Bovine tuberculosis in southern African wildlife: a multi-species host–pathogen system

Abstract

This review examines the current situation of bovine tuberculosis (bTB) in southern African savannah systems, and uses theory on multi-species host-pathogen systems to suggest possible options for future research and management. In southern Africa, the buffalo (Syncerus caffer) and the Kafue lechwe [Marsh antelope] (Kobus leche) have been found to be maintenance hosts for this disease, but the importance of other host species is becoming apparent. The role of other host species in the maintenance and spread of the disease varies, depending on the spatial distribution and resource utilization patterns of the species, disease susceptibility, transmission modes and the ecology of both host(s) and vector(s). Future research needs to identify the pathogenicity of bTB in each of the host species, and the mechanisms and rates of inter- and intra-specific transmission among different species, in order to develop multi-host models to understand the development and spread of the disease.

Dilution effect in bovine tuberculosis: risk factors for regional disease occurrence in Africa

“…Previous studies suggested that transmission becomes more frequency-dependent when local transmission is integrated together across spatial scales [37]. In BTB, although many wildlife species can become infected, most of them act as spillover or dead-end hosts, and transmit the pathogen inefficiently [3,6]. The presence of these incompetent hosts might reduce the contact rates among herds by acting as barriers to herd movement, and thus increase the threshold host density and critical community size.…”

“…As a maintenance host, African buffalo plays an important role in rspb.royalsocietypublishing.org Proc R Soc B 280: 20130624 BTB transmission. Since African buffalo can remain infected and infectious for several years and transmit the pathogen through aerosol transmission [3], this widespread species could limit the efficiency of control measures. The movements of buffalo might also facilitate the spread of the disease, though few studies investigated this issue.…”

“…Human population density was also used as a biotic predictor variable, as human population density could be considered as an indicator of trade activity [27], which has been proved to be positively related to BTB disease risk [19,20]. Also, since maintenance hosts can maintain the pathogen in the community without any other species and are able to play important roles in disease persistence, transmission and spread [3,6], we used the percentage of the area occupied by African buffalo and greater kudu as predictor variables to test the effects of these two maintenance host species. We calculated the mean cattle density (CattleD), the mean human population density (HumanD) and the percentage of the area occupied by African buffalo (Buffalo) or greater kudu (Kudu) for each administrative area.…”

“…Although control programmes have eliminated or nearly eliminated this disease from domestic animals in some developed countries, BTB is still widespread in Great Britain, Ireland, New Zealand and many developing countries, especially in Africa [3,4]. In fact, this zoonotic disease is still an important public health concern, and can cause severe economic losses due to livestock death and trade restrictions [4].…”

A review of bovine tuberculosis at the wildlife–livestock–human interface in sub-Saharan Africa

“…between buffalo and kudu [40]). Bovine TB epidemiology in wildlife is thus a complex multi-host pathogen system [88], partly driven by resource selection and spatial ecology of wild herbivores sharing common resources and by predator-prey interactions.…”