The searing heat waves hitting the state this summer have led to an increase in mosquitoes infected with West Nile virus, experts say.

According to the State Mosquito Management Program, West Nile has been identified in mosquitoes in 13 towns, including Stratford, Norwalk, Stamford, Danbury, Greenwich, Bethel, New Haven, West Haven and Newtown. So far, there have been no human cases.

This amount of disease activity this early in the season is unprecedented and directly related to the weather, said Dr. Theodore G. Andreadis, chief medical entomologist for the Connecticut Agricultural Experiment Station. "I can honestly tell you that in all the years we've been monitoring this (since 1999), this is the most activity we've seen this early in the season," Andreadis said, blaming this summer's high heat for the increase.

Dr. Randall Nelson, public health veterinarian with the Connecticut Department of Public Health, said the rise in West Nile in Connecticut isn't shocking, given what's happening on the national level. Nelson said several nearby states, including New York, New Jersey and Massachusetts, have already reported elevated levels of infected mosquitoes.

Stamford has been the community hardest hit by virus-carrying mosquitoes, as 14 groups of West Nile-positive mosquitoes have been identified in the city's Cove Island Park.

More Information

West Nile Alert For information on West Nile virus and what you can do to prevent getting bitten by mosquitoes, visit the Connecticut Mosquito Management Program website at www.ct.gov/mosquito

Unless we have a run of cool weather or a severe storm, Andreadis said West Nile activity likely won't taper off.

"I do have some concerns that if these weather conditions continue, I only see this thing amplifying to a higher level," he said.

With this much activity, Andreadis said, it's likely that there will be some human cases of West Nile this year. Last year, there were nine human cases of West Nile, and there were 11 cases in 2010. Nelson and Andreadis said the first cases don't typically surface until August.

But both said the threat of West Nile is something to be taken seriously. Though most people infected with the virus have no symptoms or mild symptoms, some people -- particularly those 50 or older -- can become seriously ill when infected.