brucella infections contribute significantly to cattle abortions in the traditional livestock sector of Zambia.

Cloning, sequencing and expression of white rhinoceros (Ceratotherium simum) interferon-gamma (IFN-gamma) and the production of rhinoceros IFN-gamma specific antibodies.

Bovine tuberculosis (BTB) is endemic in African buffalo (Syncerus caffer) in the Kruger National Park (KNP). In addition to buffalo, Mycobacterium bovis has been found in at least 14 other mammalian species in South Africa, including kudu (Tragelaphus strepsiceros), Chacma baboon (Papio ursinus) and lion (Panthera leo). This has raised concern about the spillover into other potentially susceptible species like rhinoceros, thus jeopardising breeding and relocation projects aiming at the conservation of biodiversity. Hence, procedures to screen for and diagnose BTB in black rhinoceros (Diceros bicornis) and white rhinoceros (Ceratotherium simum) need to be in place. The Interferon-gamma (IFN-gamma) assay is used as a routine diagnostic tool to determine infection of cattle and recently African buffalo, with M. bovis and other mycobacteria. The aim of the present work was to develop reagents to set up a rhinoceros IFN-gamma (RhIFN-gamma) assay. The white rhinoceros IFN-gamma gene was cloned, sequenced and expressed as a mature protein. Amino acid (aa) sequence analysis revealed that RhIFN-gamma shares a homology of 90% with equine IFN-gamma. Monoclonal antibodies, as well as polyclonal chicken antibodies (Yolk Immunoglobulin-IgY) with specificity for recombinant RhIFN-gamma were produced. Using the monoclonals as capture antibodies and the polyclonal IgY for detection, it was shown that recombinant as well as native white rhinoceros IFN-gamma was recognised. This preliminary IFN-gamma enzyme-linked immunosorbent assay (ELISA), has the potential to be developed into a diagnostic assay for M. bovis infection in rhinoceros.

Wildlife tuberculosis in South African conservation areas: implications and challenges.

Tuberculosis, caused by Mycobacterium bovis, was first diagnosed in African buffalo in South Africa's Kruger National Park in 1990. Over the past 15 years the disease has spread northwards leaving only the most northern buffalo herds unaffected. Evidence suggests that 10 other small and large mammalian species, including large predators, are spillover hosts. Wildlife tuberculosis has also been diagnosed in several adjacent private game reserves and in the Hluhluwe-iMfolozi Park, the third largest game reserve in South Africa. The tuberculosis epidemic has a number of implications, for which the full effect of some might only be seen in the long-term. Potential negative long-term effects on the population dynamics of certain social animal species and the direct threat for the survival of endangered species pose particular problems for wildlife conservationists. On the other hand, the risk of spillover infection to neighboring communal cattle raises concerns about human health at the wildlife-livestock-human interface, not only along the western boundary of Kruger National Park, but also with regards to the joint development of the Greater Limpopo Transfrontier Conservation Area with Zimbabwe and Mozambique. From an economic point of view, wildlife tuberculosis has resulted in national and international trade restrictions for affected species. The lack of diagnostic tools for most species and the absence of an effective vaccine make it currently impossible to contain and control this disease within an infected free-ranging ecosystem. Veterinary researchers and policy-makers have recognized the need to intensify research on this disease and the need to develop tools for control, initially targeting buffalo and lion.