Characteristics of tuberculosis source cases uncovered

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Characteristics of TB source cases uncovered
Characteristics of TB source cases uncovered

HealthDay News — In 26 United States tuberculosis outbreaks, the initial source case-patients had long incubation periods and were characterized by substance abuse, incarceration, and homelessness, according to a study published in the U.S. Centers for Disease Control and Prevention's Emerging Infectious Disease.

“As the frequency of tuberculosis (TB) cases continues to decline in the United States, however, so does provider experience with its diagnosis, which raises the possibility that the recent trend toward more cases of pulmonary TB being diagnosed in later disease stages might be a related consequence,” noted Maryam B. Haddad, MPH, of the CDC in Atlanta, and colleagues

After identifying characteristic of TB cases that started outbreaks in the U.S. during 2002 to 2001, the investigators found that in 20 of the outbreaks, the source case-patient was also the first patient in the outbreak to come to the attention of public health authorities.

Case-patients had long infectious periods (median, 10 months), reported the study authors. These patients often experienced delays in diagnosis and treatment initiation after seeking medical attention for TB symptoms. Pulmonary tuberculosis smear-positive for acid-fast bacilli was confirmed in all case patients.

Most patients reported excess alcohol or illicit drug use; half had been incarcerated, and nearly half had been homeless in the year prior to diagnosis. Most of the cases came to public attention because the patient sought care for symptoms.

"This review underscores the particular importance of prompt and thorough investigations for tuberculosis cases confirmed by positive smear for acid-fast bacilli in which patients have experienced substance abuse, incarceration, or homelessness," wrote the researchers.


  1. Haddad MB et al. Emerging Infectious Diseases. 2015; doi: 10.3201/eid2103.141475
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