TB or Not TB
For three weeks beginning in January, about 700 workers and patients at St. Barnabas Hospital in the Bronx, including 238 infants, were exposed to tuberculosis by an infected nurse.
During that time, after the unidentified, foreign-born woman had developed a cough, she continued to report for regular shifts in the maternity ward and the nursery at the facility. When she finally reported her cough to a doctor, he noticed that she'd earlier tested positive for latent TB. A chest X-ray showed that the disease had turned infectious.
Following Centers for Disease Control and Prevention guidelines, the nurse was isolated in her home while she began a drug regimen. The hospital also notified the city's Bureau of Tuberculosis Control, which sent a team of epidemiologists into action. They marshaled months of hospital records and tried to track down every person who had crossed paths with the infectious nurse.
On March 15, when almost two months had passed since the investigation began and 271 potential victims still remained at-large, the city's Department of Health reached out to local media in an effort to track those patients down. More than 100 have come forward since then, and seven people in total have tested positive for latent tuberculosis, which they developed after being exposed to the infectious nurse.
The St. Barnabas case is reminiscent of a 2003 incident in which a nurse exposed 1,500 patients and co-workers at Bronx-Lebanon Hospital. She was also a foreign-born health care worker who had previously tested positive for latent TB. Like the nurse from St. Barnabas, she declined treatment, even though she worked with newborns. In that earlier case, the nurse showed symptoms for two months before she sought a diagnosis; only a third of those exposed were ever tracked down, and at least four infants tested positive for latent tuberculosis.
Both nurses fit an emerging profile. According to a recent report by the Bureau of Tuberculosis Control, the majority of health care workers with infectious tuberculosis are foreign- born female nurses between the ages of 35 and 54 who work in a hospital setting and have previously tested positive for latent infection.
Although the incidence of TB in New York City has declined steadily over the past decade, the percentage of cases in health care workers actually increased slightly over the same time periodfrom 3 percent at the height of the tuberculosis epidemic in the early 1990s to 4 percent in 2002, a small but significant change.
And convincing health care workers to do something about it has been one of the most difficult tasks for epidemiologists who have made tremendous progress on other fronts.
"It's a huge source of frustration," says Dr. Sonal Munsiff, an assistant health commissioner at the Bureau of Tuberculosis Control. "Especially given that they are working with some of the most vulnerable groups of people."
A nationwide nursing shortage is responsible for a large influx of foreign-born workers, many of them coming from regions of the world where TB persists in epidemic proportions.
"TB in foreign-born health care workers is increasingly likely to come from reactivation of old infections," Munsiff says, "acquired overseas, not in New York City."
And yet, not all health care workers get tested for tuberculosis when they are first hired. According to the Bureau of Tuberculosis Control, 20 percent of the 300 health care workers who contracted infectious tuberculosis between 1998 and 2002 had unknown results for the tuberculin skin test (TST) at hiring. But even those who are tested and are shown to carry the latent form of the diseasesuch as the nurses at St. Barnabas and Bronx-Lebanondon't necessarily do anything about it. About half never get treatment.
"We don't know whether those who didn't get treated were not offered the treatment, or if they were offered and refused," Munsiff says. Either way, she would like to see more initiative on the part of hospitals. "I'd like to see them really make an effort to educate their workers, before just saying, 'OK, this person is not interested.' "
Health care workers, however, know that latent tuberculosis cannot be transmitted, does not cause symptoms, and in the overwhelming majority of cases, never progresses to the infectious state.
"A lack of symptoms diminishes people's sense of urgency," Munsiff says. "And with health care workers it's worse, because they already know the odds of developing active TB are small."
On top of that, the treatment for latent tuberculosis infection is burdensome, and in rare cases can lead to serious side effects.
"Taking Isoniazid every day for nine months is a big pain," explains Neil Schluger, an epidemiology professor at Columbia University's Mailman School of Public Health. "Doctors and nurses are a great example of 'Do as I say, not as I do.' " Schluger points out that health care workers' resistance to treatment goes beyond their sense of inconvenience.
"Many of them are extremely nervous about going on Isoniazid," he says. "But in 15 years of working with it, I've never seen a case of serious side effects."
And there are other reasons why health care workers may resist treatment.
"The disease still carries a stigma," says Joseph Lurio, a Bronx-based primary care physician who worked as a TB control officer for several years. "I had a nurse once who lied about her symptoms for fear of losing her job."
But because they work with those most susceptible to infectionnewborns and people with compromised immune systemshealth care workers with latent TB present a unique threat.
"It is important that patients be able to trust their health care providers to 'do no harm,' " Timothy Sterling, a scientist at Vanderbilt University School of Medicine in Tennessee, writes in a recent edition of The New England Journal of Medicine. "All health care workers in the United States, regardless of their country of birth, must earn that trust by doing everything possible to minimize the risk to patients."
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