Vector-Borne Transmission Cycle

The female mosquito is considered the most dangerous animal in the world. When they bite, female mosquitoes can pick up viruses or parasites from an animal’s blood and transmit (or vector) them to humans or other animals during subsequent bites. For instance, West Nile virus, primarily a bird virus, can also infect humans and other animals. Other viruses, such as dengue, yellow fever, and Zika, are transmitted from person to person but originate from natural (enzootic) cycles in forest-dwelling primates. Malaria, a parasitic disease, remains one of the leading causes of death in young children in parts of Africa. Inside the mosquito, viruses replicate, and parasites undergo complex life cycles to reproduce. The pathogens then migrate to the mosquito’s salivary glands, allowing them to be injected with the mosquito’s saliva into the next animal it bites. Because viruses and parasites must be highly adapted to both the mosquito and the host, only certain diseases can be transmitted by mosquitoes.