Undiagnosed TB among HCWs raises concern

Be vigilant to prevent active cases

A labor and delivery nurse at Northside Hospital in Atlanta went to work with active tuberculosis for about three months, exposing 37 newborns, about 160 other patients, and colleagues. Based on news reports, she was the third nurse in two years to continue to work while having active TB. One nurse in Virginia died of undiagnosed TB.

Prompt diagnosis of tuberculosis is considered the key to preventing transmission in hospitals. But it seems surprising — and even embarrassing — when the undiagnosed case is a health care worker.

Yet often, persistent cough, fever, and weight loss are ignored or explained away. Even health care workers may scarcely think of TB as a possibility.

"When TB starts, it's sort of like you just have a cold. Do we all run to the doctor when we have a cold?" says Susan M. Ray, MD, associate professor of medicine in the division of infectious diseases at Emory University School of Medicine and associate hospital epidemiologist at Grady Memorial Hospital, both in Atlanta.

Health care workers still need to be reminded that TB is not just a disease of the past, she adds. Early detection depends on their vigilance.

Employee health plays an important role in preventing that nightmare scenario of a health care worker who infects patients and co-workers. Here are some steps you can take:

•Educate health care workers about TB.

Guidelines from the Centers for Disease Control and Prevention (CDC) call for ongoing training of health care workers in the recognition, prevention, and transmission of TB, even in facilities that would transfer any identified TB patients.

CDC suggests the training include signs and symptoms; policies on isolating patients; risk factors; epidemiology in the community, country and worldwide; and infection control practices.

"We do need to improve the awareness among health care practitioners that TB, although less common than it used to be, is still very much with us," says Ken Castro, MD, assistant surgeon general of the Public Health Service and director of the Division of Tuberculosis Elimination. He notes that more than 14,000 cases of TB were diagnosed in the United States in 2004.

•Maintain a thorough TB testing program.

CDC's draft TB guidelines recommend baseline TB screening for all health care workers, but do not recommend further screening for low-risk facilities unless an exposure occurs. The TB risk assessment should be conducted at least once a year, and medium-risk facilities should maintain TB screening at least annually, the draft guidelines state.

CDC recommends two-step testing for all baseline tests, unless the health care worker has a documented positive TB screen or a documented negative screen within six months of employment.

Adequate follow-up of health care workers in the TB screening program is critical, Ray points out.

Hospitals use different policies to ensure that health care workers receive their annual screening. For example, at Grady Memorial Hospital, health care workers cannot get an updated badge allowing them access to the building unless they have received their TB skin test, she says.

"Knowing what their skin test conversion rate is among their employees is very important to being aware of whether things are going well in their hospital or not," Ray notes.

"That's a bare minimum for an employee health organization in a hospital. They need to be able to tell you that they have reasonably complete testing. They should test very close to 100% [of eligible HCWs]," she explains.

CDC also has placed an emphasis on the training of TB skin test readers. (See TST checklist.)

•Consider treating health care workers for latent tuberculosis.

If a health care worker has a positive skin test, first consider whether this is a true conversion, Castro advises. For example, if you recently changed skin test agents (Tubersol vs. Aplisol), the reaction may simply look different.

For HCWs with HIV infection, a skin test result greater than or equal to 5 mm is considered positive. For others, a baseline result or increase over baseline of greater than or equal to 10 mm is considered positive, although in low-risk settings, a cutoff of greater than or equal to 15 mm may be used, according to the CDC draft guidelines.

Health care workers tested with Quantiferon who have a positive or "conditionally positive" baseline result should be considered positive and receive a medical and diagnostic evaluation, according to the guidelines. Those changing from conditionally positive to positive in serial testing should be referred for evaluation but should not be counted as newly converted. Those who change from negative to positive in serial testing are converters, the guidelines state.

Follow up of a newly positive result should be immediate, Ray points out. "The day the PPD [skin test] is read, they should get the chest X-ray in the next five minutes," she says. "You can't be cleared to work until your chest X-ray has been looked at."

Someone with a recent conversion or with certain underlying conditions, such as diabetes, renal disease, HIV, or rheumatologic conditions that require steroid use, should be encouraged to have treatment for latent tuberculosis infection, Ray explains.

"The treatment is so effective and so well tolerated, the risk-benefit ratio is in favor of treatment," she says. "I think we should try to be very persuasive to take therapy."

Those who have had a longstanding latent infection would not be candidates for treatment unless they are immunocompromised or have certain underlying conditions that could increase their likelihood of developing TB, Castro points out.

However, they should be questioned annually at least about signs and symptoms, he says.

"We wouldn't recommend routine X-rays," Castro says. "They haven't been shown to be a way to pick up TB in the absence of a symptom screen."

Ray also reminds HCWs with positive skin tests, "if you are ill in the future and it's something that just doesn't get better when you think it should have, try to remember you had this positive skin test."

•When in doubt, consult your local health department.

CDC also is sponsoring regional training and medical consultation centers in San Francisco, Texas, Florida, and New Jersey, Castro says.

"It's our effort at a national level to make sure there's access to the desired expertise," he adds. "It is not realistic to expect that all practitioners are going to remain proficient at the diagnosis and treatment and management of TB patients, especially if they don't see them."

Editor's note: Information about TB and health care workers is available at www.cdc.gov/ncidod/dhqp/id_tb.html.