of the infection risk to prison workers, but an instructor was among those who developed active tuberculosis.

Jones and colleagues studied the transmission of tuberculosis in a city jail in Memphis, Tennessee, where inmates were housed for a median of 1 day, often returning several times to the same facility, commonly housed in rooms holding up to 36 inmates (58). During a 3-year period beginning in January 1995, 38 inmates were recognized as tuberculous, and five guards developed tuberculosis. RFLP fingerprinting demonstrated that one strain of M. tuberculosis was responsible for the disease in 16 of 24 inmates for whom results were available and two of the five guards. Tuberculin testing of guards revealed a conversion rate of 2.7 percent in an unknown time period and of 1.2 percent during a subsequent 1-year interval.

Two studies of tuberculosis in prisons are of particular interest because they give some insights into the risk of tuberculous infection in relation to that in the community. In a study of 28 contact investigations in New York City correctional facilities, Johnsen noted that the tuberculin conversion rate among inmates exposed to sputum smear-positive prisoners with tuberculosis was 6.6 percent (59). On the other hand, when the investigation revealed that a putative index case did not, in fact, have tuberculosis, the conversion rate was 5.5 percent, not significantly different from the rate among those exposed to documented cases of tuberculosis. Johnsen suggested that some of the conversions were confounded by booster effects.

Erdil and Stahl reported preemployment tuberculin reactor rates for the Connecticut Department of Corrections for 1991 and 1992 (60). Because they reported age cohort-specific data, it is possible to calculate the actual annual risk of infection that these individuals brought with them to the workplace from the communities in which they resided. In this respect, this report is nearly unique and of considerable importance. For the 25- to 40-year-old age range, the calculated annual risk of infection was 0.18 percent/year. This rate is relatively high when compared to that for the adult U.S. population as a whole, but it is similar to the 0.20 percent/ year estimated ARI for black males.

Risk in Homeless Shelters

That tuberculosis is a problem among the urban homeless is well known, having been widely publicized in the lay press. In New York City, 68 percent of tuberculosis patients discharged from Harlem Hospital in 1988 were homeless (61), and 30 percent of all tuberculosis cases in 1991 were homeless (62). The shelters where these individuals spend their nights are often in substandard buildings with limited ventilation, and the sleeping conditions are generally crowded, thus facilitating the spread of airborne infections among the clients. Using both drug sensitivity pat-



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