WASHINGTON (Map, News) - An Osbourn High School student tested positive for tuberculosis, Manassas City Public Schools officials learned Tuesday, a day after about 250 people at the school were tested for the contagious bacterial infection.

Classmates, teachers and other staffers had been bracing for the news since Thursday, when school officials sent a letter home to all students saying someone in the school community had been diagnosed with a suspected case of tuberculosis.

Although Prince William Health District officials say there is little expected risk of transferring the disease in a school setting, they have briefed school personnel and students of the symptoms.

Those tested Monday were given a short questionnaire involving symptoms and a skin test.

Students will be re-evaluated today.

“The probability that tuberculosis is spread from person to person is dependent upon a number of factors, including the length of time an individual spends with an infectious individual,” Prince William Health Director Dr. Alison Ansher wrote in a letter to parents.

Tuberculosis has been a growing issue in Northern Virginia, which accounted for approximately 60 percent of the state’s new tuberculosis cases in 2006.

Between 2002 and 2006, the Virginia Department of Health reported 112 tuberculosis cases in the Prince William Health District.

The district reported a high of 31, or nearly 10 percent of Virginia’s 329 cases in 2006.

Last year, 13,293 TB cases — or 4.4 cases per 100,000 people — were reported in the U.S., a drop of 4.2 percent from 2006 and the lowest rate recorded since national reporting began in 1953.

The District of Columbia had the highest rate, with 10.2 cases per 100,000, while the median rate was 3.5 cases.

dgenz@dcexaminer.com