Vigo County reports 18 mosquito pools positive for West Nile; state cases also rose

Mike, a vector-control staff member for the Vigo County Health Department, told the Board of Health that county surveillance found 18 mosquito pools positive for West Nile virus after testing 104 pools this year.

The findings are part of a larger statewide uptick: "Indiana, all 92 counties had West Nile–positive pools," Mike said, reporting 803 positive pools statewide and 34 human cases in Indiana this year. He said neighboring Illinois recorded 3,964 positive pools and 119 human cases with six deaths.

Why it matters: Local positive mosquito pools indicate active transmission in the environment and raise the likelihood of human cases. Mike said the county’s dry summer likely increased Culex mosquito breeding by creating stagnant water where that species prefers to lay eggs.

Board members and staff discussed the department’s three-pronged response: surveillance, prevention and education. "We increase our larviciding and our adulticiding both," Mike said, describing targeted treatments in and around areas where positive pools were found. He added that some positive sites are not publicly accessible but are still treated to reduce mosquito populations.

Mike also described public education plans: encouraging residents to remove standing water, fix screens and use insect repellent. When asked whether there is a vaccine for West Nile virus, Mike said, "Not that I'm aware of. I wish there was." He said that fogging, treating catch basins and other vector-control measures remain the primary prevention tools.

Board members noted the county tests more continuously than some jurisdictions. Mike explained that once a county’s surveillance detects positives, other counties sometimes scale back sampling, which can affect comparative totals.

The department did not announce any changes to public services or event cancellations. Officials said they will continue surveillance and public outreach as the season progresses.