Browsing by Author "Meiring, Christina"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Investigating genome variation within a South African wild dog (Lycaon pictus) population: Towards understanding their susceptibility to Mycobacterium bovis infection
    (Stellenbosch : Stellenbosch University, 2022-04) Meiring, Christina; Miller, Michele; Moller, Marlo; Van Helden, Paul; Kinnear, Craig; Kleynhans, Leanie; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Biomedical Sciences: Molecular Biology and Human Genetics.
    ENGLISH ABSTRACT: African wild dogs (Lycaon pictus) are one of the world’s most endangered species and their survival has been impacted by human and interspecific conflict, habitat loss and disease. This keystone species is now vulnerable to genetic impoverishment which may compromise the recovery of populations and limit long-term viability. Recently, the infectious disease bovine tuberculosis (bTB), caused by Mycobacterium bovis (M. bovis), has caused mortality in wild dogs across South Africa. Mycobacterium bovis exposure levels appear to be alarmingly high in the largest African wild dog population in the country, the Kruger National Park (KNP). Currently, there is a lack of knowledge regarding the epidemiology and transmission dynamics of M. bovis in African wild dogs. Additionally, genome variation of this species, a crucial component required to support the planning of conservation strategies, has not been assessed. This study had three broad aims, (i) to characterize the molecular epidemiology of M. bovis infection in South African wild dogs, (ii) to determine whether mycobacterial shedding occurs in African wild dogs, and (iii) to assess the level of genomic diversity in KNP African wild dogs. The M. bovis strains identified in South African wild dogs were epidemiologically linked to those found in other animal hosts in shared geographical areas. A novel strain was identified in wild dogs from Hluhluwe iMfolozi Park (HiP), which showed low diversity compared to a common HiP strain. Conversely, high genetic diversity of KNP wild dog isolates was observed, indicative of multiple exposure opportunities and ongoing transmission of M. bovis. The predominant routes of M. bovis infection in wild dogs appeared to be via ingestion (of infected prey) and aerosol inhalation, as the bacterium was present in the gastrointestinal- and respiratory tract. Opportunities exist for wild dogs to share respiratory secretions, which can therefore act as an infection source. In most wild dogs, infection disseminated to multiple organ systems, and generalised disease was observed in two juvenile wild dogs, indicating that M. bovis disease may be severe in this species. However, it is unclear if the severity of the disease in African wild dogs is primarily a function of the high infection prevalence, pathogenicity of the organism or host susceptibility. The first population-wide genome data set was generated for the African wild dog, enabling the identification of genomic features consistent with a population bottleneck, based on low genome variation and excess heterozygosity. Interestingly, patterns of recent inbreeding were not detected in this population and very few closely related individuals were identified. Shallow genetic structure was observed between packs, indicating that adequate levels of gene flow were present to hamper genetic isolation. Collectively, the genomic features observed in the KNP population may not impact short- term viability, however, the low levels of genomic variation may compromise population recovery. The consequences of an emerging infectious disease on a population with low levels of genome variation may threaten the long-term viability of African wild dogs. This is critical information to consider when planning future conservation actions for this species and should be used as a framework to develop strategies that will restore genome variation and mitigate the spread of bTB.
  • Thumbnail Image
    Item
    Review of diagnostic tests for detection of mycobacterium bovis infection in South African wildlife
    (Frontiers Media S.A, 2021-01) Bernitz, Netanya; Kerr, Tanya J.; Goosen, Wynand J.; Chileshe, Josephine; Higgitt, Roxanne L.; Roos, Eduard O.; Meiring, Christina; Gumbo, Rachiel; De Waal, Candice; Clarke, Charlene; Smith, Katrin; Goldswain, Samantha; Sylvester, Taschnica T.; Kleynhans, Léanie; Dippenaar, Anzaan; Buss, Peter E.; Cooper, David V.; Lyashchenko, Konstantin P.; Warren, Robin M.; Van Helden, Paul D.; Parsons, Sven D. C.; Miller, Michele A.
    Wildlife tuberculosis is a major economic and conservation concern globally. Bovine tuberculosis (bTB), caused byMycobacteriumbovis (M. bovis), is themost common form of wildlife tuberculosis. In South Africa, to date, M. bovis infection has been detected in 24 mammalian wildlife species. The identification of M. bovis infection in wildlife species is essential to limit the spread and to control the disease in these populations, sympatric wildlife species and neighboring livestock. The detection of M. bovis-infected individuals is challenging as only severely diseased animals show clinical disease manifestations and diagnostic tools to identify infection are limited. The emergence of novel reagents and technologies to identify M. bovis infection in wildlife species are instrumental in improving the diagnosis and control of bTB. This review provides an update on the diagnostic tools to detect M. bovis infection in South African wildlife but may be a useful guide for other wildlife species.