Household-based HIV and TB intervention boosts HIV testing, lowers community TB prevalence

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At the 19th Conference on Retroviruses and Opportunistic Infections in Seattle, Dr. Helen Ayles presented some key results on behalf of the ZAMSTAR team from the first randomized trial of a combined HIV and TB intervention strategy to demonstrate a reduction in population prevalence of tuberculosis.

The study, conducted in 24 communities in Zambia and South Africa, tested two interventions to reduce community-wide TB prevalence—community-based enhanced TB case finding and a household intervention using the TB patient in the household as a gateway. The community intensified case finding intervention had no effect on TB prevalence in the community.

Twelve of the 24 communities received the household intervention, which utilized lay counselors and community workers to counsel household members on TB and HIV risks and facilitated HIV and TB testing of household members.  The study found a reduction of 22 percent in the household intervention arm of the study.  There was also a substantial uptake in HIV testing among household members, with 76 percent of those testing reporting no previous test compared to controls.  Uptake of antiretroviral therapy (ART) increased in both arms with no measurable difference in the intervention arm.  According to Ayles, most of the newly identified HIV-infected individuals in the intervention arm were not currently eligible for ART under country guidelines.  A reduction of TB incidence was also found by measuring transmission in community school children.  There was no impact on HIV incidence.

The study group speculates that the household intervention’s impact on the community must arise from wider effects than just those in the household, given that only six percent of the total population was directly involved in the household intervention.  Mathematical modeling is now under way to model the effects of scale up and the mechanism of action of the intervention.  This intervention could be an important component of TB/HIV intervention scale up moving forward.  The intervention is also cheap, less than $1 per person.

Ayles noted that these results are really important and that they plan to integrate this model into the PopART—HIV Prevention Trials Network (HPTN) 071 trial of combination prevention, which will include universal testing and immediate ART for those identified as HIV-infected.  This trial is one of three being funded through the U.S. President’s Emergency Plan for AIDS Relief (PEPFAR) program to test combination prevention strategies, including ART, for community-wide impact on HIV incidence.

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