IMPERIAL COUNTY, CA — As mosquito activity increases during the warmer months, the Imperial County Public Health Department is reminding residents, visitors, and travelers to take precautions against illnesses such as dengue, West Nile virus, and St. Louis encephalitis.
 

“Mosquitoes become more active during the warmer months of the year, increasing the potential for mosquito-borne diseases,” stated Dr. Stephen Munday, Imperial County Health Officer. “The best protection is prevention. Whether at home or traveling, individuals should take steps to avoid mosquito bites and eliminate standing water whenever possible.”
 

Earlier this year, Imperial County investigated a potential dengue case that was subsequently confirmed as locally acquired following laboratory testing. According to the California Department of Public Health, most dengue cases reported in California are associated with exposure to infected mosquitoes during travel outside the state, although locally acquired cases have been identified in recent years. In 2025, California reported 213 cases of dengue: 206 related to travel outside the state and 7 of local transmission. So far in 2026, 9 cases have been registered, all imported from areas outside the state. This finding underscores that local transmission can occur and reinforces the importance of ongoing surveillance, control efforts, and prevention measures.
 

The public should be aware of the signs and symptoms associated with mosquito-borne diseases and seek medical attention if they become ill. Symptoms typically appear a few days to two weeks after being bitten by an infected mosquito.

Dengue symptoms may include fever, severe headache, pain behind the eyes, joint and muscle pain, nausea, vomiting, swollen glands, and rash. Most people recover within a week; however, severe dengue can occur and requires immediate medical attention.
West Nile virus and St. Louis encephalitis may cause symptoms such as fever, headache, nausea, vomiting, rash, body aches, and fatigue. While many individuals experience mild illness or no symptoms, severe disease affecting the nervous system can occur, particularly among older adults and immunocompromised individuals.
 

In addition to disease surveillance and monitoring efforts, mosquito control and community participation remain critical components of prevention. The Public Health Department’s Vector Control Program conducts year-round surveillance and mosquito control activities throughout Imperial County. Community members, visitors, property owners, and businesses all play an important role in preventing mosquito breeding by regularly inspecting properties and eliminating sources of standing water where mosquitoes can lay eggs.
 

“Community participation is essential to reducing mosquito populations and preventing the spread of disease,” said Jeff Lamoure, Deputy Director of Environmental Health. “By taking preventive measures and remaining vigilant, individuals can help protect themselves, their families, and their communities.”
Everyone is encouraged to take the following precautions to prevent mosquito bites and reduce mosquito breeding:

• Apply EPA-registered insect repellent when outdoors, including during day time activities.
• Wear long-sleeved shirts, long pants, and other protective clothing when possible.
• Ensure doors and windows have properly fitted screens.
• Remove standing water from containers around homes, businesses, lodging facilities, and recreational properties, including buckets, flowerpots, tires, birdbaths, pet water dishes, and other items that can collect water.
• Clean and maintain swimming pools, spas, and ornamental ponds.
• Take mosquito prevention measures when traveling to areas where dengue and other mosquito-borne diseases are present.
• Report neglected swimming pools or other significant mosquito breeding sources to local authorities.

For more information about mosquito-borne disease prevention, visit: icphd.org/vectorcontrol