Mosquito-borne illnesses are a growing concern as summer temperatures soar across the United States. With diseases transmitted through the bite of infected mosquitoes circulating, the U.S. Centers for Disease Control and Prevention is actively monitoring the situation and providing updated guidance to help protect the public.
West Nile Virus: A Persistent Threat
West Nile virus remains the most reported mosquito-borne illness in the continental United States. With 49 cases reported in 2025 so far, the disease typically peaks in late summer and early fall when mosquito populations are at their highest. On average, there are 1,000 to 3,000 cases of West Nile virus annually in the U.S.
Transmitted by Culex species of mosquitoes, most individuals infected with WNV do not show any symptoms. However, about 20% may experience fever, headache, body aches, joint pain, and other symptoms. Severe cases affecting the central nervous system can occur in 1 out of 150 infected individuals, leading to conditions like encephalitis or meningitis, which can be fatal.
Dengue Fever: A Growing Concern
Dengue fever is becoming an increasing threat, prompting multiple CDC health alerts in 2025. With over 100 cases reported in Florida and 2,396 cases nationally, the virus poses a significant risk. Transmitted by Aedes aegypti and Aedes albopictus mosquitoes, dengue fever presents with symptoms like high fever, severe headache, muscle and joint pain, and can progress to severe dengue, a life-threatening condition.
Eastern Equine Encephalitis: Rare but Deadly
Eastern Equine Encephalitis, while rare, is a serious mosquito-borne threat with a mortality rate of approximately 30% among those who develop encephalitis. Though no cases have been reported in 2025, the virus circulates among birds and mosquitoes in freshwater swamps, primarily in the Atlantic and Gulf Coast states. Symptoms can include fever, chills, body aches, and in severe cases, encephalitis leading to coma and death.
Prevention: Your Best Defense
The CDC emphasizes prevention as the most effective strategy against mosquito-borne infections. Measures include using EPA-registered insect repellents, wearing protective clothing, eliminating standing water, staying in air-conditioned places, and taking precautions while traveling to areas with known transmission.
When to Seek Medical Care
If you develop symptoms like fever, rash, or body aches after mosquito exposure, seek medical care promptly. Early detection and proper management can prevent complications and improve outcomes. Testing is available through serology or PCR at larger reference labs or public health facilities.
In a world where climate change, deforestation, and global travel impact disease spread, the rise in mosquito-borne illnesses underscores the immediate threat to public health in the United States. By taking appropriate precautions, individuals can reduce the risk of infection and enjoy a safe and healthy summer.
