California Serogroup Viruses

• Mild illness (often self-limiting): Fever, headache, nausea, vomiting, fatigue.
• Severe illness (encephalitis, more common in children): High fever, severe headache, confusion, seizures, disorientation, tremors, altered mental status, and coma.

**California Serogroup Viruses** are transmitted to humans through the bite of infected mosquitoes, not directly from person to person. Mosquitoes become infected when they feed on infected small mammals, such as squirrels, chipmunks, and other rodents, which serve as natural reservoirs and amplifying hosts for the virus. The primary mosquito vector for **La Crosse virus** is the *Aedes triseriatus* (eastern treehole mosquito).

• Use insect repellent containing DEET, picaridin, IR3535, or oil of lemon eucalyptus when outdoors.
• Wear long-sleeved shirts and long pants, especially during dawn and dusk when mosquitoes are most active.
• Eliminate standing water around homes (e.g., in flower pots, bird baths, clogged gutters) to reduce mosquito breeding sites.
• Ensure windows and doors have intact screens to prevent mosquitoes from entering living spaces.
• Avoid outdoor activities in areas with high mosquito populations during peak biting hours.