Final answer:
The transmission of West Nile virus by mosquitoes is a form of indirect transmission, specifically vector-borne transmission.
Step-by-step explanation:
The transmission of West Nile virus (WNV) by mosquitoes is an example of biological vector transmission, which is a form of indirect transmission. Mosquitoes, specifically those from the Culex genus, act as carriers, spreading the virus from infected birds, its natural reservoir, to humans. The virus does not harm the mosquito, but it can cause symptoms ranging from mild flu-like symptoms to severe neurological disease in humans. The fact that birds can fly long distances has contributed to the rapid spread of West Nile virus since its first case in North America in 1999.