A cluster-randomized trial of two intensified TB case-finding strategies in an urban community severely affected by HIV

CORBETT, ELIZABETH and MUNGOFA, STANLEY A cluster-randomized trial of two intensified TB case-finding strategies in an urban community severely affected by HIV. UNSPECIFIED. (In Press)

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Abstract

Undiagnosed TB can remain infectious for prolonged periods and is the main source of ongoing TB transmission in the community. On average, one person with TB will infect only about 10 others per year spent with untreated smear-positive disease, but with prolonged infectiousness before diagnosis (mean of 2 years globally) keeping the number of secondary infections high enough to maintain the transmission cycle. In Africa, adult HIV prevalence was the strongest predictor of National TB case-notification rates by the beginning of this decade but relatively little of the burden of undiagnosed infectious TB in the community is attributable to HIV, because of a much briefer mean period of smear-positivity. The implications are that, on average, each HIV-negative TB patient contributes far more to TB transmission than each HIV-positive TB patients (having a longer infectious period in which to transmit) and that the brief infectiousness of HIV-related TB is likely to mitigate the impact of the HIV-related TB epidemic on overall community TB transmission rates. This is in keeping with TB transmission data from Africa showing no major impact from the HIV epidemic. Current international policy concerning TB control in HIV prevalent settings does not promote community-based case-finding, but instead is based on DOTS (prompt investigation and effective treatment of smear-positive TB in patients reporting chronic cough to health facilities), with promotion of additional interventions for individuals known to be HIV-positive, including active case-finding and joint HIV/TB care. Although interventions targeted to known HIV-infected persons are necessary for HIV care, their contribution towards control of TB transmission may be limited because: - HIV-related TB usually presents before HIV has been diagnosed, limiting the population-level impact of interventions at or after the time of HIV-testing, and Including HIV-negative individuals is necessary as they are likely to be responsible for most TB transmission events, even in high HIV prevalence populations, due to their prolonged infectiousness Periodic community-based case-finding was widely used in industrialized countries and parts of Asia during the last century, but was not widely evaluated for impact on prevalent TB. The aims of this study were: To compare the cumulative yield and residual burden of two potentially sustainable intensified TB case-finding methods applied once every 6 months for 6 rounds in a high HIV prevalence setting Household enquiry for chronic coughers, and Promotion of self-reporting of chronic cough to a mobile diagnostic unit. To investigate point prevalence and incidence of active TB disease before and after the intervention period, stratified by HIV status To develop dynamic mathematical models in order to explore further the impact of HIV and the likely efficacy of strategies for improving TB control in high HIV prevalence areas

Item Type: Other
Subjects: R Medicine > RZ Other systems of medicine
Divisions: Research Units > Research Centre
Depositing User: Mr. Luxmore Chiwuta
Date Deposited: 22 Nov 2011 08:02
Last Modified: 29 Nov 2011 14:03
URI: http://researchdatabase.ac.zw/id/eprint/49

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