Skip all navigation Skip to page navigation

DHHS Home | A-Z Site Map | Divisions | About Us | Contacts

NC Department of Health and Human Services
NC Division of Public Health
N.C. Public Health Home

Diseases & Topics

La Crosse Encephalitis

La Crosse encephalitis is a disease caused by a virus spread through the bite of infected mosquitoes, particularly the "treehole mosquito." La Crosse encephalitis virus (LACV) is one of a group of mosquito-transmitted viruses that can cause inflammation of the brain (encephalitis). La Crosse is the most common arbovirus (mosquito-borne virus) in North Carolina, occurring mostly in the western part of the state.

Symptoms of LACV infection can occur from a few days to a couple of weeks after being bitten by an infected mosquito. The symptoms include fever, headache, nausea, vomiting and tiredness. Severe disease involving encephalitis occurs most commonly in children under age 16 and is often accompanied by seizures. Coma and paralysis occur in some cases. In rare cases, long-term disability or death can result from La Crosse encephalitis. However, many people infected with LACV do not develop symptoms at all.

There is no specific treatment for LACV infection; care is based on symptoms. If you or a family member has symptoms of severe LACV disease or any symptoms causing you concern, consult a healthcare provider for proper diagnosis.

The best way to reduce your risk of infection with LACV and other mosquito-borne viruses is to prevent mosquito bites: use insect repellent, wear long sleeves, long pants and socks or even stay indoors while mosquitoes are most active. The mosquitoes that spread LACV are most active during the daytime, in spring through late fall.

In North Carolina

For Additional Information