disease caused an estimated 198 million cases of malaria .
cdc ’s malaria program we report that during a recent period of hybridization between two major african malaria mosquitoes , anopheles gambiae and anopheles coluzzii , an island of divergence on chromosome 2 introgressed from the a. gambiae into the a. coluzzii genome and its frequency subsequently increased .
 
the research , published jan. 6 in the proceedings of the national academy of sciences , " provides convincing evidence indicating that a man - made change in the environment -- the introduction of insecticides -- has altered the evolutionary relationship between two species , in this case a breakdown in the reproductive isolation that separates them , " said lanzaro , who is director of the vector genetics laboratory
this study provides a rare example of adaptive introgression in an animal species and elucidates the dynamics of how insecticide resistance evolved in a. coluzzii .
90 % of all malaria deaths occur in africa .
the vast majority of cases in the united states are in travelers and immigrants returning from countries where malaria transmission occurs , many from sub - saharan africa and south asia .
abstract animal species fact sheet on the world malaria report 2014 malaria is an entirely preventable and treatable mosquito - borne illness .
left untreated , they may develop severe complications and die .