Mosquito Activity During Warmer Months
In warmer seasons, mosquito populations grow in many regions of the United States. Among mosquito-borne diseases, the Zika virus remains a concern. It can cause severe birth defects like microcephaly when transmitted during pregnancy. Although large outbreaks haven’t occurred recently, some U.S. cities still face conditions that support mosquito activity.
Cities and Regions at Higher Risk
Researchers from the National Center for Atmospheric Research and NASA examined multiple data sources. They reviewed climate conditions, mosquito breeding patterns, air traffic, and regional socioeconomic factors. Their study identified U.S. cities where Zika could spread if reintroduced.
Southern and southeastern states face the greatest potential risk. Florida stands out, especially cities like Miami, Orlando, and Jacksonville. On the West Coast, risk stretches through California and up to Sacramento. In central regions, risk reaches as far north as Salt Lake City, Denver, Kansas City, St. Louis, and Louisville.
Health Agencies Support the Findings
The Centers for Disease Control and Prevention identified the same high-risk areas. Florida, Texas, Arizona, New Mexico, California, and Louisiana show environmental conditions suitable for Aedes mosquitoes, which spread the Zika virus.
Houston presents a unique concern. It receives high volumes of air traffic from countries with active Zika cases. This raises the chance that infected individuals could bring the virus to the region.
Social and Economic Conditions Affect Exposure
Income and infrastructure also affect Zika exposure risk. People living in neighborhoods without air conditioning or screened windows face greater exposure. Limited public awareness or access to mosquito control increases vulnerability. Trash and standing water in lower-income areas can also create ideal breeding conditions.
Communities with fewer resources often lack mosquito prevention campaigns or basic infrastructure improvements. This leaves residents more exposed to health threats.
Local Culture and Housing Style May Increase Risk
Living habits and building design can affect mosquito access. For example, open-air homes without air conditioning—common in cities like Key West—allow mosquitoes to enter living spaces more easily. In these places, people may spend more time outdoors or keep doors and windows open, which increases exposure.
Reported Mosquito Activity in U.S. Cities
Some cities report high mosquito activity based on pest control service data. These include Atlanta, Chicago, Washington D.C., Detroit, and New York City. Their trends match earlier mosquito risk projections based on environmental data.
Zika Update in 2025
As of 2025, the CDC reports no local Zika virus transmission in the continental United States. However, one travel-related case occurred in Hawaii in May 2025. Two more cases are under investigation. These incidents reflect ongoing risks linked to international travel, not domestic outbreaks.
Although Zika hasn’t spread locally this year, areas with Aedes mosquito populations still require monitoring. These include many Gulf Coast states and southern U.S. cities where conditions may allow future transmission.
Preventive Measures and Outlook
Communities and individuals can reduce risk through basic mosquito control. This includes using insect repellent, removing standing water, and repairing screens on doors and windows. These actions limit mosquito access to indoor spaces.
Public health agencies continue to monitor mosquito-prone areas and educate residents about prevention. Their efforts aim to stop new cases and reduce the risk of future outbreaks in vulnerable communities.