For five days last month, Greenbelt resident Sherri Allen watched as a rash spread across her 2-year-old son, creeping from his face to his toes. Twice, when his fever rose to 105, she rushed him to the hospital.

He refused to eat, and he slept through most of three days. His lips cracked and bled.

Allen's son, Jeremy, was suffering through rubeola -- commonly known as the seven-day measles -- which recently has appeared in Maryland with a frequency that is alarming state health officials.

For Jeremy, measles was a "miserable experience," his mother said.

For state and county health workers, the recent outbreak of the disease has become "a very dangerous situation," according to state health department spokeswoman Lynn Guttenberger, who issued a public warning this month.

Sixty-four cases of measles have been confirmed in Maryland this year, 55 of them in Prince George's.

That compares to a statewide total of 22 cases last year and 12 the year before.

Thursday, a new "probable" case of measles was reported in a 16-year-old Montgomery County boy, with no known connection to the previous outbreaks.

"We don't know if this is going to be the start of something else," Guttenberger said.

While many adults think of the illness as a childhood rite of passage as common as losing baby teeth, health officials always have viewed measles as a serious, potentially fatal disease.

Earlier this year, three students at Principia College in Illinois died from complications when a measles epidemic struck the campus.

"We feel that measles is more than just a nuisance illness. It's a substantial illness," said Dr. Walter Orenstein, an official with the federal Centers for Disease Control in Atlanta.

The recent outbreak in Maryland, with 12 new cases reported in the first 12 days of June, led the state health department to issue the warning, urging parents to immunize their children.

The most common symptoms of measles are a fever, rash and a cough. But, in rare instances, measles can result in eye and ear infections, pneumonia, brain inflammation and death.

"The first thing I noticed was the fatigue," said 15-year-old Stephen Humphrey, who had one of six confirmed cases last month at Eleanor Roosevelt High School.

"The next day," he said, "I had a fever. The third day I had the rash and my eyes were irritated . . . . I was pretty uncomfortable."

Humphrey, who missed five days of school, had been immunized for measles as a small child, according to his mother. Health officials say that there is a 5 percent "vaccination failure" rate.

Sherri Allen said Jeremy was not immunized because she and her husband had moved recently and were not notified by their clinic that their son should be vaccinated at 15 months.

"If I had to do it over, he would have had his shots, because it was a miserable experience for him and it was exhausting for me," she said.

While health officials do not know why so many cases have occurred in Prince George's, they say the outbreak across the state and a recent rise nationally have been at least partially caused by the misconception that measles is no longer a threat.

"A lot of people really thought measles had been eradicated," said Guttenberger, and as a result some parents have neglected to get their children immunized.

"We have the potential here for more cases," said Dale Kay, chief of immunization for the District's Commission of Public Health.

"We're constantly urging parents to get their children immunized ," said Kay.

The only way we're ever going to whip this is to get people to believe that their children might die from this, that measles is a killer."

Kay said the District has had only one measles case reported this year, a junior high student in Southeast.

In Virginia, there have been 19 cases, five of them in Northern Virginia.

In the Maryland suburbs, there have been several outbreaks this spring, including 25 cases in College Park and five cases at St. Bartholomew's School in Bethesda, according to Guttenberger.

A breakout at Eleanor Roosevelt High in mid-May produced six confirmed cases, but there are 49 suspected cases among students and those who came in contact with them.

If confirmed, those cases would significantly raise the measles count in Prince George's.

There is also fear among officials that the disease could become more widespread this summer as children leave school and mix with other people in the community.

Despite the recent rise, the national incidence of measles has declined dramatically during the past several decades, dropping from more than 550,000 cases in 1955 to 2,534 last year.

That drop resulted primarily from use of the measles vaccine beginning in 1963 and a federally directed campaign beginning in 1978 to eliminate the disease.

Officials missed a 1982 target goal, but with persistence the disease could be eradicated in the next several years, according to the CDC's Orenstein.