No evidence of Wuchereria bancrofti infection in Anopheles species after 10 years without mass drug administration: a molecular xenomonitoring study in Hauts-Bassins, Burkina Faso.

Abstract

Background: The Lymphatic Filariasis Elimination Programme was launched in Burkina Faso in 2001 aiming to eliminate the disease as a public health concern through mass drug administration (MDA). After eight years of MDA, the Hauts-Bassins region successfully passed the Transmission Assessment Survey (TAS), which led to the MDA being stopped. This study aims to assess whether parasite transmission has resurfaced in areas where MDA was stopped more than ten years ago.

Methods: A cross-sectional entomological survey was conducted in the villages of Tiebalogo and Tondogosso, in the Hauts-Bassins region. From August to December 2022, adult mosquitoes were collected using Human Landing Collection (HLC) indoor and outdoor, Window Exit Trap (WET) and Pyrethrum Spray Collection (PSC). Mosquitoes were identified morphologically. Genomic DNAs extracted from An. gambiae s.l., An. funestus, An. nili were amplified by PCR for Wuchereria bancrofti parasite detection.

Results: A total of 2688 mosquitoes were collected in both study sites, with 630 being collected in Tondogosso and 2058 in Tiebalogo. The An. gambiae s.l. was the predominant mosquitoes, with high numbers being collected in both sites. Of those collected in Tiebalogo, 1786 (86.78%) were identified as An. gambiae s.l., while 373 (59.21%) were identified in Tondogosso. The HLC method collected the greatest number of mosquitoes, followed by the PSC and WET methods. No Wuchereria bancrofti DNA was detected in any of the mosquito pools analyzed in both sites.

Conclusions: These findings provide further evidence that there is no Lymphatic Filariasis transmission occurring in Hauts-Bassin's post-TAS area. Molecular xenomonitoring of the filarial parasite which is a sensitive tool, could also serve as a complementary tool for monitoring transmission in post-MDA area and help national neglected tropical disease control program with surveillance in these areas.