Mycobacteriosis in slaughter pigs from South Africa from 1991 to 2002: Mycobacterium spp. diversity and Mycobacterium avium complex genotypes.

Introduction: Mycobacterium avium complex (MAC) bacteria are the most prominent etiological agents of lymphadenitis in pigs. M. avium subspecies hominissuis (MAH) is a member of MAC and has been reported in many parts of the world to be the most prevalent non-tuberculous mycobacteria (NTM) to cause mycobacteriosis in humans, mainly in children. Thus, the economic and zoonotic impact of MAC species are increasingly being recognized. In South Africa, little is known about the distribution of NTM and the molecular epidemiology of M. avium in pigs. Materials and methods: In this study, lymph nodes including mandibular, mesenteric, submandibular, and retropharyngeal, with tuberculosis-like lesions were collected during routine meat inspection of slaughter pigs with no disease symptoms (n = 132), between 1991 and 2002. These pigs were slaughtered at 44 abattoirs distributed across seven of the nine South African provinces. Mycobacterial culture, polymerase chain reaction (PCR), and sequencing of the Mycobacterium specific 577 bp 16S rRNA gene fragment were performed for species and subspecies identification. Results: The majority of the isolates (each per sample); 114 (86.4%) were identified as MAH, 8 (6%) as MAA/M. avium subsp. silvaticum, 4 (3%) were Mycobacterium tuberculosis, 2 (1.5%) as Mycobacterium intracellulare, and 1 (0.75%) as Mycobacterium bovis. The other isolates were identified as Mycobacterium lentiflavum (0.75%), Mycobacterium novocastrense (0.75%), and a Micrococcus spp. (0.75%). Using an eight-marker MLVA typing tool, we deciphered at least nine MIRU VNTR INMV types of MAH and MAA. Discussion: Identification of known zoonotic mycobacteria, including MAH, MAA, M. intracellulare, M. bovis, and M. tuberculosis, from slaughter pigs has a potential public health impact and also strengthens recognition of the potential economic impact of MAC. This study has also for the first time in South Africa, revealed MAC MIRU VNTR INMV genotypes which will aid in the future epidemiological investigation of MAC in South Africa.

Risk practices for bovine tuberculosis transmission to cattle and livestock farming communities living at wildlife-livestock-human interface in northern KwaZulu Natal, South Africa.

Bovine tuberculosis (bTB) is a disease of cattle that is transmitted through direct contact with an infected animal or ingestion of contaminated food or water. This study seeks to explore the local knowledge on bTB, obtain information on social and cultural practices regarding risk of bTB transmission to cattle and humans (zoonotic TB) in a traditional livestock farming community with a history of bTB diagnosis in cattle and wildlife. Information was collected using a qualitative approach of Focus Group Discussions (FGDs) targeting household members of livestock farmers that owned bTB tested herds. We conducted fourteen FGDs (150 individuals) across four dip tanks that included the following categories of participants from cattle owning households: head of households, herdsmen, dip tank committee members and women. The qualitative data was managed using NVivo Version 12 Pro software. Social and cultural practices were identified as major risky practices for bTB transmission to people, such as the consumption of undercooked meat, consumption of soured /raw milk and lack of protective measures during slaughtering of cattle. The acceptance of animals into a herd without bTB pre-movement testing following traditional practices (e.g. lobola, 'bride price', the temporary introduction of a bull for 'breeding'), the sharing of grazing and watering points amongst the herds and with wildlife were identified as risky practices for M. bovis infection transmission to cattle. Overall, knowledge of bTB in cattle and modes of transmission to people and livestock was found to be high. However, the community was still involved in risky practices that expose people and cattle to bovine TB. An inter-disciplinary 'One Health' approach that engages the community is recommended, to provide locally relevant interventions that allows the community to keep their traditional practices and socio-economic systems whilst avoiding disease transmission to cattle and people.

Prevalence of Mycobacterium bovis infection in traditionally managed cattle at the wildlife-livestock interface in South Africa in the absence of control measures.

Cattle are the domestic animal reservoir for Mycobacterium bovis (M. bovis) which also affects other domestic animals, several wildlife species and humans leading to tuberculosis. The study area is in a resource-poor community that is surrounded by several game parks, where M. bovis infection has been previously diagnosed in wildlife. A cross-sectional study was carried out to determine the prevalence of M. bovis infection in 659 cattle from a total of 192 traditionally managed herds using the BOVIGAM® interferon gamma assay (IFN-γ). Infection was confirmed by post mortem examination and M. bovis isolation from three test-positive cattle. Genotyping of the M. bovis isolates was done using spoligotyping and VNTR (variable number of tandem repeats typing). The apparent M. bovis prevalence rate in cattle at animal level was 12% with a true population prevalence of 6% (95% Confidence interval (C.I) 3.8 to 8.1) and a herd prevalence of 28%. Spoligotyping analysis revealed that the M. bovis isolates belonged to spoligotype SB0130 and were shared with wildlife. Three VNTR profiles were identified among the SB0130 isolates from cattle, two of which had previously been detected in buffalo in a game reserve adjacent to the study area. The apparent widespread presence of M. bovis in the cattle population raises a serious public health concern and justifies further investigation into the risk factors for M. bovis transmission to cattle and humans. Moreover, there is an urgent need for effective bTB control measures to reduce infection in the communal cattle and prevent its spread to uninfected herds.

Progenitor strain introduction of Mycobacterium bovis at the wildlife-livestock interface can lead to clonal expansion of the disease in a single ecosystem.

Mycobacterium bovis infects multiple wildlife species and domesticated cattle across South Africa, and negatively impacts on livestock trade and movement of wildlife for conservation purposes. M. bovis infection was first reported in the Kruger National Park (KNP) in South Africa during the 1990s, and has since spread to infect numerous animal host species throughout the park and across South Africa. Whole genome sequencing data of 17 M. bovis isolates were analyzed to investigate the genomic diversity among M. bovis isolates causing disease in different animal host species from various locations in South Africa. M. bovis strains analyzed in this study are geographic rather than host species-specific. The clonal expansion of M. bovis in the KNP highlights the effect of an introduction of a transmissible infectious disease leading to a rising epidemic in wildlife, and emphasizes the importance of disease control and movement restriction of species that serve as disease reservoirs. In conclusion, the point source introduction of a single M. bovis strain type in the KNP ecosystem lead to an M. bovis outbreak in this area that affects various host species and poses an infection risk in neighboring rural communities where HIV prevalence is high.

The Kinetics of the Humoral and Interferon-Gamma Immune Responses to Experimental Mycobacterium bovis Infection in the White Rhinoceros (Ceratotherium simum).

Mycobacterium bovis is the cause of tuberculosis (TB) in a wide range of species, including white rhinoceroses (Ceratotherium simum). Control of the disease relies on the indirect detection of infection by measuring pathogen-specific responses of the host. These are poorly described in the white rhinoceros and this study aimed to characterize the kinetics of immune responses to M. bovis infection in this species. Three white rhinoceroses were infected with M. bovis and their immune sensitization to this pathogen was measured monthly for 20 months. Cell-mediated immunity was characterized in whole blood samples as the differential release of interferon-gamma in response to bovine purified protein derivative (PPDb) and avian PPD (PPDa) as well as the release of this cytokine in response to the M. bovis proteins 6 kDa early secretory antigenic target (ESAT-6)/10 kDa culture filtrate protein (CFP-10). Humoral immunity was quantified as the occurrence or the magnitude of antibody responses to the proteins ESAT-6/CFP-10, MPB83, MPB83/MPB70, and PPDb. The magnitude and duration of immune reactivity varied between individuals; however, peak responses to these antigens were detected in all animals circa 5-9 months postinfection. Hereafter, they gradually declined to low or undetectable levels. This pattern was associated with limited TB-like pathology at postmortem examination and appeared to reflect the control of M. bovis infection following the development of the adaptive immune response. Measurement of these markers could prove useful for assessing the disease status or treatment of naturally infected animals. Moreover, immune responses identified in this study might be used to detect infection; however, further studies are required to confirm their diagnostic utility.

Isolation and molecular characterization of Mycobacterium bovis causing pulmonary tuberculosis and epistaxis in a Thoroughbred horse.

BACKGROUND: Tuberculosis caused by Mycobacterium bovis (M. bovis) is very uncommon in horses worldwide. CASE PRESENTATION: In the current study, an eight-year-old male Thoroughbred in good body condition was admitted to the Equine Clinic at the Onderstepoort Veterinary Academic Hospital in 2005 due to bilateral epistaxis accompanied by coughing. Routine examinations were conducted to determine the cause of the condition. Endoscopic examination revealed the major source of the epistaxis as the trachea, whereas thoracic radiography indicated the presence of a primary pulmonary mass. M. bovis was isolated from a broncho-alveolar lavage (BAL) sample collected. The pulmonary mass reduced in size three months later following an oral administration of enrofloxacin (7.5 mg/kg PO SID). Genetic fingerprinting by spoligotyping identified the M. bovis isolate as spoligotype SB0868 strain. This M. bovis strain type was never described previously in South Africa (SA). This is the first case of M. bovis infection in a horse in SA which has been fully documented including clinical findings, isolation and genetic characterisation of the causative pathogen. CONCLUSIONS: This report indicates that horses may contract and harbour M. bovis despite their lower susceptibility compared to other domestic animals. It also suggests that the infection may be more easily contained and eliminated from the host.

WILDLIFE ON THE MOVE: A HIDDEN TUBERCULOSIS THREAT TO CONSERVATION AREAS AND GAME FARMS THROUGH INTRODUCTION OF UNTESTED ANIMALS.

In South Africa, African buffaloes ( Syncerus caffer ) are one of the wildlife maintenance hosts for bovine tuberculosis (BTB) and play a key role in the spread of the disease to other wildlife species and potentially back to cattle. We report a trace-back investigation following the diagnosis of BTB in a previously BTB-free provincial game reserve, founded in the early 1990s in the North West Province of South Africa (SA). Using the intradermal tuberculin and interferon gamma tests, we detected Mycobacterium bovis infection in captured African buffaloes intended for sale. Detection of M. bovis was confirmed by culture and PCR. Molecular typing of M. bovis isolates from three African buffaloes revealed spoligotype SB0140 and a variable number of tandem repeat genotypes which had been previously isolated from wildlife in the KwaZulu-Natal Province of SA. Diagnosis of BTB in a previously uninfected buffalo population provides evidence that the disease can be introduced into an ecosystem through the translocation of untested plains game species. We further illustrate how BTB can remain unnoticed for considerable periods of time in free-ranging wildlife populations and emphasize the need for validated diagnostic tests for application in suitable and practical monitoring programs. This is especially important for species with maintenance host potential and those in high demand at game auctions.

Mycobacterium bovis at the animal-human interface: a problem, or not?

Mycobacterium bovis is a pathogen of significant importance in livestock and a wide range of wild animal species worldwide. It is also known to cause tuberculosis disease in humans, a fact which has raised renewed concerns regarding the zoonotic risk for humans, especially those living at the animal-human interface. This review consolidates recent reports in the literature mainly on animal and zoonotic tuberculosis with an emphasis on evolution, epidemiology, treatment and diagnosis. The information presented reveals the fundamental differences in the complexity and level at which the disease affects the economy, ecosystem and human population of regions where animal tuberculosis control is achieved and regions where little or no control is implemented. In conclusion the review suggests that bovine tuberculosis has essentially been reduced to a disease of economic importance in the developed world, while low-income countries are facing a multifaceted impact which potentially affects the health of livestock, humans and ecosystems and which is likely to increase in the presence of debilitating diseases such as HIV/AIDS and other factors which negatively affect human livelihoods.

Purified compounds and extracts from Euclea species with antimycobacterial activity against Mycobacterium bovis and fast-growing mycobacteria.

Naphthoquinones and other compounds with antimycobacterial activity against Mycobacterium tuberculosis have previously been isolated from Euclea species. In this study, several constituents of Euclea natalensis and E. undulata, as well as organic extracts of the leaves, were assessed for efficacy against the zoonotic pathogen, Mycobacterium bovis. Also included in the battery of test organisms were M. bovis BCG and the fast-growing species M. smegmatis and M. fortuitum. The acetone extract of E. natalensis had potent activity against M. bovis (MIC=26 microg/ml). The naphthoquinone 7-methyljuglone was the most active compound, with an MIC as low as 1.55 microg/ml against pathogenic M. bovis. M. bovis BCG was not as susceptible to the test compounds as the pathogenic strain, but similar patterns of activity were observed between all the strains tested. M. smegmatis appeared to be a better predictor of antimycobacterial activity against pathogenic M. bovis (and M. tuberculosis), while MIC values obtained using M. fortuitum correlated well with those of M. bovis BCG.