Wildlife Tuberculosis Study Group

Bovine tuberculosis (BTB) is an exotic disease invading the buffalo population (Syncerus caffer) of the Kruger National Park (KNP), South Africa. We used a sex and age-structured epidemiological model to assess the effectiveness of a vaccination program and define important research directions. The model allows for dispersal between a focal herd and background population and was parameterized with a combination of published data and analyses of over 130 radio-collared buffalo in the central region of the KNP. Radio-tracking data indicated that all sex and age categories move between mixed herds, and males over 8 years old had higher mortality and dispersal rates than any other sex or age category. In part due to the high dispersal rates of buffalo, sensitivity analyses indicate that disease prevalence in the background population accounts for the most variability in the BTB prevalence and quasi-eradication within the focal herd. Vaccination rate and the transmission coefficient were the second and third most important parameters of the sensitivity analyses. Further analyses of the model without dispersal suggest that the amount of vaccination necessary for quasi-eradication (i.e. prevalence vaccine grants protection. Vaccination programs are more efficient (i.e. fewer wasted doses) when they focus on younger individuals. However, even with a lifelong vaccine and a closed population, the model suggests that >70% of the calf population would have to be vaccinated every year to reduce the prevalence to less than 1%. If the half-life of the vaccine is less than 5 years, even vaccinating every calf for 50 years may not eradicate BTB. Thus, although vaccination provides a means of controlling BTB prevalence it should be combined with other control measures if eradication is the objective

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Expansion of ecotourism-based industries, changes in land-use practices, and escalating competition for resources have increased contact between free-ranging wildlife and humans. Although human presence in wildlife areas may provide an important economic benefit through ecotourism, exposure to human pathogens may represent a health risk for wildlife. This report is the first to document introduction of a primary human pathogen into free-ranging wildlife. We describe outbreaks of Mycobacterium tuberculosis, a human pathogen, in free-ranging banded mongooses (Mungos mungo) in Botswana and suricates (Suricata suricatta) in South Africa. Wildlife managers and scientists must address the potential threat that humans pose to the health of free-ranging wildlife

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[unedited] The presence of bovine tuberculosis (Mycobacterium bovis) in the Kruger National Park (KNP) was determined for the first time in 1990. It was diagnosed in an African buffalo (Syncerus caffer) bull, which was found recumbent and in an emaciated and morbund state near the south-western boundary fence. This prompted an investigation into the bovine tuberculosis (BTB) status of the KNP, with emphasis on its epidemiological determinants and risk factors. This report documents the findings of surveys that were conducted from 1990 to 1996.It was found that BTB had entered the KNP ecosystem relatively recently (± 1960), and has found favourable circumstances for survival and propagation in a fully susceptible and immunologically naive buffalo population. Indications are that it entered the KNP from across the southern river boundary, where the presence of infected domestic cattle herds had been documented. From there the infection spread through the southern buffalo population and is currently spreading in a northward direction. It was estimated that this northward spread took place at a rate of about 6 km per year; the prospect being that, if this rate of spread is maintained, the entire KNP may be affected in less than 30 years from now. Spillover from buffalo had already occurred in species such as chacma baboon (Papio ursinus), lion (Panthera leo), cheetah (Acinonyx jubatus), kudu (Tragelaphus strepsiceros) and leopard (Panthera pardus). Although there is no indication yet that these species act as maintenance hosts, the possibility is raised that these, or as as yet overlooked species, might assume such a role in future.In the KNP, BTB manifests itself as a chronic and predominantly subclinical disease in buffalo. It may take years for clinical signs to develop, and then only at a terminal stage, when emaciation is a constant feature. It is suspected that the time from infection to death is variable and dependent on the animals's immune response, which can be weakened by such factors as stress, old age or droughts. It was found that, in the interim, buffalo have a normal reproductive life. On necropsy, buffalo show almost exclusively lung and upper respiratory tract involvement, pointing to an aerogenous mode of transmission. Histologically, little sing of encapsulation of lesions was detected, which suggests that they are exceptionally susceptible to BTB and that most lesions are open and infectious and progressive, leasing ultimately to death of the individual.Evidence also indicates that BTB is progressive whithin the herd context (92% being the highest prevalence rate thus far determined in a buffalo herd) as well as progressive within the KNP buffalo population (the implication being that virtually all buffalo herds in the KNP will eventually be infected).Preliminary data suggest a positive correlation between disease prevalence and mortality, with potential mortality reaching up to ten percent in buffalo herds having BTB prevalence rates of 50% and higher. Only the future will tell what the effect of the disease on the population dynamics of buffalo will be

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[unedited] Five kudus (Tragelaphus strepsiceros), three bulls and two cows, within the Greater Kruger National Park complex, were diagnosed with generalized tuberculosis caused by Mycobacterium bovis. The lesions seen in these animals were similar to those previously reported in kudus and includes severe tuberculous lymphadenitis of the nodes of the head and neck (that resulted in noticeable uni- or bilateral swelling beneath the ear), thorax, and the mesentery. All the animals also suffered from severe granulomatous pneumonia. The lesions in the lungs were more severe cranially and had a millary distribution elsewhere in the lungs. Based on the DNA patterns of the M. bovis isolates, at least some of these kudus were infected with strains commonly present in tuberculous buffaloes, lions, cheetahs, and baboons in the Park whereas other strains from these kudus were quite different and may reflect another source of infection. The presence of tuberculous kudus in the Park is expected to complicate control measures that may be instituted to contain or eradicate the disease in the Park

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Bovine tuberculosis (BTB) was first detected in Kruger National Park (KNP) in a single African buffalo (Syncerus caffer) in 1990. In 1991/1992, 2,071 African buffalo were examined for BTB as part of a culling program that removed animals from all known herds in KNP. The prevalence of BTB in 1991/1992 was estimated to be 0%, 4.4% (± 0.6%), and 27.1% (± 1.4%), in the north, central, and south zones of KNP, respectively. In 1998, a stratified, two-stage cluster sampling method was used to estimate that the prevalence of BTB was 1.5% (±2.5%), 16% (±5.3%), and 38.2% (±6.3%), in the north, central, and south zones, respectively. This represented a significant increase in prevalence (P <or= 0.05) in the south and central zones, but not in the north zone. Continued monitoring of BTB in KNP is important for understanding disease transmission risks, potential population effects, and the efficacy of disease management strategies. The methodology and sample sizes used in 1998 are appropriate for future BTB monitoring in KNP

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We examined data from 3,743 buffalo (Syncerus caffer) culled between 1991 and 1998 in Kruger National Park, South Africa, to evaluate effects of bovine tuberculosis on the buffalo population and examine risk factors of bovine tuberculosis. We found no evidence that bovine tuberculosis affected fertility or lactation status of female buffalo, but adult buffalo > three years old were underrepresented in infected herds. Logistic regression analysis demonstrated that older buffalo were at greater risk for bovine tuberculosis than younger buffalo and risk of acquiring bovine tuberculosis increased for all age groups as prevalence in the herd increased

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The authors discuss parasites and diseases commonly associated with the African buffalo. Techniques are outlined for breeding disease-free buffalo. pcp

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The authors discuss the occurrence, diagnosis and treatment of bovine tuberculosis in African buffalo, greater kudu, and Chacma baboons in the Kruger National Park, South Africa. pcp

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The authors discuss the occurrence, diagnosis and treatment of bovine tuberculosis in African buffalo, greater kudu, and Chacma baboons in the Kruger National Park, South Africa. pcp

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A single troop of free-ranging chacma baboons (Paplo ursinus) in Kruger National Park, South Africa, was found to be infected with tuberculosis caused by Mycobacterium bovis. It is assumed that some members of the troop originally became infected when feeding on a tuberculous carcass in the veld or on tuberculous material scavenged at a nearby post mortem facility. Subsequently, apparent aerosol transmission took place while the animals were sleeping in an unused room. Oral transmission probably also occurred due to continuous contamination of the floor of this room and the common, narrow access (a train bridge crossing the Sabi River) to it with faeces and urine. A macroscopic prevalence of 50% was found and the disease was noted to progress rapidly in infected baboons. A variety of organs had typical tuberculous lesions, of which the spleen, lungs, and mesenteric lymph nodes were consistently, grossly affected. Using Restriction Fragment Length Polymorphism analysis, all but one of the baboon isolates were found to be identical to the most common African buffalo (Syncerus caffer) isolate (genotype 1) in this park. The opportunistic sleeping facility was made inaccessible to the troop, which was forced to revert to sleeping in trees. A follow-up survey six months after closure, demonstrated that the disease had disappeared from the troop, and that no spillover infection had occurred into neighbouring troops

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The survival time of Mycobacterium bovis in the natural habitat of infected free ranging wildlife was investigated. Seven different experimental sites near Skukuza in the Kruger National Park, South Africa, were selected to expose macroscopically affected lung or lymph node tissue of African buffalo (Syncerus caffer) origin and spiked faecal specimens for various lengths of time over a 1-year period. Mycobacterium bovis could be isolated for a maximum period of 6 weeks from tissue specimens and 4 weeks from faeces. The longest survival of M. bovis in both specimen types was observed in winter and under moist conditions. Surprisingly, the survival time of M. bovis in buried specimens seemed greatly reduced to a maximum of 5 days

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The author discusses the relationships among livestock, bacterial diseases, and the transmission of disease (tuberculosis) to wild animals, lions in particular, in Kruger National Park, South Africa. pcp

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Free-ranging lions (Panthera leo) (n=3) and cheetahs (Acinonyx jubatus) (n=2) infected with Mycobacterium bovis were recorded for the first time in the Kruger National Park. It appears lions became infected after feeding on tuberculosis-infected African buffalo (Syncercus caffer) carcasses. It is uncertain how cheetahs got infected, but both species have been confirmed to be infected with the same strain found in African buffaloes. The presence of pulmonary lesions as apparently primary lesions in all involved cases suggests that both species may become maintenance reservoirs in this biodiverse ecosystem. The pulmonary lesions included tuberculous bronchiolitis and cavitation which would facilitate dissemination of M. bovis into the environment. Breeders of these species must be cautious not to feed meat from tuberculous carcasses and furthermore to be very selective about the origin of new introductions

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Bovine tuberculosis was diagnosed for the first time in an African buffalo in the Kruger National Park. The case was a two-year-old, emaciated bull, which had been found recumbent and obviously ill, near the south-western boundary of the KNP, in July 1990. Nine more suspected cases were found from nearby herds. Histopathologically, all nine of these animals had granulomatous lesions compatible with a diagnosis of mycobacteriosis, but acid-fast organisms could be demonstrated in only one animal

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Diseases that are emerging problems for wildlife in South Africa are discussed. These diseases include brucellosis in Cape buffalo and hippopotami; bovine tuberculosis in lechwe, Cape buffalo, greater kudu and grey duiker; encephalitis, ulcerative pododermatitis, and "floppy trunk" syndrome in African elephants; infectious "capped elbow", canine distemper and feline immunodeficiency virus in lions; and rinderpest and parafilariasis in Cape buffalo. lgh

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The authors discuss the likelihood that tuberculosis has been spread from buffaloes to a cheetah, a lion, and a chacma baboon in the Kruger National Park, South Africa

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Two known major foci of TB-infected buffaloes exist in South Africa: one in the Kruger National Park and the second in the Hluhluwe-Umfolozi Park in KwaZulu-Natal. The disease in buffaloes spread rapidly within infected herds to reach prevalence rates of up to 75 percent. Up to 10 percent of infected animals at any one time suffer from generalized tuberculosis; these animals usually die of the infection. Current governmental control measures are applied to limit the movement of TB-infected buffaloes

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