Climate, Cattle Rearing Systems and African Animal Trypanosomosis Risk in Burkina Faso

Abstract

BackgroundIn sub-Saharan countries infested by tsetse flies, African Animal Trypanosomosis (AAT) is considered as the main pathological constraint to cattle breeding. Africa has known a strong climatic change and its population was multiplied by four during the last half-century. The aim of this study was to characterize the impact of production practices and climate on tsetse occurrence and abundance, and the associated prevalence of AAT in Burkina Faso.Methodology/Principal FindingsFour sites were selected along a South-north transect of increasing aridity. The study combines parasitological and entomological surveys. For the parasitological aspect, blood samples were collected from 1,041 cattle selected through a stratified sampling procedure including location and livestock management system (long transhumance, short transhumance, sedentary). Parasitological and serological prevalence specific to livestock management systems show a gradual increase from the Sahelian to the Sudano-Guinean area (P<0.05). Livestock management system had also a significant impact on parasitological prevalence (P<0.05). Tsetse diversity, apparent densities and their infection rates overall decreased with aridity, from four species, an apparent density of 53.1 flies/trap/day and an infection rate of 13.7% to an absence at the northern edge of the transect, where the density and diversity of other biting flies were on the contrary highest (p<0.001).Conclusions/SignificanceThe climatic pressure clearly had a negative impact on tsetse abundance and AAT risk. However, the persistency of tsetse habitats along the Mouhoun river loop maintains a high risk of cyclical transmission of T. vivax. Moreover, an “epidemic mechanical livestock trypanosomosis” cycle is likely to occur in the northern site, where trypanosomes are brought in by cattle transhuming from the tsetse infested area and are locally transmitted by mechanical vectors. In Burkina Faso, the impact of tsetse thus extends to a buffer area around their distribution belt, corresponding to the herd transhumance radius.

Dynamics of tsetse natural infection rates in the Mouhoun river, Burkina Faso, in relation with environmental factors

“…The integration of the results presented here in these AAT mapping efforts would probably lead to improved accuracies of the maps, and since the densities of tsetse are relatively stable over time (k demographic strategy) (Koné et al, 2011b), it might also allow making seasonal predictions. Of course, mechanical transmission cannot be neglected (Desquesnes et al, 2009) and can lead to a risk of trypanosomosis independent from tsetse, including outside the tsetse belt (Pagabeleguem et al, 2012). Moreover, high temperature might have contradictory impacts on different factors of transmission, for example by reducing tsetse lifespan and density (Van den Bossche et al, 2010).…”

Adult blood-feeding tsetse flies, trypanosomes, microbiota and the fluctuating environment in sub-Saharan Africa

“…Thus, such high temperature may also impact unfavorably tsetse fly and trypanosome populations. Tsetse fly pupation and survival requires favorable environmental conditions, including moderate temperature (23-25 1C), high relative humidity (75-90%) with weak saturation deficit (to avoid high evaporation power) and shade (Ndegwa et al, 1992;Courtin et al, 2010;Pagabeleguem et al, 2012). Nevertheless, higher temperatures induce a more rapid blood meal digestion by the tsetse fly; consequently, the fly may feed more frequently, which can increase both the rate of trypanosome ingestion (when the fly feeds on an infected host) and transmission (when the fly have become trypanosome infected and feeds on a non trypanosome-infected host) (Terblanche et al, 2008).…”

Treating Cattle to Protect People? Impact of Footbath Insecticide Treatment on Tsetse Density in Chad

“…Considering tsetse apparent densities and serological prevalence of trypanosomes at the study sites, the risk for trypanosomoses can be considered low to medium [34,35]. Wild hosts were very scarce, tsetse densities relatively low, and their populationsfragmented, which corresponds with a typical endemic cycle for AAT [36].…”