Feasibility of a dried blood spot strategy for serological screening and surveillance to monitor elimination of Human African Trypanosomiasis in the Democratic Republic of the Congo.

In recent years, the number of reported Human African Trypanosomiasis (HAT) cases caused by Trypanosoma brucei (T.b.) gambiense has been markedly declining, and the goal of 'elimination as a public health problem' is within reach. For the next stage, i.e. interruption of HAT transmission by 2030, intensive screening and surveillance will need to be maintained, but with tools and strategies more efficiently tailored to the very low prevalence. We assessed the sequential use of ELISA and Immune Trypanolysis (ITL) on dried blood spot (DBS) samples as an alternative to the traditional HAT field testing and confirmation approach. A cross-sectional study was conducted in HAT endemic and previously endemic zones in Kongo Central province, and a non-endemic zone in Haut Katanga province in the Democratic Republic of the Congo (DRC). Door-to-door visits were performed to collect dried blood spot (DBS) samples on filter paper. ELISA/T.b. gambiense was conducted followed by ITL for those testing positive by ELISA and in a subset of ELISA negatives. In total, 11,642 participants were enrolled. Of these, 11,535 DBS were collected and stored in appropriate condition for ELISA testing. Ninety-seven DBS samples tested positive on ELISA. In the endemic zone, ELISA positivity was 1.34% (95%CI: 1.04-1.64). In the previously endemic zone and non-endemic zone, ELISA positivity was 0.34% (95% CI: 0.13-0.55) and 0.37% (95% CI: 0.15-0.60) respectively. Among the ELISA positives, only two samples had a positive ITL result, both from the endemic zone. One of those was from a former HAT patient treated in 2008 and the other from an individual who unfortunately had deceased prior to the follow-up visit. Our study showed that a surveillance strategy, based on DBS samples and centralized testing with retracing of patients if needed, is feasible in DRC. ELISA seems well suited as initial test with a similar positivity rate as traditional screening tests, but ITL remains complex. Alternatives for the latter, also analyzable on DBS, should be further explored.

An Active Follow-up Strategy for Serological Suspects of Human African Trypanosomiasis with Negative Parasitology Set up by a Health Zone Team in the Democratic Republic of Congo.

Background: The World Health Organization aims for the elimination of Human African Trypanosomiasis (HAT) as a public health problem by 2020 and for full elimination (absence of new cases) by 2030. One of strategies to achieve this is the active follow-up of all HAT serological suspects found during passive screening who have never been re-tested for parasitology. This is important because these cases can maintain HAT transmission and may be responsible for reemergence of the disease. Methods: In order to improve case finding at low cost in the targeted population, a general recall was transmitted to aparasitemic serological suspects about the availability of confirmation services at the general referral hospital. Transport was facilitated for re-testing. The initial examinations were carried out in Health Centers from Bagata Health Zone (HZ) in the Democratic Republic of the Congo between January 2017 and April 2019. This strategy of using a HZ team has not been previously documented. Results: From a total sample of 74 serological suspects listed by the health centers, 36 cases were re-examined at the general reference hospital; 19% (7/36) self-presented and 81% (29/36) were actively followed up by HZ personnel. Of those re-examined at the general reference hospital, 39% (14/36) resulted in a parasitologically confirmed case. Of the 14 people diagnosed with HAT, 14% (2/14) self-presented and the remaining 86% (12/14) were diagnosed in suspects who were actively followed up. This new strategy of facilitating transport from the villages added value by contributing to the detection of 12 HAT cases, compared to the passive approach, waiting for self-reference, which resulted in the detection of 2 new HAT cases. The cost per detected patient was 70 USD from the group of 7 suspects who self-presented for testing at the hospital and 346 USD per detected case for the group of 29 patients who were actively followed up by health zone staff. Conclusion: Targeted active follow-up of aparasitemic serological suspects by HZ teams is a cost-effective and promising approach to identifying additional cases of HAT in areas of very low prevalence, which would contribute to the HAT elimination goal set by the World Health Organization.

Passive Screening and Diagnosis of Sleeping Sickness with New Tools in Primary Health Services: An Operational Research.

INTRODUCTION: The integration of human African trypanosomiasis (HAT) activities into primary health services is gaining importance as a result of the decreasing incidence of HAT and the ongoing developments of new screening and diagnostic tools. In the Democratic Republic of Congo, this integration process faces multiple challenges. We initiated an operational research project to document drivers and bottlenecks of the process. METHODS: Three health districts piloted the integration of HAT screening and diagnosis into primary health services. We analysed the outcome indicators of this intervention and conducted in-depth interviews with health care providers, seropositives, community health workers and HD management team members. Our thematic interview guide focused on factors facilitating and impeding the integration of HAT screening. RESULTS: The study showed a HAT-RDT-positive rate of 2.2% in Yasa Bonga, 2.9% in Kongolo and 3% in Bibanga, while the proportion of reported seropositives that received confirmatory examinations was 76%, 45.6% and 68%, respectively. Qualitative analyses indicated that some seropositives were unable to access the confirmation facility. The main reasons that were given included distance, RDT rupture, lack of basic screening equipment and financial barriers (additional hospital fees not included in free treatment course), fear of lumbar puncture and the perception of HAT as a disease of supernatural origin. CONCLUSION: Passive screening using HAT RDTs in primary health services inevitably has some limitations. However, regarding the epidemiological context and some obstacles to integrated implementation, this cannot on its own be a relevant alternative to the elimination of HAT by 2020. FUNDING: We acknowledge the agency that provided financial support for this study, the Belgian Development Cooperation. The funder had no role in the study design, data collection and analysis, decision to publish or preparation of the manuscript. Philippe Mulenga received financial support thanks to a doctoral grant from the Belgian Development Cooperation under the FA4 agreement. Funding for the study and Rapid Service Fees was provided by the Epidemiology and Tropical Diseases Unit of the Institute of Tropical Medicine, Antwerp.