Abstract
INTRODUCTION
Human African trypanosomiasis (HAT) is a parasitic disease that can be fatal if left untreated. MSF conducted an active screening campaign for HAT, deploying mobile teams in remote areas of the Democratic Republic of Congo (DRC) between February 2018 and June 2019. We aimed to identify village-level risk factors associated with the presence of HAT cases, to better inform future targeted screening activities.
METHODS
Between Jan 2018 and June 2019, 170 villages were included in an exploratory phase of the study, with activities involving information, education and communication, population counts, collection of global positioning system coordinates, and assessment of risk factors. Risk factors were identified based on literature review and interviews with HAT experts, and included distances between village and water, presence of specific land types, tsetse flies, and hunting and fishing activities. 152 villages were included in the later active screening phase. Screening involved lymph node palpation, card agglutination test for trypanosomes (CATT) done on whole blood for all villagers, CATT dilutions, as well as parasitological testing and confirmation should patients test 1:16 CATT positive. Serological suspect cases were defined as those CATT 1:16 positive. Treatment with pentamidine was given to all suspect cases. Univariable and multivariable Poisson regression models were used to examine the association between at least one positive case in a village and risk factors.
ETHICS
This work fulfilled the exemption criteria set by the MSF Ethics Review Board (ERB) for a posteriori analyses of routinely collected clinical data, and thus did not require MSF ERB review. It was conducted with permission from Sidney Wong, Medical Director, Operational Centre Amsterdam, MSF.
RESULTS
Of 33,147 screened individuals, from a population of 41,764 (79%) in 152 villages, 46 suspect cases were diagnosed (1.4 cases per 1000). Suspect cases came from 33 villages (22%), of which nine villages (6%) had more than one suspect case. The highest incidence was in Otanga, with 5.6 suspect cases per 1000 screened population. Limited sample size prevented us from conducting a multivariable Poisson regression, and reduced power to find statistically significant effects. Incidence rate ratios (IRR) for relevant risk factors were: presence of hunters in a village (IRR 1.7; 95%CI 0.9-3.8), village screened more than 5 years ago (IRR 2.0; 95%CI 1.0–4.7), tsetse fly observed on visit (IRR 1.3; 95%CI 0.4 –3.3), and absence of forests within 1000m of village (IRR 0.2; 95%CI 0.0–1.0).
CONCLUSION
We detected small numbers of HAT suspect cases, preventing predictive algorithm development. However our data suggest that where HAT prevalence is low, active screening campaigns might not be effective; risk factors are not likely predictive enough to enable development of targeted screening programmes. Integrating passive screening into health posts and reactionary responses, when parasitological confirmed cases are detected, may be a better alternative. This will require training of medical staff, and reformed strategies within MSF.
CONFLICTS OF INTEREST
None declared.
