Evaluation of human and mosquito based diagnostic tools for defining endpoints for elimination of Anopheles transmitted lymphatic filariasis in Ghana

Abstract

Background: The decision to stop mass drug administration (MDA) and monitor recrudescence has to be made when endpoints for elimination of lymphatic filariasis (LF) have been achieved. Highly sensitive and specific diagnostic tools are required to do this. The main objective of this study was to determine most effective diagnostic tools for assessing interruption of LF transmission.

Methods: The presence of filarial infection in blood and mosquito samples was determined using five diagnostic tools: Brugia malayi-14 (BM14) antibody detection ELISA, Onchocerca gibsoni antigen (Og4C3) based ELISA, PCR, immunochromatography (ICT) card test and blood smear. The study was carried out in two communities in the Central Region of Ghana.

Results: OG4C3 was found to be the most sensitive test but ICT, the second most sensitive, was the most field applicable. PCR was found to be the most specific. Thirteen out of 30 pools of anopheles mosquitoes tested positive for the DNA of Wuchereria bancrofti.

Conclusions: Very low antigen prevalence in primary school children indicates that MDA is working, so children born since the intervention was put in place are not getting infected. Inclusion of xenomonitoring in monitoring the effectiveness of MDA will give a better indication as to when transmission has been interrupted especially in areas where microfilaria prevalence is lower than 1%.

Keywords: Diagnostic tools; Ghana; Lymphatic filariasis; Transmission; Xenomonitoring.