Abstract
BackgroundIn high incidence settings, the majority of Mycobacterium tuberculosis (M.tb) transmission occurs outside the household. Little is known about where people’s indoor contacts occur outside the household, and how this differs between different settings. We estimate the number of contact hours that occur between adults and adult/youths and children in different building types in urban areas in Western Cape, South Africa, and Zambia.MethodsData were collected from 3206 adults using a cross-sectional survey, on buildings visited in a 24-h period, including building function, visit duration, and number of adults/youths and children (5–12 years) present. The mean numbers of contact hours per day by building function were calculated.ResultsAdults in Western Cape were more likely to visit workplaces, and less likely to visit shops and churches than adults in Zambia. Adults in Western Cape spent longer per visit in other homes and workplaces than adults in Zambia. More adults/youths were present at visits to shops and churches in Western Cape than in Zambia, and fewer at homes and hairdressers. More children were present at visits to shops in Western Cape than in Zambia, and fewer at schools and hairdressers. Overall numbers of adult/youth indoor contact hours were the same at both sites (35.4 and 37.6 h in Western Cape and Zambia respectively, p = 0.4). Child contact hours were higher in Zambia (16.0 vs 13.7 h, p = 0.03). Adult/youth and child contact hours were highest in workplaces in Western Cape and churches in Zambia. Compared to Zambia, adult contact hours in Western Cape were higher in workplaces (15.2 vs 8.0 h, p = 0.004), and lower in churches (3.7 vs 8.6 h, p = 0.002). Child contact hours were higher in other peoples’ homes (2.8 vs 1.6 h, p = 0.03) and workplaces (4.9 vs 2.1 h, p = 0.003), and lower in churches (2.5 vs 6.2, p = 0.004) and schools (0.4 vs 1.5, p = 0.01).ConclusionsPatterns of indoor contact between adults and adults/youths and children differ between different sites in high M.tb incidence areas. Targeting public buildings with interventions to reduce M.tb transmission (e.g. increasing ventilation or UV irradiation) should be informed by local data.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-016-1406-5) contains supplementary material, which is available to authorized users.
Highlights
In high incidence settings, the majority of Mycobacterium tuberculosis (M.tb) transmission occurs outside the household
Supplementing ‘case finding’ based control measures with ‘place finding’ based methods is a promising approach for reducing incidence [3], but is currently hampered by a poor understanding of where Mycobacterium tuberculosis (M.tb) transmission occurs in high incidence settings
Results are presented from 3206 adults: 1270 (40 %) from Western Cape, South Africa, and 1941 (60 %) from Zambia (Table 1). 1661 (52 %) respondents were female, and 1550 (48 %) were male
Summary
The majority of Mycobacterium tuberculosis (M.tb) transmission occurs outside the household. Supplementing ‘case finding’ based control measures with ‘place finding’ based methods is a promising approach for reducing incidence [3], but is currently hampered by a poor understanding of where Mycobacterium tuberculosis (M.tb) transmission occurs in high incidence settings. Individual outbreaks of M.tb infection have been linked to a wide range of settings, including public transport [8, 9], schools [10], churches [11, 12] and healthcare facilities [13, 14] These kinds of study provide some information on locations where transmission can occur, but as outbreak investigations are typically only undertaken when unusual patterns of disease are noticed, they give little insight into the types of location where transmission is most common
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