Health officials have issued a warning Thursday about West Nile virus after a trace of the illness was detected in mosquitoes at Ferry Point Park.

In an effort to curtail the spread of the virus, the city has started spraying parks with larvicide.

People who live near Ferry Point Park blame a nearby Pepsi plant for the invasion of mosquitoes. They say water has been standing behind the facility for months, serving as a breeding ground for the insects.

A Pepsi executive says that the company is in the process of installing a draining system, which is expected to be complete by the end of July.