The impact of passive case detection on the transmission dynamics of gambiense Human African Trypanosomiasis.

Checchi, F., Funk, S., Chandramohan, D., Chappuis, F. and Haydon, D. T. (2018) The impact of passive case detection on the transmission dynamics of gambiense Human African Trypanosomiasis. PLoS Neglected Tropical Diseases, 12(4), e0006276. (doi: 10.1371/journal.pntd.0006276) (PMID:29624584) (PMCID:PMC5906023)

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Gambiense Human African Trypanosomiasis (HAT), or sleeping sickness, is a vector-borne disease affecting largely rural populations in Western and Central Africa. The main method for detecting and treating cases of gambiense HAT are active screening through mobile teams and passive detection through self-referral of patients to dedicated treatment centres or hospitals. Strategies based on active case finding and treatment have drastically reduced the global incidence of the disease over recent decades. However, little is known about the coverage and transmission impact of passive case detection. We used a mathematical model to analyse data from the period between active screening sessions in hundreds of villages that were monitored as part of three HAT control projects run by Médecins Sans Frontières in Southern Sudan and Uganda in the late 1990s and early 2000s. We found heterogeneity in incidence across villages, with a small minority of villages found to have much higher transmission rates and burdens than the majority. We further found that only a minority of prevalent cases in the first, haemo-lymphatic stage of the disease were detected passively (maximum likelihood estimate <30% in all three settings), whereas around 50% of patients in the second, meningo-encephalitic were detected. We estimated that passive case detection reduced transmission in affected areas by between 30 and 50%, suggesting that there is great potential value in improving rates of passive case detection. As gambiense HAT is driven towards elimination, it will be important to establish good systems of passive screening, and estimates such as the ones here will be of value in assessing the expected impact of moving from a primarily active to a more passive screening regime.

Item Type:Articles
Additional Information:This work was supported by the UK Medical Research Council (fellowship MR/K021680/1 to Sebastian Funk).
Glasgow Author(s) Enlighten ID:Haydon, Professor Daniel
Creator Roles:
Haydon, D. T.Supervision, Writing – review and editing
Authors: Checchi, F., Funk, S., Chandramohan, D., Chappuis, F., and Haydon, D. T.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
Journal Name:PLoS Neglected Tropical Diseases
Publisher:Public Library of Science
ISSN (Online):1935-2735
Copyright Holders:Copyright © 2018 Checchi et al.
First Published:First published in PLoS Neglected Tropical Diseases 12(1):e0006276
Publisher Policy:Reproduced under a Creative Commons License
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