Evaluating the impact of targeting livestock for the prevention of human and animal trypanosomiasis, at village level, in districts newly affected with T. b. rhodesiense in Uganda

Abstract

BackgroundUganda has suffered from a series of epidemics of Human African Trypanosomiasis (HAT), a tsetse transmitted disease, also known as sleeping sickness. The area affected by acute Trypanosoma brucei rhodesiense HAT (rHAT) has been expanding, driven by importation of infected cattle into regions previously free of the disease. These regions are also affected by African Animal Trypanosomiasis (AAT) demanding a strategy for integrated disease control.MethodsIn 2008, the Public Private Partnership, Stamp Out Sleeping Sickness (SOS) administered a single dose of trypanocide to 31 486 head of cattle in 29 parishes in Dokolo and Kaberamaido districts. This study examines the impact of this intervention on the prevalence of rHAT and AAT trypanosomes in cattle from villages that had (HAT+ve) or had not (HAT-ve) experienced a recent case of rHAT. Cattle herds from 20 villages were sampled and screened by PCR, pre-intervention and 6-months post-intervention, for the presence or absence of: Trypanosoma brucei s.l.; human infective T. b. rhodesiense; Trypanosoma vivax; and Trypanosoma congolense savannah.ResultsPost-intervention, there was a significant decrease in the prevalence of T. brucei s.l. and the human infective sub-species T. b. rhodesiense in village cattle across all 20 villages. The prevalence of T. b. rhodesiense was reduced from 2.4% to 0.74% (P < 0.0001), with the intervention showing greater impact in HAT-ve villages. The number of villages containing cattle harbouring human infective parasites decreased from 15/20 to 8/20, with T. b. rhodesiense infection mainly persisting within cattle in HAT+ve villages (six/eight). The proportion of T. brucei s.l. infections identified as human infective T. b. rhodesiense decreased after the intervention from 8.3% (95% CI = 11.1–5.9%) to 4.1% (95% CI = 6.8–2.3%). Villages that had experienced a recent human case (HAT+ve villages) showed a significantly higher prevalence for AAT both pre- and post-intervention. For AAT the prevalence of T. vivax was significantly reduced from 5.9% to 0.05% post-intervention while the prevalence of T. congolense increased from 8.0% to 12.2%.ConclusionsThe intervention resulted in a significant decrease in the prevalence of T. brucei s.l., human infective T. b. rhodesiense and T. vivax infection in village cattle herds. The proportion of T. brucei s.l. that were human infective, decreased from 1:12 T. brucei s.l. infections before the intervention to 1:33 post-intervention. It is clearly more difficult to eliminate T. b. rhodesiense from cattle in villages that have experienced a human case. Evidence of elevated levels of AAT in livestock within village herds is a useful indicator of risk for rHAT in Uganda. Integrated veterinary and medical surveillance is key to successful control of zoonotic rHAT.Electronic supplementary materialThe online version of this article (doi:10.1186/s40249-016-0224-8) contains supplementary material, which is available to authorized users.

The challenging problem of disease staging in human African trypanosomiasis (sleeping sickness): a new approach to a circular question

“…gambiense, 9,10 even though some attempts have been made at controlling the threat. 11,12 The disease can be conceptualized as a complex entity, the full nature of which cannot be fully appreciated when observed from just a single perspective. This situation could be improved, were it possible to observe the disease in its entirety to facilitate a better understanding of the full situation.…”

Differential virulence ofTrypanosoma brucei rhodesienseisolates does not influence the outcome of treatment with anti-trypanosomal drugs in the mouse model

“…The sensitivity of these isolates to suramin and melarsoprol is significant since these are the drugs which are recommended by WHO (2018) to treat early and late stages of Tbr HAT respectively. On the other hand the sensitivity of the Tbr isolates to diminazene aceturate, is an indicator of the utility of these drug when administered to livestock reservoirs of Tbr isolates as practiced in disease HAT control programmes in endemic countries [40] Interestingly, however, the single cases of relapses encountered in mice infected with KETRI 2482 (very-acute virulence class), KETRI 2487 (acute virulence class) and 3926 (sub-acute virulence class) were all against the two diamidines (pentamidine or dimainazene) but not against suramin or melarsoprol (Table 3) which is consistent with clinical practice of not using these specific diamidines to treat Tbr HAT (WHO, 2018). Overall, the fact that the test isolates were all sensitive (at least 80% cure rates) to the drugs suggests there was no relationship between isolates’ virulence and their sensitivity to antitrypanosomal drugs.…”

Clinical evaluation and reproductive indices of dairy cows naturally infected with Trypanosoma vivax

“…Prophylaxis of trypanosomiasis includes breaking the vectortrypanosome-animal transmission chain (HAMILL et al, 2017). Early treatment causes the rapid transfer of mechanical transmission by insects, if this is the main mode of transmission, because parasitemia is always higher in the early stages of the disease (STEPHEN, 1986).…”