Mosquitoes-borne illnesses are on the rise.
With the summer heat rising in the United States, there is growing concern about the increase in mosquito-borne infections that pose a significant threat to public health. Various diseases transmitted through mosquito bites are currently circulating, and the U.S. Centers for Disease Control and Prevention is actively monitoring and providing updated guidance to help individuals protect themselves and their loved ones.
West Nile Virus: A Persistent Threat
West Nile virus continues to be the most commonly reported mosquito-borne illness in the continental United States. The CDC is closely monitoring the disease, with 49 reported cases so far in 2025. However, cases typically peak in late summer and early fall when mosquito populations are at their highest. On average, there have been 1,000 to 3,000 cases of WNV per year in the U.S. over the past decade.
West Nile virus is prevalent across the United States and is transmitted by Culex species of mosquitoes. While most infected individuals show no symptoms, about 20% may experience fever, headache, body aches, joint pain, vomiting, diarrhea, or rash. Approximately 1 in 150 infected people, especially children and the elderly, may develop severe illness affecting the central nervous system, such as encephalitis or meningitis, which can be fatal.
Dengue Fever: A Growing Concern
A rising concern is dengue fever, which has led to multiple health alerts from the CDC in 2025. In March, the CDC issued a Health Alert Network notice indicating that dengue activity remains elevated in certain parts of the United States and globally. This follows a troubling trend where millions of people have fallen ill during recent dengue outbreaks in the Americas.
Florida remains a focal point of concern with over 100 cases reported in 2025. Nationally, the CDC has received reports of 2,396 cases. While no specific area in the United States has been declared endemic for dengue, the virus’s presence in certain regions signifies a significant shift in the country’s disease landscape.
Dengue fever is transmitted by Aedes aegypti and Aedes albopictus mosquitoes, which thrive in warm, humid environments. The disease typically starts with a sudden onset of high fever, severe headache, eye pain, muscle and joint pain, and sometimes a rash. Of particular concern is that dengue can progress to severe dengue, a critical condition that can lead to bleeding, organ failure, and death without prompt medical intervention.
Eastern Equine Encephalitis: Rare but Deadly
Eastern Equine Encephalitis is one of the most serious mosquito-borne threats, although cases are relatively uncommon. As of now, there have been no reported cases in 2025; however, there were 19 cases in 2024, including five fatalities. The CDC continues to monitor and collect data on EEE, as this virus has a mortality rate of around 30% among those who develop encephalitis.
EEE primarily circulates between birds and mosquitoes in freshwater swamps, particularly in the Atlantic and Gulf Coast states. Humans serve as accidental hosts, but when infection occurs, the consequences can be severe. The virus can cause a sudden onset of fever, chills, body aches, and, in severe cases, encephalitis leading to seizures, coma, and death.
A mother and daughter hike together and applying mosquito repellent.
Prevention: Your Best Defense
The CDC highlights that prevention is the most effective approach against mosquito-borne infections. To reduce the risk of mosquito bites, implement multiple layers of protection:
Personal Protection: Use EPA-registered insect repellents containing DEET, picaridin, or oil of lemon eucalyptus. The CDC recommends wearing loose-fitting, long-sleeved shirts and pants, especially during dawn and dusk when mosquitoes are most active. Consider using clothing and gear treated with permethrin for added protection.
Environmental Control: Eliminate stagnant water where mosquitoes breed. This includes emptying flowerpots, birdbaths, gutters, and any containers that collect rainwater. Ensure proper drainage on your property and maintain screens on windows and doors.
Abandoned plastic bowl in a vase with stagnant water inside. This creates a breeding ground for … More
Indoor Protection: Stay in places with air conditioning and window or door screens. Use bed nets if sleeping outdoors or if screened rooms are unavailable. This is especially crucial in areas where dengue transmission is occurring, such as Florida and California.
Travel Precautions: When traveling to areas with known dengue or Zika transmission, take extra precautions by using insect repellent and wearing protective clothing. Pregnant women should consult healthcare providers before traveling to affected regions.
When to Seek Medical Care
If you experience a fever or symptoms like a rash or body aches after being exposed to mosquitoes, seek medical attention promptly. Early detection and appropriate medical care can prevent complications and enhance outcomes. Serology (antibody tests) or PCR testing is available at major reference labs or public health labs.
As climate change, deforestation, and global travel continue to impact disease spread, the surge in mosquito-borne illnesses serves as a critical reminder that these infections are not limited to tropical regions but are immediate threats to public health in the United States. Taking proper precautions can reduce the risk of infection and ensure a safe and healthy rest of the summer.
