Epidemiology of tuberculosis in HIV-infected persons in Santiago, Chile

Abstract

Chile is a country early in the HIV epidemic with a low but increasing prevalence of HIV infection predominantly transmitted through sexual exposure (91.6%). The majority of HIV transmission has been in homosexual males, however the incidence in women is steadily increasing. TB infection, however, has maintained a low and stable prevalence due to a rigorous control program. As the HIV epidemic in Chile progresses, coinfection with TB and HIV can pose a further public health threat by increasing the incidence of drug-resistant TB, increasing the window of transmissibility for TB infection, and increasing the morbidity and mortality of patients with AIDS. In this three part study, we reviewed records and interviewed patients among a 430 patient cohort in the HIV-control program treated between January 1988 and June 1998 at the Hospital Sotero del Rio in the South-Eastern Metropolitan Region of Santiago, Chile. Risk factors were studied through an administered questionnaire and the effect of TB on HIV progression was examined through a detailed examination of a 30 patient cohort. Among the HIV cohort, prevalences of 7.14%, 6.9%, 5.1%, and 6.6% of TB cases confirmed either clinically or bacteriologically were found for years 1994 through 1997, respectively. Prevalences of bacteriological confirmation were 5.1%, 5.4%, 3.9%, and 3.7%, respectively. These levels are consistent with measures made prior to 1994 by the Ministry of Health and fail to demonstrate significant increase. 72.2% co-infected patients displayed pulmonary TB alone, while 22.2% displayed extrapulmonary TB, and 5.5% displayed both pulmonary and extrapulmonary infection. These results do not corroborate high levels of extrapulmonary TB found in many other cohorts of coinfected patients. 13.9% patients demonstrated relapse of TB, which is consistent with other reports. 21.1% co-infected patients died while still infectious for TB, 5.3% abandoned treatment, and 105% remain of unknown disposition. Rates of abandonment and death while infectious were significantly higher than rates in patients with TB alone suggesting higher vigilance in TB control of coinfected patients may be important to prevent spread of TB from this highly susceptible population.