The Rhode Island Department of Health (RIDOH) is announcing Rhode Island’s second human case of West Nile Virus (WNV) in 2025. A person in their 50s from Providence County has tested positive for WNV. The results were confirmed by the Centers for Disease Control and Prevention (CDC) on November 3. The person’s onset of symptoms began in early October. They have since recovered. The State’s first human case of WNV of 2025 was announced on September 25.
Due to seasonally low mosquito populations, the risk of mosquito-borne disease has significantly decreased. However, until the entire state experiences a true hard frost (defined as three consecutive hours below 32 degrees), which kills adult mosquitoes, a low risk of mosquito-borne disease remains.
WNV is the leading cause of mosquito-borne disease in the continental United States and is much more prevalent than Eastern equine encephalitis (EEE) virus. Cases of WNV occur during mosquito season, which starts in the summer and continues through fall. There are no vaccines to prevent or medications to treat WNV in people. Fortunately, most people infected with WNV do not feel sick. About one in five people who are infected develop a fever and other symptoms. About one out of 150 infected people develop a serious, sometimes fatal, illness. For more information about WNV, visit health.ri.gov/wnv.
Although extremely rare in humans, EEE virus is very serious and has a much higher human mortality rate than WNV. Approximately 30% of people with EEE virus die, and many survivors have ongoing neurological problems. Unlike WNV, which is prevalent in Rhode Island every year, EEE virus risk is variable, changing from year to year. With continued trapping and testing, the Department of Environmental Management (DEM) and RIDOH will be able to assess the EEE virus risk level this mosquito season. For more information on EEE virus and ways to prevent it, visit health.ri.gov/eee.
Mosquito trapping and testing have concluded for the 2025 mosquito season. Check RIDOH’s arboviral surveillance data webpage for the mosquito trapping and testing totals for the 2025 season. Visit health.ri.gov/mosquito