Invasive Mosquitoes in California: A Public Health Concern
The “Asian tiger mosquito” (Aedes albopictus) and the “Yellow fever mosquito” (Aedes aegypti) have successfully established themselves across California. Both species can transmit diseases like Chikungunya, Dengue, Yellow fever, and Zika. In late 2023, the first two cases of locally transmitted Dengue were confirmed in Los Angeles County, highlighting the growing risk.
Current Situation in Madera County
Since its first detection in 2013, the only invasive Aedes mosquito in Madera County is Aedes aegypti. In 2019, the Madera County Department of Public Health detected one travel-related case of Dengue. While the risk of local Dengue exposure is currently minimal, the population of Aedes aegypti is expanding, increasing the risk of transmission. This mosquito is currently found in the City of Chowchilla, City of Madera, Madera Ranchos, and the newly developed communities of Riverstone and Tesoro Viejo. The Madera County Mosquito & Vector Control District is actively working to prevent mosquito-borne infections within the district.
![A female invasive Aedes aegypti mosquito (CDC 2024).](https://maderamosq.org/wp-content/uploads/2024/07/image1-1024x654.jpg)
Understanding Dengue
Dengue is a viral disease spread by Aedes mosquitoes. When these mosquitoes bite someone infected with the Dengue virus, they can then transmit the virus to others. Symptoms of Dengue can include:
- High fever
- Nausea
- Vomiting
- Rash
- Pain in the eyes, joints, or bones
Most people infected with Dengue do not show symptoms, but about 1 in 4 will experience the above symptoms. Dengue symptoms typically last from two to seven days, and most people recover within two weeks. While severe illness is possible, fatalities are very rare. There are no specific medicines for Dengue, but doctors can recommend treatments like fluids, rest, and pain or fever medication
Preventing Mosquito Bites
To protect yourself from Dengue and other mosquito-borne diseases, it’s important to avoid mosquito bites. Aedes mosquitoes are active during the day and in well-lit areas at night, needing only a small amount of water to breed. Follow these steps to reduce mosquito populations and prevent bites:
- Use mosquito repellent with DEET, IR3535, picaridin, or oil of lemon eucalyptus.
- Wear loose, long-sleeved shirts and long pants.
- Screen windows and doors to prevent mosquitoes from entering your home.
- -Screen yard drains to prevent mosquito access.
- Dump or drain standing water from buckets, plant pots, vases, old tires, gutters, and anything that may hold water for more than three days.
- Keep weeds, vines, hedges, and grass trimmed since adult mosquitoes rest in vegetation.
- Change water in pet dishes, birdbaths, and other small containers regularly.
- Properly maintain swimming pools, spas, and ponds.
- Report neglected swimming pools in your neighborhood to the Madera County Mosquito & Vector Control District.
For more information:
https://www.cdph.ca.gov/Programs/CID/DCDC/Pages/Dengue.aspx
https://www.cdc.gov/dengue/about/index.html
https://www.who.int/news-room/fact-sheets/detail/dengue-and-severe-dengue\