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Although the surge in tuberculosis that was seen in the U.S. during the 1990s has subsided, experts fear that worldwide patterns mean TB will not be eradicated any time soon in this country. Results from two new studies have implications for domestic control strategies.
Patients with pulmonary tuberculosis often are assumed to be minimally infectious if sputum smears show no tubercle bacilli. Researchers in the Netherlands used contact tracing and DNA fingerprint analysis to establish transmission patterns among more than 1200 patients with pulmonary tuberculosis and found that smear-negative patients did indeed transmit disease. Overall, they were 25% as infectious as were those with positive smears; an estimated 13% of the entire study coh…