Most reports on nursing homes have examined the transmission of M. tuberculosis in nursing home residents. Data from the mid-1980s suggest that the incidence of active tuberculosis may be almost twice as high among elderly nursing home residents as among elderly people living in the community (CDC, 1990b). In 1998, residents (all ages) of nursing homes and long-term-care facilities accounted for 3.5 percent of tuberculosis cases nationwide (CDC, 1999b).
In the early 1980s, two reports of tuberculosis outbreaks in nursing homes pointed to workplace transmission of tuberculosis infection and disease to workers (Stead, 1981; Munger et al., 1983). Another report on a skin testing program for workers on a chronic care ward in a Veterans Administration Medical Center found evidence of “occult” transmission of endemic tuberculosis (Brennen et al., 1988).
Since 1995, New York State has required acute-care hospitals and long-term-care facilities to report clusters of tuberculin skin test conversion and evidence of nosocomial tuberculosis transmission as well as cases of active tuberculosis (Rachel L.Stricof, Bureau of Tuberculosis Control, New York State Department of Health, personal communication, October 3, 2000). The number of reports and the seriousness of the events reported have declined over that period. Between 1995 and 1997, covered facilities reported 15 clusters of possible or confirmed tuberculin skin test conversion among health care workers. One of the 15 clusters involved a hospitalized patient who was considered no longer infectious and was transferred to a long-term-care facility that subsequently failed to maintain appropriate therapy for the person. The other clusters were associated with exposure to unsuspected or unconfirmed index cases. During this same period, eight pseudo-outbreaks were reported involving clusters of skin test conversions linked, for example, to atypical mycobacteria or deficiencies in the tuberculin skin test procedure. Since 1998, the state has undertaken numerous contact investigations but has not documented any further outbreaks involving patients or health care workers in recent years.
Recently, investigators at the Arkansas Department of Health reported on probable transmission of tuberculosis to two health care workers from a resident of a nursing home who died in a hospital with undiagnosed tuberculosis. Investigators later located a radiograph for the individual showing a cavitary lesion (Ijaz et al., 1999). The investigation started when the nursing home’s surveillance program detected skin test conversions in four previously negative employees. The secondary cases of active tuberculosis included an employee in the nursing home where the source patient was a resident, a nurse in the hospital that treated the source patient, and a nursing home resident who moved from the nursing home that housed the source patient to a second jointly operated facility in the community. DNA fingerprinting found the same strain of M. tuberculosis in all three individuals. On-site investigation determined that the source resident was very