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U.S. Department of Health and Human Services


TB Notes Newsletter

No. 2, 2005


Trial to Compare 6 Months vs Continuous IPT
Launched in Botswana

Botswana has one of the highest rates of TB in the world (reported incidence of 623 cases per 100,000 population in 2002) and a very high prevalence of HIV infection (37.4% prevalence among pregnant women attending antenatal clinic, 2003 data). Since people living with HIV/AIDS (PLWHA) are at much higher risk of developing active pulmonary TB than individuals with normal immune systems, the World Health Organization recommended in 1998 that PLWHA receive short-term isoniazid preventive therapy (IPT) to treat latent TB infection.

IPT substantially reduces the risk that a person with latent TB infection (LTBI) will progress to TB disease. However, once the course of prophylactic treatment ends, PLWHA can be reinfected with TB, especially in countries such as Botswana where TB is highly endemic. A major clinical trial expected to enroll 1,800 HIV-infected adults was launched on November 23, 2004, in order to compare the standard 6 months of IPT with continuous IPT. The catchment area for the trial includes Botswanaís two major urban areas, Francistown and Gaborone. This 4-year study will be the first such long-term assessment of the efficacy of continuous IPT among HIV-infected persons. The primary objective of the trial is to determine if continuous IPT (36 months) is superior to limited IPT (6 months) to prevent active TB, hospitalization, and death in PLWHA. Secondary objectives include estimating subject compliance with limited vs. continuous IPT, ascertaining the causes of morbidity and mortality among subjects, quantifying the generation of INH resistance in subjects who develop active TB during or after IPT, and identifying risk factors for the development of TB in persons taking limited vs. continuous IPT. Additionally, restriction fragment length polymorphism (RFLP) analysis will be performed on mycobacterial isolates in order to identify clusters which could suggest recent transmission, as well as to estimate the relative burden of recent transmission compared with progression to TB disease from LTBI.

The trial is designed to be closely allied with the existing government IPT program so that outcomes will be readily useful to a public health program. In lieu of a pilot of the study, the study was started gradually, but shortly the pace of enrolment will accelerate. As of January 10, 2005, 30 persons were enrolled in the Botswana IPT Trial.

Submited by Taraz Samandari, MD
Div of TB Elimination


Released October 2008
Centers for Disease Control and Prevention
National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention
Division of Tuberculosis Elimination -

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