DOVER, Del. — State officials say two mosquito-borne viruses that carry potentially serious health risks for humans have been detected in so-called sentinel chickens in Delaware for the first time this year.

Officials say West Nile virus was recently detected along the Delaware River in the Wilmington area and in west-central Kent County, with both instances confirmed by blood samples taken from the caged chickens that are used to detect the virus. Officials say they also found West Nile virus in a wild crow in northwestern New Castle County.

Eastern equine encephalitis, meanwhile, was recently detected from a sentinel chicken in southwestern New Castle County.

So far, neither virus has been found in humans or horses.

But officials warn that peak season for transmission of mosquito-borne diseases runs from about mid-August into mid-October.