If you want to get technical, WNV belongs to the Flaviviridae family. There are approximately 70 different known types of Flaviviruses, 13 of which cause diseases in humans—you might recognize some of WNV’s cousins, which include dengue, yellow fever, and encephalitis. Flaviviruses, as you might expect, are typically transmitted through mosquitoes and ticks and hosted largely in birds. WNV pertains to the Japanese Encephalitis serocomplex, and is closely related to St. Louis Encephalitis. Tracing the roots of the first cases of WNV reported in New York City indicates that the virus probably came from Israel or the Middle East.
If we took all that scientific jargon and boiled it down into simple terms, what you really need to know is this: WNV is a virus with over 70 variations that can infect humans, birds, horses, and other mammals. Its life cycle relies on birds as vertebrae hosts and mosquitoes as vectors (organisms that transmit a pathogen). Transmission of the virus happens when mosquitoes bite infected birds and are infected themselves. The virus is stored in the mosquito’s salivary glands and is spread to new hosts when the mosquito stops for a meal.
Unfortunately, WNV seems to have established itself as a seasonal epidemic in North America. With flare ups happening every summer and continuing through the fall, and with the serious potential of the disease, WNV is not something to dismiss lightly.