A Cluster randomized trial of two intensified TB case finding
strategies in an urban community severely affected by HIV.
Project Principal Investigator : DR ELIZABETH CORBETT
Tuberculosis control has markedly deteriorated in Southern Africa because of
the HIV epidemic. Case-notification rates in Zimbabwe have increased ten-fold
during the last two decades, with urban sites having the highest rates.
Although there is increasing consensus that novel approaches are needed, the ideal
strategy for controlling TB in countries severely affected by HIV has not been
established. Intensified case finding is one possible approach that has a high
potential impact, but little potential for doing harm.
In response to this, DETECTB, a research study
is conducting a 4.5 year study (March 2005 to 2009) cluster randomized trial of
two intensified TB case-finding strategies in a high density community severely
affected by HIV with the aim of comparing the cumulative yield and residual
burden of the two methods and to investigate HIV-specific point prevalence and
incidence of active TB disease in the community before and after the
The study is being conducted in the western part of Harare with the aim of:
Providing an extra services to pick up infectious TB more quickly, aiming to
reduce the spread of infection (“enhanced TB case-finding”). Improving control
of TB in the selected neighbourhood and if successful, reduce the risk of
becoming infected with TB Models of TB infection and disease in high HIV
prevalence communities will be developed. The aim will be to allow fuller
interpretation of study data and also to explore the likely impact and
limitations of intensified case finding and other potential TB control
strategies, and the impact of HIV on key aspects of TB epidemiology likely to
affect the relative efficacy of different control strategies.
The results may lead to better control of TB in the future, especially in
cities where HIV is common The study is funded by Wellcome Trust, UK, and is
being conducted in collaboration with: Biomedical Research and Training
Institute (BRTI) Harare City Health London School of Hygiene and Tropical
Medicine, UK In consultation with the Ministry of Health and Child Welfare
World Health Organization International Union Against TB and Lung Disease What
the DETECTB study is doing Study Sites Census data was used to subdivide ten
neighbourhoods in the study area into forty-six clusters with approximately
2,000 adults per cluster, each of which was surrounded by a buffer zone of
approximately 500metres to minimise contamination.
The clusters are in Harare High Density Western Suburbs namely, Rugare,
Kambuzuma, Warren Park, Mufakose, Kuwadzana Highfield, GlenNorah, GlenView,
Budiriro and Dzivarasekwa. Each of the households in the clusters was chosen
for a 4-stage study.
STAGE 1 – HOUSEHOLD SURVEY: 2005 Door to door household visits were made
to explain about the study and to find out the number of people in the study
areas. Baseline demographic and social data was also collected for each of the
STAGE 2 – PREVALENCE SURVEY: 2005-2006 One in ten households that
expressed willingness to participate, or were not sure, or were not seen in
Stage 1 were offered a thorough check-up for TB and confidential HIV test for
all adults (16 years and above) in the family in a mobile clinic. Participants
diagnosed with active TB disease were referred for treatment. Participants
taking TB treatment at the time of survey were considered to have active TB
disease only if still culture-positive at the time of their inclusion in the
STAGE 3 – INTERVENTION SURVEY: 2006-2009 Screening interviews are being
conducted to detect individuals with symptoms suggestive of TB (cough for 3 weeks
or greater, unintentional weight loss, drenching night sweats), and to collect
sputum specimens for smear microscopy from symptomatic individuals identified
through 6-monthly door-to-door interviews, or mobile TB clinic visits to each
cluster. In each case community sensitisation is being carried out before and
during each 6-monthly intervention using posters, leafleting, and meetings with
community representatives and community-based organizations involved in HIV and
TB care and control. The aim will be to deliver the respective intervention 6
times during a three-year period Identified symptomatic individuals will have
two sputum specimens collected for microscopy and culture. Individuals found to
be smear positive or smear negative but persistently symptomatic will be
referred to the project clinic for follow-up and further management.
HIV PREVALENCE IN TB PATIENTS SURVEY: 2006 Confidential HIV Screening
and interviews are being conducted to determine HIV prevalence among TB
Patients registering at Beatrice Infectious Disease Hospital (BRIDH) and
Wilkins Hospital for the first time.
STAGE 4 – PREVALENCE SURVEY: 2009 A repeat of STAGE 2 will be conducted.
This will provide an estimate of the residual burden of infectious disease left
by each strategy, as well as determining whether point prevalence has been
reduced in the whole study area during the intervention period.