Mosquito and tsetse fly research specimens in sample tubes after being marked with fluorescent tracking powder (pink). The mosquitoes are Aedes albopictus. The tsetse flies are Glossina palpalis gambiensis. A. albopictus, native to South-East Asia and the Indian Ocean, is a vector for pathogens such as West Nile virus, yellow fever virus, dengue virus and zika virus. Tsetse flies are blood-sucking parasitic flies found in tropical Africa that transmit Trypanosoma protozoa, which cause sleeping sickness in humans.