Characterisation of the Wildlife Reservoir Community for Human and Animal Trypanosomiasis in the Luangwa Valley, Zambia

Abstract

BackgroundAnimal and human trypanosomiasis are constraints to both animal and human health in Sub-Saharan Africa, but there is little recent evidence as to how these parasites circulate in wild hosts in natural ecosystems. The Luangwa Valley in Zambia supports high densities of tsetse flies (Glossina species) and is recognised as an historical sleeping sickness focus. The objective of this study was to characterise the nature of the reservoir community for trypanosomiasis in the absence of influence from domesticated hosts.Methodology/Principal FindingsA cross-sectional survey of trypanosome prevalence in wildlife hosts was conducted in the Luangwa Valley from 2005 to 2007. Samples were collected from 418 animals and were examined for the presence of Trypanosoma brucei s.l., T. b. rhodesiense, Trypanosoma congolense and Trypanosoma vivax using molecular diagnostic techniques. The overall prevalence of infection in all species was 13.9% (95% confidence interval [CI]: 10.71–17.57%). Infection was significantly more likely to be detected in waterbuck (Kobus ellipsiprymnus) (Odds ratio [OR] = 10.5, 95% CI: 2.36–46.71), lion (Panthera leo) (OR = 5.3, 95% CI: 1.40–19.69), greater kudu (Tragelaphus strepsiceros) (OR = 4.7, 95% CI: 1.41–15.41) and bushbuck (Tragelaphus scriptus) (OR = 4.5, 95% CI: 1.51–13.56). Bushbucks are important hosts for T. brucei s.l. while the Bovidae appear the most important for T. congolense. The epidemiology of T. vivax was less clear, but parasites were detected most frequently in waterbuck. Human infective T. b. rhodesiense were identified for the first time in African buffalo (Syncerus caffer) and T. brucei s.l. in leopard (Panthera pardus). Variation in infection rates was demonstrated at species level rather than at family or sub-family level. A number of significant risk factors interact to influence infection rates in wildlife including taxonomy, habitat and blood meal preference.Conclusion and Significance Trypanosoma parasites circulate within a wide and diverse host community in this bio-diverse ecosystem. Consistent land use patterns over the last century have resulted in epidemiological stability, but this may be threatened by the recent influx of people and domesticated livestock into the mid-Luangwa Valley.

Bovine trypanosome species prevalence and farmers’ trypanosomiasis control methods in south-western Uganda

“…This parish is situated in Biharwe sub-county, very close to Lake Mburo National Park. Wildlife has been reported to be important in maintenance and spread of AAT (Anderson et al 2011).…”

“…African animal trypanosomosis (AAT) affects all domestic animals, as well as a wide range of wildlife species that serve as a reservoir of infection for both humans and domestic animals (Anderson et al 2011). In cattle, the disease is caused by Trypanosoma vivax, Trypanosoma congolense and Trypanosoma brucei brucei (Clarkson 1976;Magona, Walubengo & Odimim 2008).…”

The neglected zoonoses—the case for integrated control and advocacy

“…Zoonotic sleeping sickness Trypanosoma brucei rhodesiense causes acute sleeping sickness (Rhodesian HAT (rHAT)), and infects a range of wildlife [34] and domestic animals [35]. Cattle constitute the most important reservoir in East Africa and southern Africa [36], and are responsible for the spread of rHAT in Uganda [37,38].…”

“…Sleeping sickness can be cured if diagnosed and treated early, but most of those affected live in remote areas with poor access to healthcare services [51]. A range of wildlife can act as reservoirs of rHAT [34], but in Uganda the reservoir of infection comprises domestic cattle [35,36]. The northwards migration of infected cattle from the endemic sleeping sickness foci has resulted in a large expansion of the rHAT focus, which now borders the Trypanosoma brucei gambiense (chronic) HAT focus [38,51].…”

Geographic range of vector-borne infections and their vectors: the role of African wildlife

“…In the Luangwa Valley, Zambia, infection with trypanosomes was significantly more likely to occur in greater kudu and bushbuck than in other ruminants. Bushbuck were important reservoirs of T. brucei, while Bovidae in general appeared to be the most important reservoirs of T. congolense (70). Tsetse flies are widely distributed in sub-Saharan Africa, between 14°N and 29°S (51).…”