TB rates decline in 1997 for fifth year
TB rates decline in 1997 for fifth year
Successes dampened by outbreaks
Another year of declining tuberculosis rates in the United States is expected for 1997, but widespread outbreaks, some of them fairly large and unexpected, underscore concerns that clinicians may be too complacent in detecting the pathogen.
"It looks like we will have another decline this year, at least as much as last year or maybe more," says Kenneth Castro, MD, director of the division of TB elimination at the Centers for Disease Control and Prevention (CDC). "We still have a few states that haven't finalized their figures, and that is why we are not making them available yet, but from preliminary data, it looks promising."
New cases in 1996 declined nearly 7% across the country, marking the fourth consecutive year that nationwide TB rates had declined. A total of 21,327 cases were reported in 1996, compared with 22,860 cases reported in 1995. Rates were down 13% in New York, 11% in Texas, and 8% in California.
A random survey of state health officials also confirms that rates were down last year.
"I think they will be down nationwide but not in all states and, indeed, like last year, the rates will be up in some states where we least expect them," says Lee Reichman, MD, director of the National Tuberculosis Center in Newark, NJ.
In Florida, there were 1,400 TB cases last year, down 17 cases from 1996. At Jackson Memorial Hospital in Miami, however, there were five more cases last year (148), after a 35-case decline the previous year, says Joan Otten, RN, director of TB control there.
"I think because of the large number of foreign-born and homeless and HIV-positive patients here, we are probably going to remain steady," she says.
The CDC recently reported statistics from Westchester County, NY, showing a 60% increase in tuberculosis cases between 1996 and 1997, due mainly to a large case drop in 1996. In St. Louis County, which does not include the city of St. Louis, the 47 new cases reported last year is a 46% increase from 1997.
Plethora of outbreaks
The good news of TB case reductions last year, which was to be announced for World TB Day on March 24, doesn't mean clinicians can become complacent, however, as is evident in numerous outbreaks, some yet to be reported. Health officials in New Jersey, for example, will report on World TB Day of a recent rash of outbreaks in high schools and colleges in their state, Reichman says.
"We now have nine outbreak situations in high schools and colleges in New Jersey," he tells TB Monitor. "Seven of those nine situations are not inner city cases, and all patients could have been given isoniazid but weren't."
The outbreaks signified "that we are doing a good job of controlling TB in the inner city, but when it gets out of the inner city, we are doing a poor job because a lot of practicing physicians are taking care of [TB] patients," Reichman says.
The CDC recently reported on an outbreak from 1994 to 1996 of a virulent strain of tuberculosis in rural communities in two counties in Tennessee and Kentucky. First reported in TB Monitor in its November 1996 issue, the outbreak infected 21 patients with TB, while 72% of 429 contacts had positive skin test - including 86 with documented skin-test conversions. The TB strain also had a ten-times greater reproductive rate in infected mice. Researchers note in a recent issue of the New England Journal of Medicine that infection with the TB strain was not associated with an increase of active TB; however, they suggest this may be due to the quick response by surveillance teams and the early introduction of isoniazid treatment.1 As a team of epidemiologists investigate the outbreak, other exposures are expected, health officials note.
Outbreaks have not been limited to rural areas, however. In St. Louis, where new active TB cases increased 36% last year from 1996, health officials recently reported that two dozen patients and staff at a residential care facility were infected by a man who was infected with a rare form of drug-resistant TB.
Reference
1. Valway S, Sanchez M, Shinnick T, et al. An outbreak involving extensive transmission of a virulent strain of mycobacterium tuberculosis. New Engl Journ Med 338; 633-638.
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