Malaria remains endemic in Ghana. The use of insecticide treated bed-net (ITNs) for malaria control in the Kassena Nankana district of Ghana stated about two decades and since then its use in the area has increased 10-fold. This study determined the prevalence of malaria vectors and the intensity of malaria transmission and compared our findings to a similar study conducted a decade ago.
Cross-sectional entomological surveys were carried out using the human landing collection method from September 2010 to August 2011. Mosquitoes were identified by PCR and Sporozoite infectivity was determined by ELISA. Transmission (EIR) was then estimated as a product of Man Biting Rate and the Sporozoite Rate.
Consistent with the findings from the previous study, Anopheles gambiae s.l. was the predominant species. Molecular analysis of a subset of the A. gambiae. s.l. specimens collected showed A. gambiae s.s. was the most dominant sibling species, mainly of the M molecular forms. Biting rates were 14.3 bites per man per night (b/m/n), less than half the previously reported estimates of 36.7 b/m/n. Plasmodium falciparum sporozoite rate of 2.7% obtained for A. gambiae s.s., was significantly lower (p-value<0.001) than the previous study (7.2 %). Transmission still remains highly seasonal, with no change in the peak transmission. The overall annual EIR dropped from 418 to 139 infective bites/person/year.
Malaria transmission in KND has declined after the long use and high coverage of ITNs in the districts.
Maxwell Appawu (Noguchi) & Martin Donnelly (LSTM)
Harry Tagbor (KNUST) & Daniel Chandramohan (LSHTM)