During the long Labor Day weekend, Americans will spend lots of time outdoors. Along with sunburns and poison ivy, people need to protect themselves from mosquitos that carry the West Nile Virus, which is being felt – sometimes with deadly results – in 47 states.

More than 240 cases of West Nile virus disease – including four deaths – have been reported this year – putting 2012 on track to be the worst year for the disease since 2004.