Mosquito bites are always a nuisance, but for some, a little bite can cause significant harm. National data shows that as of July 29, people in 23 states have been infected with West Nile virus in 2025. In Colorado, at least 11 people have been diagnosed with West Nile virus and one person has died from the mosquito-borne disease so far this year, prompting state officials to urge residents to be more aware of the virus and take precautions. Although most people will not experience serious symptoms, the state health department warns that some people may experience fever, severe fatigue, body aches, skin rash, and swollen lymph nodes — but a lesser-known symptom can arise, too: eye issues.
Each year, a handful of patients whose vision is affected by West Nile virus will come to the Sue Anschutz-Rodgers Eye Center and see a specialist like Amit Reddy, MD, an assistant professor in the University of Colorado Department of Ophthalmology who cares for patients with uveitis, which refers to inflammation in the middle layer of the eye that is caused by a variety of conditions.
“For most people, if they get West Nile virus, they may experience mild symptoms that go away on their own. But for a small percentage of people, the virus can make its way into the brain, and those seem to be the patients who have the highest risk of eye involvement,” Reddy says. “It’s still unclear exactly how the virus gets into the eye, but the neurological connection makes us suspect that it likely goes from the brain into the eye.”
Reddy sees the highest peak of West Nile cases during the late summer and early fall. Given that at least eight counties in Colorado have mosquitoes carrying West Nile virus, we recently spoke with Reddy about what people should know about this rare occurrence.
The following interview has been edited and condensed.