BALTIMORE (AP) — Public health officials are urging Maryland residents to protect themselves against mosquito bites to prevent infection with the West Nile virus.

Department of Health and Mental Hygiene says it began tracking the virus on Monday for the 2013 season. Last year, there were 47 cases reported in Maryland.

Officials say residents should avoid areas of high mosquito activity long pants, long-sleeved shirts and hats when concerned about mosquito exposure. Residents are also urged to use an EPA-registered insect repellent.

Less than one percent of those exposed to the virus will develop more severe infections. Persons over age 50 have the highest risk of developing more severe disease, as do people who are immunocompromised.

(Copyright 2013 by The Associated Press. All Rights Reserved.)