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PLoS Negl Trop Dis. 2015 Aug 12;9(8):e0003822. doi: 10.1371/journal.pntd.0003822. eCollection 2015.

Tsetse Control and Gambian Sleeping Sickness; Implications for Control Strategy.

Author information

1
Liverpool School of Tropical Medicine, Liverpool, United Kingdom.
2
Bindura University of Science Education, Department of Animal Science, Bindura, Zimbabwe.
3
Southern African Centre for Epidemiological Modelling and Analysis, University of Stellenbosch, Stellenbosch, South Africa.
4
Institut de Recherche pour le Developpement (IRD), UMR IRD-CIRAD 177 INTERTRYP CIRDES 01, Bobo-Dioulasso, Burkina Faso.
5
Liverpool School of Tropical Medicine, Liverpool, United Kingdom; Warwick Medical School, University of Warwick, Coventry, United Kingdom.

Abstract

BACKGROUND:

Gambian sleeping sickness (human African trypanosomiasis, HAT) outbreaks are brought under control by case detection and treatment although it is recognised that this typically only reaches about 75% of the population. Vector control is capable of completely interrupting HAT transmission but is not used because it is considered too expensive and difficult to organise in resource-poor settings. We conducted a full scale field trial of a refined vector control technology to determine its utility in control of Gambian HAT.

METHODS AND FINDINGS:

The major vector of Gambian HAT is the tsetse fly Glossina fuscipes which lives in the humid zone immediately adjacent to water bodies. From a series of preliminary trials we determined the number of tiny targets required to reduce G. fuscipes populations by more than 90%. Using these data for model calibration we predicted we needed a target density of 20 per linear km of river in riverine savannah to achieve >90% tsetse control. We then carried out a full scale, 500 km2 field trial covering two HAT foci in Northern Uganda to determine the efficacy of tiny targets (overall target density 5.7/km2). In 12 months, tsetse populations declined by more than 90%. As a guide we used a published HAT transmission model and calculated that a 72% reduction in tsetse population is required to stop transmission in those settings.

INTERPRETATION:

The Ugandan census suggests population density in the HAT foci is approximately 500 per km2. The estimated cost for a single round of active case detection (excluding treatment), covering 80% of the population, is US$433,333 (WHO figures). One year of vector control organised within the country, which can completely stop HAT transmission, would cost US$42,700. The case for adding this method of vector control to case detection and treatment is strong. We outline how such a component could be organised.

PMID:
26267814
PMCID:
PMC4580652
DOI:
10.1371/journal.pntd.0003822
[Indexed for MEDLINE]
Free PMC Article

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