Hunting the hot case in the Big House
Source of cluster proves elusive
During late summer and early fall last year at a 2,000-bed maximum-security prison in Missouri, it looked like trouble. Big trouble, in fact, with over 70 inmates converting their skin tests within a few short months, and a half-dozen members of the medical staff converting as well.
The strange thing was that no matter how hard they tried, state TB controllers and prison medical staff couldn’t find the active case. "We looked high and low," says Vic Tomlinson, chief of Vaccine-Preventable and TB Disease Elimination at the Missouri Department of Health in Jefferson City. "We took over 300 chest X-rays. We had meetings. We spent hours — oh, I can’t tell you how many hours we spent on this thing. But we found nothing the least bit suspicious."
"We were perplexed," agrees Randee Kaiser, RN, CHP, the state Department of Correction’s assistant director for medical services. "I mean, we were testing basically everyone who was walking and talking."
Last time, 100 staff got infected
Nor was there any easy explanation — no tuberculin-reagent switch (the prison was using Tubersol, just like always), no inexperienced nursing staff misinterpreting the skin tests, nothing that seemed to account for what was happening.
There was, however, a precedent that was making everyone extremely nervous, recalls Tomlinson. The year before, another cluster of converters had turned up at a second prison in the state. After an exhaustive search, the facility had finally been locked down, with no one going in or out for an entire week, before the source case was finally nailed. By that time, however, over 100 inmates and half a dozen staff were infected and two secondary cases were identified.
With that experience still burned into everyone’s memory, "we were under a lot of pressure," says Jacinta Bunch, RN, regional infection control nurse for Correctional Medical Systems, which provides health care for the states’ 25,000-member inmate population. No one experienced the pressure to find the case more than Bunch, who had her third child in the midst of the crisis and cut her six-week maternity leave three weeks short to help find the case.
The first sign of trouble appeared in mid-summer. Inmates and staff at the prison are skin-tested each year on the date of their birth, Kaiser explains. In a typical month, there may be a single positive conversion; many months can go by with no conversions at all. But in July, of the 67 people with birthdays, there were five positive tests between 10 mm and 15 mm. Eyebrows shot up. In August, the decision was made to do mass testing. Bad news resulted: Of 545 tests, 521 were negative, and six tests fell into in the 5 mm to 9 mm range; but 17 were between 10 mm and 15 mm, and seven measured greater than 15 mm.
Back in July, the prison medical staff had begun doing what they always did with reactions greater than 10 mm, says Kaiser — symptom checks and sputum smears. They also began pulling in all inmates considered high-risk, even if they hadn’t been among the recent reactors. That meant the HIV-positives, the diabetics, those with other chronic ailments, and the elderly, where the word was redefined to mean anyone over 60. Inmates are old for their years thanks to a free-world lifestyle typically featuring intravenous drug use, alcohol abuse, and general lack of access to good health care.
Mobile population makes for many contacts
Anyone with the slightest hint of symptoms got a chest X-ray, says Kaiser. Old chest X-rays were even hauled out and carefully re-examined. Prisoners complaining of the least symptom were packed off to respiratory isolation — a task which, because the prison has no negative-pressure rooms in its medical ward, meant transporting inmates someplace else. Nurses at the facility, meanwhile, searched laboriously for links, trying to figure out whether all the reactors had spent time housed in the same area, the same work program, or the same classes. "People get moved a lot in a prison, which sometimes makes doing contact investigations a little overwhelming," notes Bunch (who also second-guessed all the skin-tests during the mass testing, just to be sure they were read correctly). "You can wind up with huge, huge numbers of contacts."
Inmates are moved not only from cell to cell, but from one of 22 correctional facilities in the state to others, she adds. Sorting through rosters going back three months, Bunch and other staffers found that most of the reactors had, in fact, spent time in a particular unit — but so had virtually everyone else in the place.
Even something as simple-sounding as symptom checks didn’t work the way it would in the free world, Kaiser notes. "Sometimes an inmate will get in trouble with his cellmate — maybe he owes him a debt or something — so he’ll come to us. These guys know the drill perfectly: I’ve lost weight! The other night I was coughing up blood! I’m having these sweats!’"
Keeping silent to keep a cellmate
At the same time, he adds, inmates who get along well with their cellmates and don’t want to lose them have an equally strong incentive to keep quiet about their symptoms, because a trip to the infirmary means that the fruit-basket-turnover logistics of prison will likely have replaced the man’s cellmate with someone new by the time he gets back. It also bears noting that the population of this particular prison — a maximum-security unit with a Death Row — fits into almost nobody’s definition of "nice." In Kaiser’s words, "These guys don’t play well with others. They’re also not the most appreciative of health care services which you try to provide."
September, October, November, and December came and went with eight, nine, six, and eight more convertors, again with significant indurations of either 10 mm to 15 mm or greater than 15 mm. At one point, prison medical staff thought they’d found "the hot case," Kaiser recalls. "One of the HIV-positive guys said he’d been coughing a good bit," he says. "We thought, this is it!" But the HIV-positive inmate turned out to be fine, with sputums (which were carefully checked for adequacy) all turning out negative.
Then came a second false alarm, an elderly inmate who’d converted in the past and had been treated for latent TB infection. The man’s wife, the medical staff discovered, had actually spent time in a TB sanitarium in the 1950s. "We thought this has got to be our guy," says Kaiser. As if to confirm everyone’s suspicions, the elderly inmate precipitously died before he could be tested. The medical examiner who did the autopsy carefully removed a slice of lung. The tissue tested negative.
Alarm bells rang again when, later in the investigation, two active cases turned up in a nearby town. Everyone who came and went at the prison, from inmate visitors to the air-conditioning repairman, was quizzed five ways from Sunday about any possible contact with the two "hot" cases — and medical staff came back empty-handed once again. "It was getting to the point where we felt like we were grasping at straws," says Kaiser. "We’d looked and looked for the smoking gun, but we couldn’t seem to find it. We were all scratching our heads in unison."
On and off throughout the episode, Tomlinson says, he’d thought about trying to contact John Bass, MD, chairman of the Department of Internal Medicine at the University of South Alabama in Mobile, and an eminence gris when it comes to the subject of skin tests.
But first, Tomlinson and Lance Luria, MD, of Correctional Medical Services, called in a well-known infectious-disease expert from Springfield, MO. The expert recollected a similar situation in a hospital in town where dozens of staff had converted. But when the hospital went back and retested, everyone came out negative. Why not go do the same thing, the ID doc advised, and see what happens?
Retesting yielded enlightening’ results
About the same time, Tomlinson and Luria did manage to track down Bass, who agreed with them. In a low-prevalence area like Missouri, Bass added, false-positives were always a possibility. To get right to the point, medical staff retested; of 50 tests, all but 12 came back negative. "We found the results very enlightening," says Kaiser.
In the wake of the experience, Tomlinson says a work group of TB experts (including state and prison representatives) is formulating an action plan for what to do if and when a similar situation occurs.
The state program’s TB control nurse, Lyinelle Phillips, RN, MPH, and Bunch will also provide a refresher course in planting and reading PPDs — not because the prison nurses’ technique appeared to be at fault, but just to be on the safe side, says Tomlinson. Also, the lots of Tubersol used for the skin tests during that long, anxious period of time will be checked to see if that’s where the problem could have occurred.
To Bass’ mind, one of four factors, in theory, must have been at work: the tests were planted incorrectly; they were read incorrectly; the reagents were stored incorrectly; or there were problems with the reagent lots. Because the first three factors seem to have been ruled out, the last is the most probable cause, Tomlinson and others suspect.
"This situation also shows that a cluster of false-positive reactions can occur with both skin-testing reagents," says Elsa Villarino, MD, MPH, chief of the therapeutics and diagnostics section of the Research and Evaluation Branch at the Division of Tuberculosis Elimination at the Centers for Disease Control and Prevention in Atlanta. "People may rely more on one product because of certain perceptions, but in reality, you can have problems with either product."
Villarino agrees with Tomlinson that irregularity in the reagent lot may have triggered the false positives. "After all, these products are biologics not made in an especially standardized way," she notes. "And you have to remember, this test is not in the category of, say, an ELISA or a Western Blot or a test for protein in urine."
Not a calibrated test
All of which is to say that the tuberculin skin test is one heck of an unreliable test. "If they tried to license it today, you can be sure the FDA would never approve it," Bass said.
These days, Kaiser confesses that he’s having a bit of a tough time accepting that after all the searching, there really is no smoking gun. There are, however, two things about which he’s sure. One is that a tough situation went as smoothly as it did because the prison medical staff and custody staff worked so well together, and because Missouri’s TB controllers and the state’s correctional system have a long and congenial relationship with one another. "I’ve talked with enough people in my position in other places to know that’s not always the case," he adds.
The second thing Kaiser knows is that 97% of the more than two million people behind bars in the U.S. eventually wind up going back home. "That means if you’re interested in public health, prisons are very much a part of the public health scene," he adds. "It also means that it’s incumbent on us to send them home as healthy as possible."
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