 Mosquitoes are perhaps the best known invertebrate vector and transmit a wide range of tropical diseases including malaria, dengue fever and yellow fever.Another large group of vectors are flies.Sandfly species transmit the disease leishmaniasis, by acting as vectors for protozoan "Leishmania" species, and tsetse flies transmit protozoan trypansomes ("Trypanosoma brucei gambiense" and "Trypansoma brucei rhodesiense") which cause African Trypanosomiasis (sleeping sickness).