All 21 school buildings in Bedford County, Va., were being scrubbed and sanitized Wednesday after the death of a 17-year-old high school student from a powerful drug-resistant strain of staph bacteria.

The schools, all in Bedford County, Va., were closed after students there launched a protest over unsanitary conditions Monday, using text messages and social networking sites.

The students took Bedford County Schools Superintendent James Blevins on a tour Tuesday of Staunton River High School to show him how unclean it was, in particular the sports locker rooms.

One of its students, Ashton Bonds, died Monday after being hospitalized for more than a week from Methicillin-resistant Staphylococcus aureus, or MRSA, a strain of staph bacteria that does not respond to penicillin and related antibiotics. Blevins subsequently ordered the schools closed for cleaning.

Click here to read letter sent home to parents in Bedford County (pdf).

The Centers for Disease Control and Prevention said Bond's death is not an isolated incident and that MRSA infections are a major public health problem, more widespread than previously thought.

This was underscored in a stunning report by CDC researchers published in the Journal of the American Medical Association that says MRSA infections ultimately could kill more people annually than AIDS. The report says the deadly strain killed nearly 19,000 Americans in 2005 and suggests such infections may be twice as common as previously thought, according to its lead author, Dr. R. Monina Klevens.

In recent years, so-called superbug staph infections have been spreading through schools, hospitals, prisons and athletic facilities, CDC officials said, and more than 90,000 Americans get potentially deadly infections each year from MRSA.

The bacteria often is carried on the skin and in the noses of healthy people and can be spread by skin-to-skin contact or sharing an item used by an infected person, particularly one with an open wound.

"Essentially, what has happened here is that MRSA was, at one time, pretty much confined to patients in hospitals, and these were patients that were seriously ill," said Dr. Pascal James Imperato, the former commissioner of public health for New York City. "Now we know, there’s also a community-acquired strain of MRSA. That doesn’t mean that it hasn’t always existed. It’s just that now, we have become knowledgeable about it."

The MRSA strain is believed to have evolved through several biological mechanisms, including the overuse of antibiotics, said Imperato, chairman of the Department of Preventive Medicine and community health director of the Master of Public Health program at SUNY Downstate Medical Center.

Reports surfaced Thursday showing Bonds to be one of three youths to die as a result of the disease over the past week.

The New Hampshire Union Leader reported Thursday that two others died last week including an 11-year-old in Vancleave, Miss., who died Friday, and a 4-year-old preschooler from New Hampshire.

Boscawen Elementary preschooler Catherine Bentley of Salisbury, N.H., died after the MRSA strain she contracted triggered a lethal case of pneumonia.

Michael J. Martin, superintendent of schools for SAU 46, which includes Boscawen Elementary, told the Union Leader that once they were advised of the child's illness, the district worked closely with the state department of health to make sure students were not at risk.

"Initially they said there was no reason to be concerned. Then we heard about the report of the death in Virginia, so we contacted the department of health again. They reassured us there was no change," Martin said.

Shae Kiernan, 11, was buried on Monday. Family and friends told Mississippi-based NBC15 News the little girl died of a staph infection. The funeral took place in Kiernan’s hometown of Vancleave, a small community in Jackson County, Miss.

In the majority of cases, children are at no higher risk for the infection than the general population, Imperato said. But the bacteria does thrive in locker rooms and gymnasiums, he said.

"This scenario sets up the perfect scenario for the organism to invade the skin," he said. "In this setting, you have sweat and good exposure to skin. With youths who play football or lacrosse, the skin might also be cut or scraped, making the skin more vulnerable."

The best method of prevention is staying clean. Frequent hand-washing is a good way to prevent the spread of MRSA. And youths, as well as adults, who participate in sports or any type of physical fitness program should shower immediately after.

"Good old-fashioned cleanliness serves as the best barrier to these organisms," he said. "Just washing with ordinary soap and water is enough to remove any of the organisms that may have colonized in the skin."

About one-quarter of invasive cases of staff infection involve patients in hospitals and more than half are related to the health care industry, occurring in people who recently had surgery or were on kidney dialysis, according to the CDC study.

Officials still do not know how the infections were spread that killed the three youths. Ashton Bonds played football at one time, which would have required him to use the school’s locker room and athletic facilities, but school officials said he was not playing this year.

The Associated Press contributed to this story