Indoor Social Networks in a South African Township: Potential Contribution of Location to Tuberculosis Transmission

CITATION: Wood, R. et al. 2012. Indoor social networks in a South African township : potential contribution of location to tuberculosis transmission. PLoS ONE, 7(6): e39246, doi:10.1371/journal.pone.0039246.The original publication is available at http://journals.plos.org/plosoneBackground We hypothesized that in South Africa, with a generalized tuberculosis (TB) epidemic, TB infection is predominantly acquired indoors and transmission potential is determined by the number and duration of social contacts made in locations that are conducive to TB transmission. We therefore quantified time spent and contacts met in indoor locations and public transport by residents of a South African township with a very high TB burden. Methods A diary-based community social mixing survey was performed in 2010. Randomly selected participants (n = 571) prospectively recorded numbers of contacts and time spent in specified locations over 24-hour periods. To better characterize age-related social networks, participants were stratified into ten 5-year age strata and locations were classified into 11 types. Results Five location types (own-household, other-households, transport, crèche/school, and work) contributed 97.2% of total indoor time and 80.4% of total indoor contacts. Median time spent indoors was 19.1 hours/day (IQR:14.3–22.7), which was consistent across age strata. Median daily contacts increased from 16 (IQR:9–40) in 0–4 year-olds to 40 (IQR:18–60) in 15–19 year-olds and declined to 18 (IQR:10–41) in ≥45 year-olds. Mean daily own-household contacts was 8.8 (95%CI:8.2–9.4), which decreased with increasing age. Mean crèche/school contacts increased from 6.2/day (95%CI:2.7–9.7) in 0–4 year-olds to 28.1/day (95%CI:8.1–48.1) in 15–19 year-olds. Mean transport contacts increased from 4.9/day (95%CI:1.6–8.2) in 0–4 year-olds to 25.5/day (95%CI:12.1–38.9) in 25–29 year-olds. Conclusions A limited number of location types contributed the majority of indoor social contacts in this community. Increasing numbers of social contacts occurred throughout childhood, adolescence, and young adulthood, predominantly in school and public transport. This rapid increase in non-home socialization parallels the increasing TB infection rates during childhood and young adulthood reported in this community. Further studies of the environmental conditions in schools and public transport, as potentially important locations for ongoing TB infection, are indicated.http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0039246Publisher's versio

Working conditions and tuberculosis mortality in England and Wales, 1890-1912:a retrospective analysis of routinely collected data

BACKGROUND: Modelling studies suggest that workplaces may be important sites of Mycobacterium tuberculosis transmission in high burden countries today. Contemporary data on tuberculosis by occupation from these settings are scarce. However, historical data on tuberculosis risk in different occupations are available and may provide insight into workplace transmission. We aimed to ascertain whether, in a high burden setting, individuals working in crowded indoor environments (exposed) had greater tuberculosis mortality than individuals employed elsewhere (unexposed). METHODS: The Registrar General's Decennial Supplements from 1890-2, 1900-2 and 1910-2 contain data on mortality from tuberculosis by occupation for men in England and Wales. In these data, the association between occupational exposure to crowded indoor environments and tuberculosis mortality was assessed using an overdispersed Poisson regression model adjusting for socioeconomic position, age and decade. RESULTS: There were 23,962 deaths from tuberculosis during 14.8 million person-years of follow-up among men working in exposed occupations and 28,483 during 19.9 million person-years of follow-up among men working in unexposed occupations. We were unable to categorise a large number of occupations as exposed or unexposed. The adjusted rate ratio for death from tuberculosis was 1.34 (95 % confidence interval 1.26-1.43) comparing men working in exposed occupations to those in unexposed occupations. CONCLUSIONS: Tuberculosis mortality in England and Wales at the turn of the 20th century was associated with occupational exposure to crowded indoor environments. The association between working conditions and TB in contemporary high burden settings requires further study

Public Transportation and Tuberculosis Transmission in a High Incidence Setting

BACKGROUND:Tuberculosis (TB) transmission may occur with exposure to an infectious contact often in the setting of household environments, but extra-domiciliary transmission also may happen. We evaluated if using buses and/or minibuses as public transportation was associated with acquiring TB in a high incidence urban district in Lima, Peru. METHODS:Newly diagnosed TB cases with no history of previous treatment and community controls were recruited from August to December 2008 for a case-control study. Crude and adjusted odd ratios (OR) and 95% confidence intervals (CI) were calculated using logistic regression to study the association between bus/minibus use and TB risk. RESULTS:One hundred forty TB cases and 80 controls were included. The overall use of buses/minibuses was 44.9%; 53.3% (72/135) among cases and 30.4% (24/79) among controls [OR: 3.50, (95% CI: 1.60-7.64)]. In the TB group, 25.7% (36/140) of subjects reported having had a recent household TB contact, and 13% (18/139) reported having had a workplace TB contact; corresponding figures for controls were 3.8% (3/80) and 4.1% (3/73), respectively[OR: 8.88 (95% CI: 2.64-29.92), and OR: 3.89 (95% CI: 1.10-13.70)]. In multivariate analyses, age, household income, household contact and using buses/minibuses to commute to work were independently associated with TB [OR for bus/minibus use: 11.8 (95% CI: 1.45-96.07)]. CONCLUSIONS:Bus/minibus use to commute to work is associated with TB risk in this high-incidence, urban population in Lima, Peru. Measures should be implemented to prevent TB transmission through this exposure

Transportation and a Pandemic: A Case Study of COVID-19 Pandemic

People use various modes for travelling and interact with each other during their trips for business, shopping, education and tourism. The travel increases the risk of spreading communicable diseases and may escalate the spreading rate at a level that can make an endemic to become a pandemic. On the other hand, the measures, for example, lockdown, taken by governments to control the pandemic, negatively impact travels and, in the worst case, bring the transportation system to a standstill. Thus, it is important to understand this relationship between a pandemic and transportation to control the spread of a disease through transportation and to suppress the negative impacts of that disease on transportation. This book chapter explores this relationship using the COVID-19 pandemic as a case study. Firstly, the chapter highlights the role of transportation in spreading any disease, including COVID-19. Secondly, it summarizes the immediate impacts of COVID-19 on transportation and puts forward ways to recover transport systems after a pandemic. Thirdly, the chapter provides insights into how policymakers can use the scenarios like lockdown to reshape transport systems. Finally, this chapter suggests some proactive approaches that transport agencies can adopt during and after a pandemic