Annenberg Public Policy Center survey shows West Nile knowledge gap in U.S. despite rising cases

A recent Annenberg Public Policy Center survey found that few Americans are worried about the threat of West Nile virus despite the growing number of cases nationwide.

The survey — which is a part of the Annenberg Science Knowledge research series — released its findings on Sept. 26. Conducted from Aug. 5 to 18, the survey showed that 15% of respondents worried that they or a family member would contract West Nile virus or dengue fever — another mosquito-borne illness — in the next three months.

According to the study, 48% of American adults were unaware of West Nile virus symptoms, though 75% knew that it is a mosquito-borne illness and 81% knew that the best defense against the illness is to avoid getting bitten.

West Nile primarily spreads through bites by mosquitoes carrying the disease. Many common symptoms overlap with signs of the flu, including fever, fatigue, headache, muscle weakness, and diarrhea.

Knowledge about the correct way to apply mosquito repellent was reportedly low. Around 14% of respondents said they knew that mosquito repellent is ineffective when under clothes, while 33% knew to allow sunscreen to dry before applying mosquito repellent.

As of September 2025, the Centers for Disease Control and Prevention reported 1,324 West Nile virus cases spanning 42 states, with 874 cases reported to be neuroinvasive. The statistic is about 40% more than cases reported by this point in previous years, making 2025 the most severe year so far for West Nile virus in the United States in the past decade. 

There is currently no vaccine or antiviral medicine against West Nile virus, which makes mosquito-related measures the most pertinent means of fighting the illness. According to the survey, few American adults knew this fact, with 17% answering that they believed an antiviral treatment is available, while 61% were unsure.

The survey is part of the Annenberg Science Knowledge survey series, a public opinion research project launched by the Annenberg Public Policy Center in 2016.