Background People living in urban informal settlements are a vulnerable population. The total number of South African households living in an informal settlement or a shack (not in a backyard) was 1 779 426 in 2011. Overcrowding and...
moreBackground
People living in urban informal settlements are a vulnerable population. The total number of South African households living in an informal settlement or a shack (not in a backyard) was 1 779 426 in 2011. Overcrowding and inadequate housing contributes to the spread of pulmonary tuberculosis. The objective of this review was to investigate the epidemiology of and the programmatic response to TB in people living in urban informal settlements in South Africa.
Methodology
This review included studies in which participants were recruited from urban informal settlements and townships. Qualitative studies, case studies, case series studies and modelling studies were excluded from the review. A comprehensive search strategy was used to search a number of electronic databases. Two people independently screened the results of the searches and applied the eligibility criteria. Four people independently extracted data from the list of included studies using a standard data extraction form. Research findings have been described narratively, including the characteristics of included studies and their risk of bias.
Results
66 studies were included in the review out of an initial total of 505: 23 studies investigated TB risk, incidence and prevalence, 5 studies investigated TB transmission dynamics, 19 studies investigated TB diagnostics and 20 studies investigated TB prevention, treatment and health systems. Seventy-seven studies were excluded after retrieval of full text article.
Ten studies reported on the prevalence of TB infection and eight studies reported on the prevalence of TB disease. ARTI or incidence rate of infection was reported in four studies and the incidence of TB disease was reported in five studies.
The five studies reporting on TB transmission dynamics were observational studies conducted in the Western Cape Province in poor communities with high TB and HIV prevalence. The studies were conducted between 1993 and 2007.
The twenty studies investigating TB prevention, treatment and health systems mainly focused on: the effect of co-administration of antiretroviral and TB treatment (one study), integration of TB and HIV care in primary healthcare (seven studies), community contribution to tuberculosis control (four studies), health care utilization of severely immune suppressed HIV infected persons accessing a national treatment program (one study) and TB preventive chemotherapy or TB treatment therapy (seven studies).
Of the diagnostic studies, the earliest studies were done in 2003 and the latest studies were done in 2010.Seventeen studies were from informal settlements in the Western Cape (Khayelitsha, Gugulethu and Ravensmead/Uitsig) and two from
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Gauteng (Soweto). Different diagnostic methods were investigated, including tuberculin skin tests, interferon gamma release assays, Gene Xpert and urine lipoarabinomannan.
Discussion
The majority of the studies reporting on TB incidence and prevalence were conducted in urban informal settlements in the Western Cape. The extent to which these findings can be generalized to other informal settlements across the country is unclear. Most of these studies were of low or moderate quality, which limits the validity of the findings.
Crowding, the number of shebeens and unemployment rate were associated with increased TB case load in the studies looking at transmission. However, the risk of bias was often unclear in a number of the studies.
A few studies included reported low rates of loss to follow-up among TB patients, however this outcome needs to be measured in future studies to have a better estimate. Integration of HIV/TB services increased the number of HIV/TB co-infected patients who were initiated on antiretroviral treatment and reduced the time between start of TB treatment and initiation of antiretroviral treatment. However, evidence from the studies that evaluated the contribution of the community was conflicting.
In the diagnostic studies, a high prevalence of latent TB infection (LTBI) was found in paediatric contacts of adults TB cases. For the diagnosis of TB in adults, Xpert MTB/RIF improved the diagnosis of smear negative cases, especially in comparison to sputum microscopy. For the diagnosis of TB in children, a symptom-based approach worked well in HIV negative children. No randomised trials were included in this section, hence the studies may have been confounded and some, by design, were biased.
Conclusion
This review highlights the gap in research on the incidence and prevalence of TB disease and infection in people living in informal settlements and risk factors for disease acquisition. If we have an improved understanding of the transmission dynamics of tuberculosis in urban informal settlements we could perhaps design and implement strategies to contain the spread of the disease.
