West Nile Virus Cases Surge: What IPs Need to Know While Public Concern Remains Low

Swarm of Mosquitoes on Green Background Disease Carriers Insect Infestation

(Adobe Stock 1609688034 by Amith)

West Nile virus (WNV) remains the leading cause of mosquito-borne illness in the continental US, and 2025 is expected to be a higher-than-average year. As of September 23, the CDC reports more than 1,100 cases across 42 states, including nearly 750 neuroinvasive cases, the severe form of the disease that affects the brain and central nervous system.

This year’s case count is already 40% higher than typical seasons, and experts point to a warming climate as a factor in lengthening mosquito activity, which usually runs through October. Colorado leads the nation with more than 220 reported cases. For infection preventionists (IPs), this upward trend underscores the importance of surveillance and patient education, even for a disease that often fades from public concern.

Low Public Concern Despite Higher Risk

Despite rising numbers, a recent Annenberg Public Policy Center (APPC) of the University of Pennsylvania surveyconducted August 5 to 18, 2025, of nearly 1,700 U.S. adults shows that only 15% of respondents are worried about contracting West Nile virus or dengue fever in the next 3 months. This figure is unchanged from last year, reflecting a persistent disconnect between risk and public perception.

“With the increasing number of West Nile virus cases and a longer mosquito season, many people need to have a greater awareness of the virus,” noted Ken Winneg, APPC’s managing director of survey research. “[They] may want to consider taking everyday precautions to protect themselves from mosquito bites and control mosquitoes in and around their homes.”

For IPs, this data underscores the ongoing need for clear and practical messaging regarding vector-borne disease prevention.

Knowledge Gaps Identified in Survey

While most adults (75%) know that West Nile virus is transmitted through mosquito bites, significant knowledge gaps remain:

• Symptoms: Nearly half (48%) of respondents are unsure what the symptoms of WNV are. Fever (45%), muscle and joint pain (41%), and headache (38%) were most frequently identified, but misconceptions persist, such as incorrectly citing dizziness (31%) as a symptom.
• Treatment: Only 22% of adults know there is no antiviral therapy for WNV or dengue.
• Repellent Use: Just 14% know not to apply repellent under clothing, and only 33% understand that sunscreen should be applied before insect repellent.

Of the respondents, 18% believe you should apply repellent before putting on clothing over treated areas. About 38% are unsure. During the day, it is essential to apply repellent and sunscreen properly; however, only 33% know to apply sunscreen first, followed by repellent. 47% are unsure, 5% incorrectly think repellent goes first, and 15% mistakenly say order doesn’t matter. Insect repellents should not be used on babies under 2 months; 54% are aware of this, 43% are unsure, and 3% incorrectly believe it is recommended.

• Product Selection: Only 19% correctly identified that CDC recommends using an EPA-registered repellent, not simply one with the highest DEET concentration.

For IPs, these findings can inform targeted education campaigns—both inside health care facilities and in community outreach efforts.

What Patients Are Doing—and Not Doing

On a positive note, 61% of adults report taking precautions to avoid mosquito bites, with most removing standing water (80%), avoiding outdoor activities at peak mosquito hours (72%), and using insect repellent (68%). However, fewer report protective clothing (57%), repairing screens (59%), or using netting (13%).

IPs can reinforce these measures during routine patient interactions, discharge planning, and seasonal awareness campaigns. Highlighting simple environmental interventions (removing standing water, repairing screens) and correct product use may be especially impactful.

The Role of IPs

Although IPs focus primarily on health care-associated infections, vector-borne diseases like West Nile can drive seasonal surges in hospitalizations, affect vulnerable populations, and create strain on health care systems. IPs can support preparedness by:

• Educating patients and staff about transmission, symptoms, and prevention.
• Collaborating with EVS teams to address standing water or entry points around facilities.
• Incorporating vector-borne disease reminders into fall infection prevention campaigns, alongside influenza and respiratory virus education.
• Correcting misconceptions about treatment and repellent use during community outreach and staff education sessions.

Conclusion

West Nile virus activity in 2025 highlights that mosquito-borne illnesses continue to be a significant public health concern in the US, even if they are not always at the forefront of patients' minds. As case numbers rise and mosquito seasons lengthen, IPs can play a critical role in bridging the awareness gap by arming patients, staff, and communities with accurate information and actionable steps to reduce exposure and prevent illness.

By translating surveillance data into targeted education and prevention strategies, IPs help protect the most vulnerable and ensure hospitals are prepared for seasonal and emerging vector-borne threats.