3,000 species

According to National Geographic the world’s 3,000 species of mosquitoes transmit more diseases than any other creature. There are more than 3,000 species of mosquitoes, but the members of three bear primary responsibility for the spread of human diseases. Anopheles mosquitoes are the only species known to carry malaria. They also transmit filariasis (also called elephantiasis) and encephalitis. Culex mosquitoes carry encephalitis, filariasis, and the West Nile virus. And Aedes mosquitoes, of which the voracious Asian tiger is a member, carry yellow fever, dengue, and encephalitis.

https://www.nationalgeographic.com/animals/invertebrates/group/mosquitoes/