THURSDAY, April 15 (HealthDay News) -- Low vitamin D levels are associated with progression to active tuberculosis in healthy household contacts of tuberculosis patients, according to a study published online April 14 in Emerging Infectious Diseases. Another study in the same journal found a high prevalence of latent tuberculosis infection among drug users, female sex workers, and homeless individuals in Tijuana, Mexico.
Najeeha Talat, of Aga Khan University in Karachi, Pakistan, and colleagues studied tuberculosis patients and their household contacts, 79 percent of whom were vitamin D deficient. Eight percent of disease-free household contacts progressed to active tuberculosis over a four-year follow-up. Disease progressed in 23 percent of patients in the lowest tertile for vitamin D levels, 3 percent in the middle tertile, and none in the highest tertile. Women in the lowest tertile comprised six of the eight who progressed.
Richard Garfein, Ph.D., of the University of California in San Diego, and colleagues studied 503 injection drug users, non-injection drug users, homeless individuals, and female sex workers -- all considered at high risk for HIV -- in Tijuana, Mexico. The researchers found that 57 percent of the subjects tested positive for tuberculosis, 4.2 percent tested positive for HIV, and 2.2 percent tested positive for both HIV and tuberculosis. Older age, longer duration of residence in Tijuana, and having been incarcerated in a Mexican prison were independently associated with tuberculosis infection.
"Although prevention of infection with HIV should be the top priority for reducing tuberculosis risk, the high latent tuberculosis infection prevalence found in this study indicates an unmet need for early tuberculosis identification and treatment among populations in Tijuana at risk for HIV infection," Garfein and colleagues write.
Cellestis Inc. provided QuantiFERON TB Gold assay kits at a discounted price for the second study.
Full Text - Talat
Full Text - Garfein