Oklahoma mopping up long trail of TB cases
ER docs drop the ball, miss diagnosis
It took eight months and five trips to the hospital before a man in Oklahoma was finally diagnosed with TB. In his wake, he left as many as 30 secondary cases, including nine cases culture-confirmed and another 10 either primary or clinical — plus an additional ten suspect cases. The outbreak also left about one hundred people with apparent latent infection. The fact that 91% of close contacts were infected suggests the strain was exceptionally virulent (although the highest rate of infection among contacts of secondary cases is much lower, at about 30%).
Federal TB experts who arrived in Oklahoma to lend a hand haven’t yet decided whether they’ll test for virulence, adds Jon Tillinghast, MD, MPH, state TB controller.
Trying to make sense of a 600-person web of contacts has been harder than usual, too. Because many cases and contacts lived or associated closely with other, and because some cases were exceptionally mobile, investigators say they’ll have to await results from molecular fingerprinting to sort out the all the convolutions.
For all the disruption, the episode still testifies to the strength of the state’s public health infrastructure, says Tillinghast. Despite the long delay in diagnosis (caused by a collective failure on the part of a series of emergency room physicians to "think TB"), many secondary or tertiary cases were still caught, and treatment begun, before the cases progressed past the primary stage, Tillinghast points out.
Three generations in one house
The story begins with a young man with a spotty work record, a large and close-knit circle of family and friends, and a penchant for alcohol and substance abuse. Evidently it was October 2000 when he first fell sick in a neighboring state. Sometime last January he arrived in Oklahoma. His arrival marked the start of a slow trek across the southwestern part of the state, as he criss-crossed his way among three towns in three counties over a period of about eight months.
The first house where the man settled in Oklahoma was home to three generations of a family, among them five adults and five children. Other actors in that first tableau included a girlfriend with three children, and two female acquaintances, each with her own child.
During the four months’ time the index case spent in the first house, he visited emergency rooms in two hospitals on four occasions, where he got a chest X-ray and a prescription for an antibiotic. "On the basis of that first chest X-ray alone, I’d have put him into isolation and started collecting sputums," says Tillinghast.
Unfortunately, that’s not what happened; instead, the young man was referred to a pulmonologist. He made contact with the specialist, but decided not to make an appointment once he found out how much it would cost. "If he’d been referred to a public health clinic and we’d gotten to him at that point, we’d have prevented four-fifths of the cases, plus saved ourselves a heck of a lot of work," Tillinghast says with a sigh.
Consequently, the matriarch of the first household and her daughter got active TB. So did the girlfriend and her three children, all of whom contracted primary disease, as did the child of one of the two female friends.
The second female friend, found to be infected by investigators in the first go-round of contact investigations, failed to take preventive medication that was prescribed. She went on to develop cavitary, smear-positive TB, and infected her own child, who also developed primary disease with hilar adenopathy, says Tillinghast. Until RFLP data become available, no one can say for sure who in that web of contacts infected whom, but all cases have clear links to the index case, except for the child of the female friend who failed to complete preventive therapy, Tillinghast says.
The young man’s next stop was another house in a second county, where he stayed for a week or two, making forays back to the first house. Both occupants of the second house developed active disease.
A county jail with no ventilation
By May, the index case had relocated to a third house, where his grandmother lived. The grandmother, who had previously been infected, did not develop the disease and remains in good health. Between the spring day he arrived at his grandmother’s house and the first day of August (when he was diagnosed), he took a job as a waiter in a restaurant and spent three weeks in a small county jail. At the restaurant, five of 17 contacts tested were latently infected, and investigators turned up one more active case. At the jail, thanks to lack of ventilation and other mitigating environmental factors, things were considerably worse. Of 74 jail employees, 27 were infected, and one active case was found. Among 37 jail inmates evaluated, 16 appeared to be latently infected, two cases were confirmed, and one case remains suspect. Of four visitors to the jail who were tested, one was infected.
At long last, luck intervened. During the young man’s fifth visit to the third hospital, a thoughtful physician ordered him into isolation and requisitioned sputum testing. By the time he was finally diagnosed, he had cavitation and extensive infiltrates, says Tillinghast. Following several leads, authorities have so far failed to turn up the source case who infected him.
"The take-home message here is really very simple," says Tillinghast. "If you see a cough that’s lasted more than three weeks, you need to think TB."
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