Health officials are warning the public of possible exposure to a case of measles in Philadelphia and Delaware counties.

A person who is believed to have the contagious virus might have exposed others at the Please Touch Museum in Fairmount Park between 3:30 and 5 p.m. Monday, the Pennsylvania Department of Health said in a news release.

The likely infected person also visited the CVS Pharmacy at 316 E. Lancaster Ave. in Wayne between 5:30 and 8 p.m. Sunday, officials said.

Most U.S. residents are immune to measles because they either received the measles, mumps and rubella vaccine in childhood or were born before 1957 and exposed to measles during the pre-vaccine era.

The vaccine is currently given to all toddlers when they reach 12 to 15 months, and a second dose is required for Pennsylvania school students, according to the health department.

Those who received only one dose of the vaccine, rather than the recommended two, may still be at risk of infection.

Also at risk are infants too young to have been vaccinated and those who have not been revaccinated after receiving an inactivated vaccine, used from 1963 through 1967, officials said.

Symptoms of measles begin one to two weeks after exposure and include a runny nose, watery eyes, cough and a high fever.

After four days, those with measles develop a raised, red rash that spreads from the face, down the body and out to the arms and legs. The rash usually lasts four to seven days.

An infected person can spread the virus to others for four days before and four days after the onset of the rash, according to the health department.

Measles is spread through direct contact with infected nasal or throat secretions, or by touching objects contaminated with those droplets, which can remain contagious on surfaces for up to two hours.

Complications can include ear infection, diarrhea, pneumonia, inflammation of the brain and death, as well as miscarriages or premature delivery in pregnant women.

The measles, mumps and rubella vaccine can help prevent infection, if given within three days of exposure to the virus. There is no risk in getting an additional dose if one has already been received, according to the health department.

A dose of immune globulin can provide protection for up to six days after exposure, officials said.

Anyone who becomes ill with measles symptoms is advised to contact their health care provider so precautions can be taken to avoid exposing others.

Those who wish to receive the measles, mumps and rubella vaccine, or a dose of immune globulin, are asked to contact their health provider, or to call the Pennsylvania Department of Health at 1-877-PA-HEALTH.

More information about the virus is available on the department of health's website.

Contact Alex Wigglesworth at 215-854-2305 or awigglesworth@philly.com. Follow @phila_lex on Twitter.
Contact the Breaking News Desk at 215-854-2443; BreakingNewsDesk@philly.com. Follow @phillydotcom on Twitter.