As climate change reshapes the environment, mosquitoes capable of carrying deadly diseases like West Nile, Eastern equine encephalitis (EEE), and dengue are expanding their reach across the United States. These mosquito-borne diseases, once confined to specific regions, are now appearing in areas previously thought to be safe.

Since the start of the century, New York City alone has recorded nearly 500 cases of West Nile virus. Although 70-80% of infections are mild or asymptomatic, severe cases can result in permanent neurological damage. The virus is no longer isolated to East Africa and the Middle East—it’s establishing a firm hold in the U.S. In 2024, West Nile cases have been detected in 39 states, with over 1,100 mosquito pools testing positive for the virus in New York.

Even more concerning is the rise of Eastern equine encephalitis (EEE), a mosquito-borne disease with a 30% fatality rate. While still rare, EEE outbreaks are becoming more frequent, especially in the northeast. In 2019, the U.S. experienced its largest outbreak, with 38 cases. In 2024, 10 cases have already been reported, leading states like Massachusetts to implement mosquito spraying programs.

The Climate Connection:

The spread of these diseases is closely tied to climate change. Rising temperatures and increased humidity are allowing mosquitoes to thrive in new environments. Species like Aedes aegypti, known for spreading dengue, Zika, and chikungunya, are moving into northern states. Additionally, Culex coronator, another mosquito species, has spread from Louisiana to nearly all southeastern states, bringing diseases like West Nile and St. Louis encephalitis.

Experts like Chloé Lahondère of Virginia Tech warn that we are seeing more cases of individuals infected with multiple mosquito-borne diseases at once, adding another layer of complexity to disease management. The changing climate is also leading to longer mosquito breeding seasons, extending the period of risk for communities across the country.

How to Protect Yourself:

• Use Insect Repellent: Apply EPA-approved repellents containing DEET, Picaridin, or oil of lemon eucalyptus when outdoors.
• Eliminate Standing Water: Mosquitoes breed in stagnant water. Regularly empty containers like bird baths, plant saucers, and discarded plastic that collect rainwater.
• Wear Protective Clothing: Cover your skin with long sleeves and pants, especially during peak mosquito activity at dawn and dusk.
• Maintain Screens: Ensure your windows and doors have well-fitted screens to keep mosquitoes out.

Looking Ahead:

While personal protective measures are essential, experts stress that systemic solutions are needed. Researchers are exploring innovative strategies such as toxic sugar baits and genetic engineering to sterilize mosquitoes. However, addressing the root cause—climate change—is critical for long-term control. Without strong political action and public health investment, mosquito-borne diseases will continue to spread to new regions.

With dengue outbreaks already reported in California, Florida, and Arizona, and malaria cases emerging in the U.S. for the first time in 20 years, the time for action is now. As Lahondère notes, “We may not be able to create a mosquito-free future, but we can reduce the burden on human populations.”

Stay informed, take precautions, and advocate for stronger climate policies to help curb the spread of mosquito-borne diseases.