Key points
- La Crosse virus spreads to people through the bites of infected mosquitoes.
- Most people infected with the virus do not have symptoms.
- Some people may develop severe illness, most commonly children under 16 years old.
- You can reduce your risk of infection by preventing mosquito bites.
Overview
La Crosse is a disease caused by a virus spread infected mosquitoes. Most cases occur in the upper Midwestern, mid-Atlantic, and southeastern states.
Symptoms
Most people infected with the virus do not have symptoms. Initial symptoms can include fever, headache, nausea, vomiting, and fatigue. Some people may develop severe disease, including encephalitis (inflammation of the brain). Severe disease occurs most often in children under 16 years old.
How it spreads
La Crosse virus spreads to people through the bites of infected mosquitoes.
Prevention
No vaccines or medicines are available to prevent La Crosse. You can reduce your risk of infection by preventing mosquito bites.
Testing and diagnosis
See your healthcare provider if you have symptoms after being exposed to mosquitoes in an area where La Crosse virus spreads.
Treatment
No medicines are available to treat La Crosse. Antibiotics do not treat viruses. Rest, fluids, and over-the-counter pain medications may relieve some symptoms. Patients with severe disease often need to be hospitalized to receive support for breathing, staying hydrated, or reducing swelling in the brain.