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.

Raquel Inocencio Da Luz,Eric Miaka,Paul Verlé,Oscar N’Lemvo Kiabanzawoko,Anja De Weggheleire,Delphin Mavinga Phanzu,Marleen Boelaert,Philippe Büscher,Epco Hasker,Guy Caljon

doi:10.1371/journal.pntd.0009407

Raquel Inocencio Da Luz, Eric Miaka + Show 8 more

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https://doi.org/10.1371/journal.pntd.0009407

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Abstract

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.

Highlights

In Western and Central Africa, Human African Trypanosomiasis (HAT), known as sleeping sickness, is caused by Trypanosoma brucei (T.b.) gambiense and transmitted by tsetse flies
The number of cases have been rapidly declining over the past years indicating that elimination of the disease as a public health problem is within reach
In contrast to the traditional approach of sending laboratory expertise to the field, we assessed an alternative approach based on the collection of dried blood samples on filter paper that were tested in a regional laboratory

Summary

Introduction

In Western and Central Africa, Human African Trypanosomiasis (HAT), known as sleeping sickness, is caused by Trypanosoma brucei (T.b.) gambiense and transmitted by tsetse flies. Clinical signs and symptoms are unspecific during the first stage and can last for several years. Neuropsychiatric symptoms such as sleep and behavioral disturbances that lead to coma and death, are characteristic of the second stage [2]. 1 case/10,000 people/year) is considered within reach [3]. Some countries have not yet met the second elimination goal, overall progress is remarkable, and this brings the goal which focuses on interruption of HAT transmission in humans by 2030 in view

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