Are you at Risk for Diseases Spread by Mosquitoes?

I have been following the mosquito monitoring reports from my local health department and see that West Nile Virus has recently been found in mosquitoes in my area. The prevalence of mosquito-borne illnesses in the US continues to increase as a result of rising temperatures, greater rainfall, and expanding mosquito habitats. In addition to traditional risk periods during late spring through early autumn, unusual outbreaks have occurred earlier or later in the year due to climate variability and international travel patterns.

Mosquito-borne diseases affect individuals nationwide, with certain regions facing elevated risks. Travelers to Mexico and Central or South America face high risk for mosquito-borne disease. I know we have talked about mosquito borne diseases before, but thought it was time for an update.

• West Nile Virus: West Nile virus remains the most frequently reported mosquito-borne disease in the US, with over 1,100 human cases and several deaths reported in 2023, especially in California, Arizona, Texas, Colorado, and Illinois (CDC West Nile Data). Most infections are asymptomatic, but some progress to severe neurological illness. The CDC continues to emphasize vigilance from June through October.
• Eastern Equine Encephalitis (EEE): EEE is rare but highly fatal, with sporadic outbreaks in the Northeast, Southeast, and Midwest, particularly near freshwater swamps. The CDC notes a mortality rate of approximately 30% among symptomatic cases, with survivors sometimes experiencing long-term neurological complications.
• Dengue: Dengue cases have surged in California, Florida, Puerto Rico, and Texas, with Puerto Rico declaring a public health emergency in March 2024. Millions of people got sick during recent dengue outbreaks in the Americas as a whole. The US sees hundreds of locally acquired dengue cases each year, and many more in recent travelers. Symptoms include high fever, severe muscle and joint pain, rash, and, in rare cases, life-threatening complications.
• Malaria: The CDC helped eliminate malaria in the US in the early 1950s. After decades without local transmission, the US saw several locally acquired malaria cases in Florida, Texas, Maryland, and Arkansas since 2022. Early detection and prompt treatment remain critical due to potential severity.
• Zika Virus: While no locally acquired cases were reported in the continental US since 2017, imported cases still occur, and the mosquito species capable of spreading Zika remain present, especially in southern states. Zika continues to pose serious risks in US territories like Puerto Rico.
• Chikungunya and Jamestown Canyon Virus: The CDC has flagged cases of chikungunya in travelers returning from the Caribbean and Central/South America, while Jamestown Canyon virus—usually mild—has seen slowly increasing reports in Northern US states.

• Use EPA-registered insect repellents containing ingredients such as DEET, picaridin, IR3535, or oil of lemon eucalyptus (Repellents: US EPA).
• Wear protective clothing – loose-fitting long sleeves, pants, socks – especially when outdoors.
• Remove standing water from items such as buckets, tires, flowerpots, birdbaths, and gutters weekly to prevent mosquito breeding.
• Ensure windows and doors have tight-fitting screens to keep mosquitoes out.
• Stay indoors at dawn and dusk, peak mosquito activity times, or use extra precautions if outdoors during these hours.
• Check your state or county health department website for current mosquito monitoring information.
• For travelers: Check the CDC’s latest maps before visiting areas with outbreaks or known transmission and pack appropriate preventive gear. Preventing Mosquito Bites While Traveling | Mosquitoes | CDC