Maryland health officials said yesterday there has been an "alarming" outbreak of measles in the state this year, particularly in Prince George's County. Sixty-four cases of measles have been reported since the beginning of the year, 55 of them in Prince George's, health officials said.

Last year a total of 22 cases were reported in Maryland; the year before, 12.

Officials said they fear the disease could become even more widespread this summer because children are out of school and in the larger community.

Measles is contagious for two weeks, beginning four days before the appearance of symptoms, which include a fever, rash and a cough. Measles can lead to ear and eye infections and less frequently, to pneumonia, inflammation of the brain, known as encephalitis, and death. Although serious complications are rare, little can be done to prevent them once measles is contracted.

"We want the public to be aware this is a very dangerous situation," said health department spokeswoman Lynn Guttenberger. She urged parents to have their children immunized if they have not already done so.

The Centers for Disease Control in Atlanta report that the incidence of measles is rising nationally, at least partly because some parents mistakenly believe the disease has been eradicated and have neglected to immunize their children.

Also, about 5 percent of persons vaccinated may still contract measles because of "vaccination failure," Guttenberger said.

In Maryland, what so far has been labeled a "major outbreak" of measles, "feasibly could reach epidemic proportions," she said. Twelve new cases have been reported to Maryland health officials since the beginning of June. More alarming to health officials is that three of the 12 cases were in children under the age of 15 months.

Children below that age usually are not immunized against measles, making them particularly susceptible. And the disease is often more serious in small children, according to Guttenberger.

"This is a very alarming situation," she said. "Exposure to the disease up to this point seemed to be principally in older children in a school setting. Now it appears that it's spreading to a younger age group and elsewhere in the community. That makes it dangerous because we don't know ultimately where it will spread."

There have been several measles outbreaks in the Maryland suburbs this spring: 12 cases reported at the University of Maryland in College Park in mid-March, four cases at a Montgomery County high school in April and four cases at Eleanor Roosevelt High School in Prince George's in mid-May. One Roosevelt student was hospitalized, Guttenberger said.

In Prince George's, measles cases also were reported at Bowie High, Concordia Lutheran School and Riverdale and Bradbury Elementary schools.

"It's a source of concern. We usually have one or two cases of measles in the county," said Dr. Nigel Jackman, director of community health services in Prince George's.

The health department recommends that parents of children under 15 months of age avoid exposing their unvaccinated children to the disease.

Parents of children close to 15 months old, the usual recommended age for vaccination, should have their children vaccinated, Guttenberger said.

Adults born after 1956 who do not remember if they have been immunized, or who work in highly contagious environments such as day-care centers, should also be vaccinated. "It can't hurt to get another," Guttenberger said.

Vaccinations can be received at physicians offices or local health departments.