Bovine tuberculosis in wildlife in Africa: Where is the source or the sink at wildlife/livestock (/human) interfaces? de Garine-Wichatitsky, M., Caron, A., Kock, R., Tschopp, R., Munyeme, M., Hofmeyr, M., Michel, A. In press in Epidemiology & Infections
Theoretical background Susceptibility, replicate, excrete Reservoir Target Host Spillback Critical community size Ashford 1997 & 2003, Haydon et al., 2002
Theoritical background Reser voir Target Host e.g. Vaccination, culling Spillback
Theoritical background Reservoir H1 H3 H2 Target Host Maintenance community Spillback
Theoritical background Susceptibility, replicate, excrete Critical community size Maintenance Community Target Host Spillback Host diversity
New Zealand case study (Nugent 2011) Brushtail Possum Cattle
New Zealand case study (Nugent 2011) Ferret Wild pig Brushtail Possum Cattle Red deer
New Zealand case study (Nugent 2011) Ferret Wild pig Brushtail Possum Cattle Under high pig and/or ferret and/or deer densities Red deer
btb in multi-host system Role of each host dependent on its population status and contact patterns with other species. Human activities will modify epidemiological processes. Two host populations can have different roles in different ecosystems
btb in cattle in Africa OIE WAHID Source Clinical btb widespread Low prevalence in extensive systems Higher prevalence in intensive systems
btb in wildlife in Africa OIE WAHID Source Only in East and Southern Africa Mostly lack of data
btb clonal complex in Africa Africa 1 Africa 2 European 1 Origin unclear except maybe for southern Africa Müller et al., 2009, Berg et al. 2011
General African context Greater Kudu?? Common Warthog Buffalo Cattle Impala?
btb in KNP Cattle Buffalo
btb in KNP Impala Greater Kudu kudu Buffalo Buffalo Common Warthog + 10 other species Lion
Spread of btb in the GLTFCA
btb in Hluhluwe Umfolozi NP 1 2 Cattle 3 Buffalo Spillback Michel et al. 2009
btb in Lochinvar NP Cattle? Kafue Lechwe Spillback Munyeme et al. 2010 & 2011
btb in East Africa Low prevalence Low prevalence Buffalo Cattle Kob In Queen Elizabeth NP Atemnedi, P., Kock, R. personal communication
btb in West & Central Africa Cattle Brushtail Buffalo Possum Spillback
btb in wildlife Africa: mechanisms summary Source population initially in cattle Once btb is introduced in a maintenance wildlife pop (spillover from cattle) wildlife can act as maintenance host (buffalo, lechwe) But so far no spillback from wildlife to domestic cattle has been documented Environmental conditions are important determine how much the pathogen can persist in the environment Regional differences can be observed due to wildlife host abundance and the type of wildlife/livestock interface. Lack of data due to absence of surveillance in wildlife in entire regions.
Maintenance community: Gaps in knowledge Kudu Spatial spread 1) Buffalo cattle Wart hog Kudu 2) Buffalo Wart hog cattle 3) Buffalo cattle
Probability Wildlife/livestock interfaces Miguel et al., 2013. Wildlife-livestock contacts: frequency of interactions and foot-andmouth disease dynamic in cattle populations at the periphery of Transfrontier Conservation Areas in Southern Africa. Ecosphere, in press. Hwange NP & Dete Serological Gonarezhou INCIDENCE NP & Malipati Kruger NP & Serological Pesvi REVERSION Home Ranges UD cummulatives frequencies (%) Buffalo Cattle Contact Water pan City River bed National park Communal area W/L Contacts Index of contacts with buffalo + Asymmetry in the W/L interfaces Caron et al. 2013, Epidemiology & Infections
btb at the W/L/Human interface Cattle 0-5% of TB cases due to btb Human (HIV+) No data Wildlife
Implications Lack of knowledge about wildlife maintenance community in Africa Lack of tools to control wildlife (e.g. vaccination) Difficulty to control btb in wildlife Need to focus on understanding and managing the wildlife/livestock interface
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New Zealand case study (Nugent 2011) Wild pig Brushtail possum Possum Cattle Maintenance community
New Zealand case study (Nugent 2011) Red deer Longer life span Spillback Brushtail possum Possum Time lag Brushtail Possum Temporal vector
New Zealand case study (Nugent 2011) Wild pig Larger home range Dispersal by hunters Spatial Spillback Brushtail Possum Brushtail Possum Spatial spread of the disease