Microsporidia MB is found predominantly associated with Anopheles gambiae s.s and Anopheles coluzzii in Ghana

Abstract

A vertically transmitted microsporidian, Microsporidia MB, with the ability to disrupt Plasmodium development was reported in Anopheles arabiensis from Kenya, East Africa. To demonstrate its range of incidence, archived DNA samples from 7575 Anopheles mosquitoes collected from Ghana were screened. MB prevalence was observed at 1.8%. An. gambiae s.s constituted 87% of positive mosquitoes while the remaining were from An. coluzzii. Both sibling species had similar positivity rates (24% and 19%; p = 0.42) despite the significantly higher number of An. gambiae s.s analysed (An. gambiae s.s = 487; An. coluzzii = 94; p = 0.0005). The microsporidian was also more prevalent in emerged adults from field-collected larvae than field-caught adults (p < 0.0001) suggestive of an efficient vertical transmission and/or horizontal transfer among larvae. This is the first report of Microsporidia MB in Anopheles mosquitoes in West Africa. It indicates possible widespread among malaria vector species and warrants investigations into the symbiont's diversity across sub-Saharan Africa.

Figure 1

Map of Ghana showing study sites where mosquitoes were collected. Only the regions (6 out of 16) where the study sites are located are named in upper cases. Study sites are named in bold. Red stars depict regions where MB-positive mosquitoes were recorded. Map was created using ArcGIS v10.4.1.

Figure 2

Microsporidia positivity rate in An. gambiae s.s and An. coluzzii. Numbers within the bar plot show the total number of mosquitoes observed for each status.