Mosquitoes. According to the WHO, there were an estimated 247 million cases of malaria worldwide in 2021 with over 600,000 deaths, mostly in Africa. Children under 5 accounted for about 80% of all malaria deaths in the region. In addition, two other biological threats for the control of malaria were identified: drug resistance and diagnostic resistance of the parasite.Following its first detection in Djibouti in 2012, the Asian malaria mosquito Anopheles stephensi spread to the Horn of Africa (Ethiopia, Sudan, Somalia, and Eritrea) and beyond (Yemen, Nigeria, Kenya, and Ghana) at a speed unknown before for similar species.

People in households/dormitories with An. stephensi positivity had a 270% higher risk of malaria infection than those in households/dormitories where An. stephensi was not detected. In addition, two other biological threats for the control of malaria were identified: drug resistance and diagnostic resistance of the parasite. This is a very important finding. The mosquito that has spread in the Horn of Africa from Asia drove a major urban malaria outbreak in Ethiopia. An. stephensi is posing important public health concerns due to the increase in geographical presence, the capacity to persist throughout the year and to resist current insecticides, and to transmit drug and diagnostic resistant parasites.

The study found that the capacity of Anopheles stephensi to use manmade water storage containers which are abundant in rapidly expanding African urban settings, coupled with its unique ecology, behavioural plasticity and resistance to major insecticides, makes it unamenable to conventional mosquito control tools. The epidemiological characteristics of An. stephensi driven malaria can challenge the expectations for the new malaria vaccines to reduce the burden of malaria disease and deaths in Africa, the continent that was already highly hit by malaria and where successes in malaria reduction are currently stalled.