West Nile virus detected in mosquitoes from these 8 Orange County cities

- West Nile virus is the leading cause of mosquito-borne disease in the continental US. It first appeared in New York in 1999 and spread across the country. Most infected people show no symptoms, but about 1 in 5 develop fever, and roughly 1 in 150 experience serious neurological illness (encephalitis/meningitis), which can be fatal or cause lasting damage. - The virus cycles between mosquitoes (primarily Culex species) and birds. Humans and horses are "dead-end hosts" — they get sick but don't transmit the virus further. - Orange County (south of Los Angeles) has a large population and a year-round warm climate, making it a persistent hotspot for mosquito activity. Local vector control districts routinely trap and test mosquitoes to issue public warnings. - The eight cities listed (e.g., Anaheim, Santa Ana, Irvine) are among the county's most populated. Detection in mosquitoes is a signal to residents to take precautions: eliminate standing water, use repellent, and report dead birds (which can indicate active virus circulation).