Vector-Borne Diseases as a Climate Health Hazard
This summary is part of the NAM’s “Communicating About Climate Change and Health” project. The project aims to support health providers and other communicators in sharing actionable information with patients and the public.
Health Impacts of Vector-Borne Diseases
Vector-borne diseases are spread by insects like mosquitoes and ticks. Climate change is expanding the habitats and activity periods of these organisms, putting more people in the United States at risk for infection. Diseases of concern for U.S. populations include:
- Lyme disease. Between 1998 and 2016, the range of the blacklegged tick, which carries Lyme disease, increased from 30% to about 45% of U.S. counties–more than doubling in less than two decades. The Centers for Disease Control and Prevention estimates that about 476,000 people are treated for Lyme each year. Most cases are reported in the Northeast, Mid-Atlantic, and Upper Midwest. Symptoms include fever, rash, facial paralysis, an irregular heartbeat, and arthritis. Lyme can become chronic and lead to long-term complications.
- West Nile virus. The most common mosquito-borne disease in the United States, West Nile has been reported in all 48 contiguous U.S. states, with the Southwest, Mississippi Delta, Great Plains, and Rocky Mountain regions most at risk. Only about 1 in 5 people who contract West Nile will experience symptoms, which include fever, headache, body aches, vomiting, diarrhea, or rash. Severe and life-threatening complications affecting the central nervous system occur in about 1 in 150 cases.
- Dengue fever. The mosquito that spreads dengue fever, which previously was limited to tropical environments, has been found as far north as San Francisco and Washington, DC. Locally transmitted cases have been recorded in California, Arizona, Florida, and Texas (Sullivan et al., 2024). Just 1 out of 4 people infected with dengue will experience symptoms. Dengue causes fever, aches and pains, nausea and vomiting, and a rash. A severe version of dengue occurs in about 5% of cases and can be fatal if not promptly treated.
Case Example
The 2016 Zika Virus Outbreak in Florida
The Zika virus is primarily spread by the A. Aegypti mosquito, the same mosquito that transmits dengue and other viruses. Hospitable environmental conditions for this mosquito have expanded in the United States in recent years. Scientists have documented A. Aegypti populations remaining active even during the winter in parts of the United States, demonstrating their increasing national distribution.
In 2016, Florida reported an unprecedented 218 locally acquired cases of the Zika virus. Most people who contract Zika do not feel sick or experience only mild symptoms. However, Zika can cause severe pregnancy complications, including death of the fetus, and serious, long-term health problems for surviving children. Rarely, Zika can cause Guillain-Barre Syndrome.
Because of these risks, Florida's response to the 2016 outbreak was swift. The Florida Department of Health employed syndromic surveillance to identify and respond to Zika cases effectively. This system was crucial in detecting otherwise unreported cases, allowing for timely interventions. Containment efforts also included the use of insecticides and larvicides, both from the ground and aerially, to manage the mosquito population responsible for spreading the virus.
Other public health strategies included educating the public about preventing mosquito bites and targeting mosquito control efforts in areas where infections were confirmed. These efforts paid off, and Florida recorded only two locally acquired cases of Zika the next year.
There were significant economic and social impacts from the outbreak, including increased health care costs; productivity losses from absenteeism; expenses related to mosquito control efforts; anxiety among pregnant women; and decreased tourism. One study estimated that even a mild outbreak of Zika could cost the United States more than $183 million.
This example underlines the importance of preventive measures and surveillance for vector-borne diseases.
Steps to Protect Your Health
As is true for many climate health hazards, the effects of vector-borne diseases are not felt equally across populations in the United States. Homes that do not have air conditioning and use windows for cooling or are located near standing water are more likely to come in contact with disease-carrying mosquitoes. Installing well-fitting window screens and using safe and effective insect repellents can help to reduce the risk of mosquito exposure.
Reducing any standing water around your home or neighborhood is also a good idea, as it removes mosquitoes’ habitat for breeding. Sources of standing water could include old tires, bird baths, or clogged gutters and downspouts. Mosquitos are most active after dusk, so limiting time outdoors at night can also reduce your exposure.
For tick-borne diseases, people can protect themselves while outdoors by avoiding known tick habitats such as long grass, taking preventive measures like wearing long pants and long socks, and performing careful “tick checks” on children and adults after spending time outside. Learning more about the life cycle of ticks and how Lyme disease spreads can help people avoid infection.
Mitigation Strategies
Effective vector control at the city and county level is one of the best ways to mitigate risks from disease-carrying mosquitoes, but jurisdictions need to work together with partners in other towns and regions, as vectors do not respect jurisdictional boundaries. Establishing disease surveillance and early warning systems can ensure that residents are aware of risks and take proper precautions. Many health departments already use integrated case management, an approach that combines surveillance, case detection, response coordination, and vector control measures to effectively combat any vector borne diseases in an area. You can check with your local health department to see what their practices are.
References and Related Resources
- Climate Change Indicators: Lyme Disease (EPA, 2024)
- Climate Change Indicators: West Nile Virus (EPA, 2024)
- Climate Change and Vectorborne Diseases (Thomson and Stanberry, 2022)
- Lyme Disease Surveillance and Data (CDC, 2025)
- West Nile: Symptoms, Diagnosis, and Treatment (CDC, 2024)
- Local Mosquito-Borne Transmission of Zika Virus — Miami-Dade and Broward Counties, Florida, June–August 2016 (CDC, 2016)
- The potential economic burden of Zika in the continental United States (Lee et al., 2017)
- Ticks and Lyme Disease: Symptoms, Treatment, and Prevention (FDA, 2024)
- County-Scale Distribution of Ixodes scapularis and Ixodes pacificus (Acari: Ixodidae) in the Continental United States (Eisen et al., 2016)
- Dengue fever, once confined to the tropics, now threatens the U.S. (Sullivan et al., 2024)
DISCLAIMER: The information on this webpage is for general informational purposes only and should be not considered a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition.
This webpage summarizes available research on the health impacts of vector-borne diseases and mitigation strategies. The content was reviewed for accuracy by members of the expert committee on Communicating About Climate Change and Health. The summary is intended to help inform and stimulate discussion. It is not a report of the National Academy of Medicine or the National Academies of Sciences, Engineering, and Medicine.
Last updated April 10, 2025.
