Tens of thousands of genetically modified mosquitos are being released every week in Djibouti as the tiny Horn of Africa state experiments with a new weapon against an unprecedented malaria surge.

East Africa faces a deadly new threat from the arrival of Anopheles stephensi, a mosquito native to Asia and the Middle East that thrives in urban areas and is immune to insecticides.

The World Health Organization (WHO) says the species is a key factor in an unprecedented spike in malaria cases in Djibouti and Ethiopia, and has been found in six other African countries so far.