Scaling up of tsetse control to eliminate Gambian sleeping sickness in northern Uganda

Hope, Andrew, Mugenyi, Albert, Esterhuizen, Johan, Tirados, Inaki ORCID: https://orcid.org/0000-0002-9771-4880, Cunningham, Lucas, Garrod, Gala, Lehane, Mike, Longbottom, Joshua, Mangwiro, TN Clement, Opiyo, Mercy, Stanton, Michelle ORCID: https://orcid.org/0000-0002-1754-4894, Torr, Steve ORCID: https://orcid.org/0000-0001-9550-4030, Vale, Glyn A., Waiswa, Charles and Selby, Richard (2022) 'Scaling up of tsetse control to eliminate Gambian sleeping sickness in northern Uganda'. PLoS Neglected Tropical Diseases, Vol 16, Issue 6, e0010222.

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Abstract

Background

Tsetse flies (Glossina) transmit Trypanosoma brucei gambiense which causes Gambian human African trypanosomiasis (gHAT) in Central and West Africa. Several countries use Tiny Targets, comprising insecticide-treated panels of material which attract and kill tsetse, as part of their national programmes to eliminate gHAT. We studied how the scale and arrangement of target deployment affected the efficacy of control.

Methodology and principal findings

Between 2012 and 2016, Tiny Targets were deployed biannually along the larger rivers of Arua, Maracha, Koboko and Yumbe districts in North West Uganda with the aim of reducing the abundance of tsetse to interrupt transmission. The extent of these deployments increased from ~250 km2 in 2012 to ~1600 km2 in 2015. The impact of Tiny Targets on tsetse populations was assessed by analysing catches of tsetse from a network of monitoring traps; sub-samples of captured tsetse were dissected to estimate their age and infection status. In addition, the condition of 780 targets (~195/district) was assessed for up to six months after deployment. In each district, mean daily catches of tsetse (G. fuscipes fuscipes) from monitoring traps declined significantly by >80% following the deployment of targets. The reduction was apparent for several kilometres on adjacent lengths of the same river but not in other rivers a kilometre or so away. Expansion of the operational area did not always produce higher levels of suppression or detectable change in the age structure or infection rates of the population, perhaps due to the failure to treat the smaller streams and/or invasion from adjacent untreated areas. The median effective life of a Tiny Target was 61 (41.8–80.2, 95% CI) days.

Conclusions

Scaling-up of tsetse control reduced the population of tsetse by >80% across the intervention area. Even better control might be achievable by tackling invasion of flies from infested areas within and outside the current intervention area. This might involve deploying more targets, especially along smaller rivers, and extending the effective life of Tiny Targets.

Item Type:	Article
Subjects:	QX Parasitology > Insects. Other Parasites > QX 505 Diptera QX Parasitology > Insects. Other Parasites > QX 600 Insect control. Tick control WC Communicable Diseases > Tropical and Parasitic Diseases > WC 705 Trypanosomiasis WC Communicable Diseases > Tropical and Parasitic Diseases > WC 765 Prevention and control
Faculty: Department:	Biological Sciences > Vector Biology Department
Digital Object Identifer (DOI):	https://doi.org/10.1371/journal.pntd.0010222
Depositing User:	Georgia Harrison
Date Deposited:	19 Jul 2022 13:07
Last Modified:	19 Jul 2022 13:07
URI:	https://archive.lstmed.ac.uk/id/eprint/20720

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