Modification of Anopheles gambiae distribution at high altitudes in Madagascar

In Madagascar, Anopheles gambiae has been found below altitudes of 1,000 m. We sampled An. gambiae sensu lato (sl) between 2008 and 2010 in the Central Highlands of Madagascar at altitudes over 1,200 m. The study site consists of rainforest, rainforest edge, and an open savanna biotope. Anopheles gambiae and An. arabiensis, as well as molecular forms of An. gambiae, were identified molecularly. An. gambiae accounted for 26.7% at the edge of the rainforest and 2.3% in the open savanna biotope. One specimen of this species was caught in the forest. An. arabiensis accounted for 66.3% at the edge of the rainforest and 97.7 % in the open savanna biotope. All An. gambiae adults tested belonged to the S molecular form. An. gambiae is present at high altitudes in Madagascar, with a high prevalence at the rainforest edge. Several factors, including the appearance of new favorable biotopes, recolonization after a reduction of indoor vector control, and climate change, may contribute to its distribution. The changing distribution of An. gambiae may have consequences for the distribution and incidence of malaria in the Malagasy Highlands.