West Nile virus has popped up in mosquitoes in five more Connecticut towns, signaling \u201ca major expansion of West Nile virus activity in the state,\u201d said Dr. Philip Armstrong, medical entomologist at the Connecticut Agricultural Experiment Station. On Wednesday, the station, which is based in New Haven, announced that West Nile had been detected in mosquitoes trapped and tested in Darien, Stamford, Greenwich, New Haven and Waterford. Previously, virus-carrying mosquitoes had only been found in two communities, Milford and South Windsor. Armstrong said the bump in West Nile activity is expected, as it typically increases sharply in late July or early August and continues through September. \u201cWe expect to see West Nile virus to continue to amplify in the mosquito population in the weeks ahead as is typical for this time of year,\u201d he said. \u201cWe ask residents to take common sense precautions against mosquito bites. These include wearing mosquito repellent and covering up when outside for long periods of time or when mosquitoes are active.\u201d Every year, starting in June, the state traps and tests mosquitoes for a variety of illnesses that can cause disease in people. These include West Nile virus, Eastern Equine Encephalitis virus and Jamestown Canyon virus. No Eastern Equine Encephalitis has yet been detected in the state, though Jamestown Canyon virus has been detected in mosquitoes in nine communities, including New Haven, North Haven and Shelton. Jamestown Canyon virus is an emerging infectious disease that was first detected in Colorado in 1961. Like West Nile and other mosquito-borne illness, Jamestown Canyon causes mild, flu-like symptoms in most people, but can lead to more serious illnesses, such as meningitis and encephalitis. West Nile is typically the main cause of mosquito-borne illness in this region since it was first introduced into the New York City area in 1999. Last year, West Nile was detected in 143 mosquito pools from 21 towns in Fairfield, Hartford and New Haven counties and there were eight confirmed human cases of West Nile infection statewide.