West Nile virus has been detected in two mosquito samples in Rhode Island. State health and environmental officials said Thursday that mosquitoes infected with the virus were collected Aug. 19 in Charlestown and South Kingstown. The mosquito sample collected in Charlestown is from a species that bites humans. As a result, officials advise anyone attending this weekend’s Rhythm and Roots music festival in Charlestown to take extra care to avoid mosquito bites. No human cases of the virus have been reported in Rhode Island this year.