Public health officials have raised alarms over the rapid spread of the invasive Anopheles stephensi mosquito across Northern Kenya, first detected in Marsabit and Turkana in 2022. The species, known for its resistance to all classes of insecticides used against adult malaria vectors, now threatens to expand into urban areas nationwide.
Researchers report that An. stephensi has been found in Mandera, Wajir, Isiolo, Samburu, and Elgeyo Marakwet, and could soon establish itself in at least 12 other counties across the Coast, Central, Eastern, and Rift Valley regions. The mosquito thrives in urban environments, breeds in water storage containers and discarded tires, and survives extreme temperatures, making it a significant challenge for malaria control.
First detected in Africa in Djibouti in 2012, An. stephensi has been linked to surges in malaria cases in Ethiopia and Kenya. Turkana County now records a malaria prevalence of 39 percent, far above the national average of six percent.
Experts warn that the mosquito’s urban adaptability may shift malaria transmission patterns in Kenya, posing a serious threat to public health and potentially reversing gains in malaria reduction. The World Health Organization notes that the species efficiently transmits both Plasmodium falciparum and P. vivax malaria parasites.