The West Nile virus has been detected in Rockland, Mass, according to the state Department of Public Health. Though currently no human cases have been reported, mosquitoes carrying the virus have been detected in 18 additional communities, including a recent discovery in Jamaica Plain, the first case within Boston city limits this summer. The virus is typically transmitted through the bite of an infected mosquito, according to a statement issued by the Public Health Commission. Symptoms range from headaches to severe fevers, though most do not exhibit symptoms of the virus initially. People over 50 are said to be more susceptible to severe effects. State health officials have compiled a list of tips for minimizing the chances of being bitten, which can be found at www.mass.gov/dph/wnv.