The effect of HIV and an Antiretroviral treatment programme on Tuberculosis transmission, incidence and prevalence in a South African Township

This doctoral work aimed to describe the epidemiology of TB in a high HIV and TB prevalent community from 1997 to 2008, and to assess the effect of HIV and a highly active antiretroviral therapy (HAART) programme on the TB epidemic in this setting

Epidemiology of HIV-1 subtypes among men who have sex with men in Cape Town, South Africa

Includes abstract.Includes bibliographical references.There are few data describing the HIV epidemic among men who have sex with men (MSM) in South Africa, and thus little information is available to inform appropriate public health response strategies for this high-risk group. One such existing knowledge gap is an understanding of HIV transmission patterns between different MSM communities and between MSM and the heterosexual population. Studies in the early 1990s identified two independent HIV-1 epidemics in Cape Town: a predominantly subtype B epidemic among white MSM and the mainly subtype C epidemic among the predominantly black heterosexual epidemic. While the heterosexual epidemic remains primarily due to subtype C virus, few recent HIV-1 subtype data are available for MSM in South Africa. This study examined circulating HIV-1 subtypes among MSM in Cape Town

Factors Associated with HIV Discussion and Condom Use with Sexual Partners in an Underserved Community in South Africa

We examined factors associated with discussing HIV and condom use with a sexual partner. Two cross-sectional surveys were conducted in 2004 prior to the implementation of an HIV awareness campaign in a South African community and in 2008 after a three-year education program. Overall, the proportion of individuals who had discussed HIV with a sexual partner increased from 76% in 2004 to 89% in 2008 (p < .001). Among respondents who had sex six months before completing the surveys, condom use significantly increased from 64% in 2004 to 79% in 2008 (p < .05). Respondents who discussed HIV with a sexual partner were more likely to use condoms than respondents who had not discussed HIV with a sexual partner (OR=2.08, 95% CI=1.16, 3.72). These findings indicate the importance of interventions aimed at promoting HIV awareness and discussion of HIV in communities with individuals at risk of acquiring HIV

Childhood tuberculosis infection and disease: A spatial and temporal transmission analysis in a South African township

Background. Tuberculosis (TB) remains a leading cause of South African mortality and morbidity. While adult TB arises from both recent and prior infection, childhood TB results from recent infection and reflects ongoing transmission occurring despite current TB control strategies. Setting. A South African community with high rates of TB and HIV disease. Outcomes. A Geographic Information System was used to spatially and temporally define the relationships between TB exposure, infection and disease in children <15 years of age, with exposure to adult HIV-positive and HIV-negative TB disease on residential plots between 1997 and 2007. Results. During the study period the annual adult TB notification rate increased from 629 to 2106/100,000 and <15yrs TB notification rate ranged between 664/100,000 and 1044/100,000. The mean exposure to adult TB for uninfected children, TB-infected, TB cases was 5.1%, 5.4% and 33% per annum and the mean number of adult smear-positive cases per exposed child was 1.0, 1.6 and 1.9 respectively. Acquisition of TB infection was not associated with HIV status of adult exposure TB case and 36% of child TB cases were diagnosed prior to the temporally closest adult case on their plot. Conclusions. Childhood infection and disease were quantitatively linked to infectious adult TB prevalence in an immediate social network. Childhood infection should be monitored in high burden settings as a marker of ongoing TB transmission. Improved knowledge of township childhood and adult social networks may also facilitate targeted active case finding, which may provide an adjunct to presently failing TB control strategies

Decreasing household contribution to TB transmission with age: a retrospective geographic analysis of young people in a South African township

BACKGROUND: Tuberculosis (TB) transmission rates are exceptionally high in endemic TB settings. Adolescence represents a period of increasing TB infection and disease but little is known as to where adolescents acquire TB infection. We explored the relationship between residential exposure to adult TB cases and infection in children and adolescents in a South African community with high burdens of TB and HIV. METHODS: TB infection data were obtained from community, school-based tuberculin skin test (TST) surveys performed in 2006, 2007 and 2009. A subset of 2007 participants received a repeat TST in 2009, among which incident TB infections were identified. Using residential address, all adult TB cases notified by the community clinic between 1996 and 2009 were cross-referenced with childhood and adolescent TST results. Demographic and clinic data including HIV status were abstracted for TB cases. Multivariate logistic regression models examined the association of adult TB exposure with childhood and adolescent prevalent and incident TB infection. RESULTS: Of 1,100 children and adolescents included in the prevalent TB infection analysis, 480 (44%) were TST positive and 651 (59%) were exposed to an adult TB case on their residential plot. Prevalent TB infection in children aged 5-9 and 10-14 years was positively associated with residential exposure to an adult TB case (odds ratio [OR]:2.0; 95% confidence interval [CI]: 1.1-3.6 and OR:1.5; 95% CI: 1.0-2.3 respectively), but no association was found in adolescents [greater than or equal to]15years (OR:1.4; 95% CI: 0.9-2.0). HIV status of adult TB cases was not associated with TB infection (p=0.62). Of 67 previously TST negative children, 16 (24%) converted to a positive TST in 2009. These incident infections were not associated with residential exposure to an adult TB case (OR: 1.9; 95% CI: 0.5-7.3). CONCLUSIONS: TB infection among young children was strongly associated with residential exposure to an adult TB case, but prevalent and incident TB infection in adolescents was not associated with residential exposure. The HIV-status of adult TB cases was not a risk factor for transmission. The high rates of TB infection and disease among adolescents underscore the importance of identifying where infection occurs in this age group

TB transmission is associated with prolonged stay in a low socio-economic, high burdened TB and HIV community in Cape Town, South Africa

Abstract Background While several studies have assessed the associations between biological factors and tuberculosis (TB) transmission, our understanding of the associations between TB transmission and social and economic factors remains incomplete. We aimed to explore associations between community TB transmission and socio-economic factors within a high TB-HIV burdened setting. Methods We conducted a cross-sectional molecular epidemiology study among adult patients attending a routine TB clinic. Demographic and clinical data were extracted from TB registers and clinical folders; social and economic data were collected using interviewer-administered questionnaires; Mycobacterium tuberculosis isolates were genotyped and classified as clustered/non-clustered using IS6110-based Restriction Fragment Length Polymorphism. Composite “social” and “economic” scores were generated from social and economic data. Data were analyzed using StataCorp version 15.0 software. Stratified, bivariable analyses were performed using chi-squared. Wilcoxon signed rank tests; univariable and multivariable logistic regression models were developed to explore associations in the social, economic, traditional and composite TB risk factors with TB transmission. Results Of the 505 patient Mtb  strains, 348(69%) cases were classified as clustered and 157(31%) were non-clustered. Clustered cases were more likely to have lived longer in the study community, (odds ratio [OR] = 1.05, 95% Confidence interval [C.I]:1.02–1.09, p = 0.006); in the same house (OR = 1.04, C.I: 0.99–1.08, p = 0.06); and had increased household crowding conditions (i.e fewer rooms used for sleeping, OR = 0.45, C.I:0.21–0.95, p = 0.04). Although a higher proportion of clustered cases had a low economic score, no statistically significant association was found between clustering and either the economic score (p = 0.13) or social score (p = 0.26). Conclusions We report a novel association between Mtb transmission and prolonged stay within a high burdened community. Transmission was also associated with fewer rooms for sleeping in a household. Increased social interaction and prolonged residence in a high burdened community are important factors linked to Mtb transmission, possibly due to increased probability of higher effective contact rates. The possible importance of degrees of poverty within low socio-economic setting warrants further study

Burden of New and Recurrent Tuberculosis in a Major South African City Stratified by Age and HIV-Status

CITATION: Wood, R. et al. 2011. Burden of new and recurrent tuberculosis in a major South African city stratified by age and HIV-status. PLos ONE, 6(10): e25098, doi:10.1371/journal.pone.0025098.The original publication is available at http://journals.plos.org/plosoneAim To describe the burden of tuberculosis (TB) in Cape Town by calculating TB incidence rates stratified by age and HIV-status, assessing the contribution of retreatment disease and estimating the cumulative lifetime TB risk in HIV-negative individuals. Methods Details of TB cases were abstracted from the 2009 electronic TB register. Population denominators were estimated from census data and actuarial estimates of HIV prevalence, allowing calculation of age-specific and HIV-stratified TB notification rates. Results The 2009 mid-year population was 3,443,010 (3,241,508 HIV-negative and 201,502 HIV-positive individuals). There were 29,478 newly notified TB cases of which 56% were laboratory confirmed. HIV status was recorded for 87% of cases and of those with known HIV-status 49% were HIV-negative and 51% were positive. Discrete peaks in the incidence of non-HIV-associated TB occurred at three ages: 511/100,000 at 0–4 years of age, 553/100,000 at 20–24 years and 628/100,000 at 45–49 years with 1.5%, 19% and 45% being due to retreatment TB, respectively. Only 15.5% of recurrent cases had a history of TB treatment failure or default. The cumulative lifetime risks in the HIV-negative population of all new TB episodes and new smear-positive TB episodes were 24% and 12%, respectively; the lifetime risk of retreatment disease was 9%. The HIV-positive notification rate was 6,567/100,000 (HIV-associated TB rate ratio = 17). Although retreatment cases comprised 30% of the HIV-associated TB burden, 88% of these patients had no history of prior treatment failure or default. Conclusions The annual burden of TB in this city is huge. TB in the HIV-negative population contributed almost half of the overall disease burden and cumulative lifetime risks were similar to those reported in the pre-chemotherapy era. Retreatment TB contributed significantly to both HIV-associated and non-HIV-associated TB but infrequently followed prior inadequate treatment. This likely reflects ongoing TB transmission to both HIV-negative and positive individuals.http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0025098Publisher's versio

Estimating age-mixing patterns relevant for the transmission of airborne infections.

INTRODUCTION: Age-mixing patterns can have substantial effects on infectious disease dynamics and intervention effects. Data on close contacts (people spoken to and/or touched) are often used to estimate age-mixing. These are not the only relevant contacts for airborne infections such as tuberculosis, where transmission can occur between anybody 'sharing air' indoors. Directly collecting data on age-mixing patterns between casual contacts (shared indoor space, but not 'close') is difficult however. We demonstrate a method for indirectly estimating age-mixing patterns between casual indoor contacts from social contact data. METHODS: We estimated age-mixing patterns between close, casual, and all contacts using data from a social contact survey in South Africa. The age distribution of casual contacts in different types of location was estimated from the reported time spent in the location type by respondents in each age group. RESULTS: Patterns of age-mixing calculated from contact numbers were similar between close and all contacts, however patterns of age-mixing calculated from contact time were more age-assortative in all contacts than in close contacts. There was also more variation by age group in total numbers of casual and all contacts, than in total numbers of close contacts. Estimates were robust to sensitivity analyses. CONCLUSIONS: Patterns of age-mixing can be estimated for all contacts using data that can be easily collected as part of social contact surveys or time-use surveys, and may differ from patterns between close contacts

High prevalence of self-reported undiagnosed HIV despite high coverage of HIV testing : a cross-sectional population based sero-survey in South Africa

CITATION: Kranzer, K. et al. 2011. High prevalence of self-reported undiagnosed HIV despite high coverage of HIV testing : a cross-sectional population based sero-survey in South Africa. PLoS ONE, 6(9): e25244, doi:10.1371/journal.pone.0025244.The original publication is available at http://journals.plos.org/plosoneObjectives To measure HIV prevalence and uptake of HIV counseling and testing (HCT) in a peri-urban South African community. To assess predictors for previous HIV testing and the association between the yield of previously undiagnosed HIV and time of last negative HIV test Methods A random sample of 10% of the adult population (≥15 years) were invited to attend a mobile HCT service. Study procedures included a questionnaire, HIV testing and CD4 counts. Predictors for previous testing were determined using a binominal model. Results 1,144 (88.0%) of 1,300 randomly selected individuals participated in the study. 71.0% (68.3–73.6) had previously had an HIV test and 37.5% (34.6–40.5) had tested in the past 12 months. Men, migrants and older (>35 years) and younger (<20 years) individuals were less likely to have had a previous HIV test. Overall HIV prevalence was 22.7 (20.3–25.3) with peak prevalence of 41.8% (35.8–47.8) in women aged 25.1–35 years and 37.5% (26.7–48.3) in men aged 25.1–45 years. Prevalence of previously undiagnosed HIV was 10.3% (8.5–12.1) overall and 4.5% (2.3–6.6), 8.0% (CI 3.9–12.0) and 20.0% (13.2–26.8) in individuals who had their most recent HIV test within 1, 1–2 and more than 2 years prior to the survey. Conclusion The high burden of undiagnosed HIV in individuals who had recently tested underscores the importance of frequent repeat testing at least annually. The high prevalence of previously undiagnosed HIV in individuals reporting a negative test in the 12 months preceding the survey indicates a very high incidence. Innovative prevention strategies are needed.http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0025244Publisher's versio