JACKSON, MS - State officials are defending their decision to no longer require prison inmates to undergo chest X-rays to test for tuberculosis, saying current tests are more cost-effective and meet national guidelines.

Mississippi - the only state in which tuberculosis rates have fallen since 1991 - changed its testing guidelines last fall to require skin tests on all inmates, but X-rays only on those who test positive for TB or are suspected of having the disease, according to a report on public health conducted by The Clarion-Ledger of Jackson.

"An X-ray should be performed only on those inmates who raise a high level of suspicion of TB susceptibility," said Dr. Kentrell Liddell, chief medical officer for the state Department of Corrections, citing the latest federal guidelines.

The state pays Correctional Medical Services $6.82 per inmate per day to cover health services. That company suggested eliminating the X-rays because of cost overruns, and the state Health Department and MDOC agreed.

Inmates contract tuberculosis, which is often spread through coughing, more than 10 times more often than other citizens, and once prisoners are released they easily can spread the airborne disease.

Last year, a record-low 105 cases of TB were diagnosed in Mississippi - or, 3.7 per 100,000 people. That's well below the national average of 4.8.

In Georgia, a failure to detect the disease in an inmate caused it to spread to more than 250 other inmates and staff. That state requires only skin tests for initial screenings, according to the report.

A former director of the TB control program in Seattle calls the century-old skin test "not a great test."

Up to 20 percent of those with TB won't test positive with the skin test, and a study in England suggested that up to 65 percent of those who took the skin test would have received incorrect treatment had doctors relied alone on that examination.

"What the skin test doesn't pick up is the current disease at the moment," said Dr. Charles Nolan, the Seattle physician.

Officials with the Center for Disease Control recommend a more accurate, but costly, blood test which delivers immediate results. The skin test, which costs less than $1 per person, requires 48 hours for results while the blood test is more than 40 times that expensive.

Carol Pozsik, executive director of the National Tuberculosis Controllers Association, says new developments could make the blood test a more practical alternative.

"The hope in the future is we'll all be able to use it," she said.