Mosquito borne viruses are a major cause of mortality and morbidity, especially in the developing world. As warmer weather increases the habitat for these disease vectors the problem is spreading to the developed world. A five-year study published today in Virology Journal shows for the first time the extent of mosquito-borne viruses (known as arboviruses) in diverse regions of Kenya.

The researchers surveyed almost half a million mosquitoes from varied habitats including savannah grassland, semi-arid Acacia thorn bushes, and mangrove swamps, and sequenced the genomes of the viruses they found. 83 different viruses were found, both known and unknown species that cause disease in humans and livestock. Predominant virus families were alphaviruses, flaviviruses and orthobunyaviruses; pathogenic West Nile virus, Ndumu, Sindbis, Bunyamwera, Pongola and Usutu virus were all found in diverse locations. Of particular interest was the isolation of Ngari virus, associated with hemorrhagic fever in northern Kenya in the late 1990s, from two sites in Kenya.

The authors, from United States Army Medical Research Unit, Kenya, Kenya Medical Research Institute, and the International Centre for Insect Physiology and Ecology in Nairobi, also found two previously unknown viruses, one with similarities to the newly discovered Chaoyang virus in China, and two more related to Quang Binh virus.

This study provides a hugely important resource for public health professionals in East Africa, identifying the habitat of these viruses and their insect vectors for the first time. Professor Linfa Wang, Editor-in-Chief of Virology Journal and an expert in emerging infectious diseases commented that “this important study highlights the need for on-going surveillance in animals and insect vectors, in order to prepare for potential virus outbreaks in humans.”