HIV incidence time trend and characteristics of recent seroconverters in a rural community with high HIV prevalence: South Africa

Transcription

1 HIV incidence time trend and characteristics of recent seroconverters in a rural community with high HIV prevalence: South Africa Till Bärnighausen 1, Oscar Bangre 2, Frank Tanser 1, Graham Cooke 3, Marie-Louise Newell 1,4 1 Africa Centre for Health and Population Studies, University of KwaZulu-Natal, South Africa 2 Navrongo Health Research Centre, Ghana 3 Imperial College, UK 4 University College, London, UK Presentation at CROI 2009, Montreal 11 February 2009

2 Outline Background HIV incidence trend Characteristics of recent seroconverters Summary

3 Objectives To test whether HIV incidence has decreased, increased or remained constant in the past five years in a rural community in Hlabisa sub-district, South Africa To describe the characteristics of the people who have HIV seroconverted in the period in the community to inform HIV prevention approaches, targeting, and placement

4 Location Africa Centre for Health and Population Studies DSA = demographic surveillance area

5 Africa Centre for Health and Population Studies Established in 1997 with a core grant from the Wellcome Trust, UK Since 2000: Africa Centre Demographic Information System (ACDIS) and geographic information system (GIS) Since 2001: Socioeconomic household survey Since 2003: Population-based HIV surveillance Longitudinal open cohort Annual rounds All adult residents of the Africa Centre DSA eligible for HIV testing Source: Tanser, Hosegood, Bärnighausen et al. International Journal of Epidemiology 2007

6 Outline Background HIV incidence trend Characteristics of recent seroconverters Summary

7 Methods Eligibility criteria for analysis: Individuals had to have tested in the Africa Centre HIV surveillance at least twice during the observation period (July 2003 to December 2007) have tested HIV-seronegative when they first participated in the surveillance be resident in the Africa Centre DSA at the time of the first HIV test meet the age eligibility criteria during the initial negative HIV test and the later test(s): women and men years of age Random assignment of seroconversion dates in the interval between last negative and first positive HIV test 8,095 individuals; id 16,256 person-years at risk; 563 seroconversions Source: Bärnighausen, Tanser & Newell (2009) AIDS Research and Human Retroviruses (forthcoming)

8 HIV incidence over time 8 7 HIV incide ence (per 100 perso on-years) Pooled HIV incidence: 3.4 per 100 person years (95% CI ) 2003/II 2004/I 2004/II 2005/I 2005/II 2006/I 2006/II 2007/I 2007/II Period Source: Bärnighausen, Tanser & Newell (2009) AIDS Research and Human Retroviruses (forthcoming)

9 Outline Background HIV incidence trend Characteristics of recent seroconverters Summary

10 Methods Eligibility criteria for analysis: Individuals had to have tested in the Africa Centre HIV surveillance at least twice during the observation period (July 2003 to December 2008) have tested HIV-seronegative when they first participated in the surveillance be resident in the Africa Centre DSA at the time of the first HIV test meet the age eligibility criteria during the initial negative HIV test and the later test(s): women and men years of age 770 seroconverters Midpoint imputation of seroconversion dates Observation closest in time to (seroconversion date half a year) selected from other Africa Centre datasets (demographic surveillance, socioeconomic survey, geographic information system)

11 At what age does seroconversion occur? 100 Women Men % % of total recent seroconverters are women Age at seroconversion

12 Are recent seroconverters in school or employed?

13 Where do seroconverters live? 11% of seroconverters became migrants between enrolment and seroconversion Note: The blue dots do not represent true household locations. Random errors have been added to the true locations.

14 Did people access VCT before seroconversion? VCT? No Yes Public clinic Public hospital Private clinic Private hospital Work Other VCT = voluntary counseling and testing

15 How close is public infrastructure from recent seroconverters households? PS SS FC MC % PS = primary school SS = secondary school FC = fixed public clinic MC = mobile mobile clinic Distance from household to nearest structure (km)

16 What is the HIV status of adult members of seroconverters homesteads? % homesteads with # % homesteads with # ever HIV+ members newly HIV+ individuals ( ) ( ) 3 members 1 member 2 members 0 members 1 member 0 members

17 What do seroconverters know about ART? Have you heard of ART? No No No Yes Yes Yes Do you know where to obtain ART? Do you personally know somebody who takes ART? ART = antiretroviral treatment

18 Outline Background HIV incidence trend Characteristics of recent seroconverters Summary

19 Summary HIV incidence id has remained constant t at a high h level l since 2003 in this rural community despite ongoing HIV prevention interventions More than 60% of all seroconversions occur in people below the age of 25 and more than 80% occur before the age of 30 Almost 50% of seroconversions below 25 years of age occur in people who are neither in school nor employed Homesteads of recent seroconverters are widely dispersed across urban and rural areas At least one other HIV positive adult in more than 50% of recent seroconverters homesteads One other adult who seroconverted in the period in 12% of recent seroconverters homesteads Almost two thirds of recent seroconverters has heard of ART One third of the recent seroconverters who have heard of ART personally know somebody who takes ART Half of recent seroconverters accessed VCT before seroconversion

20 Implications New approaches or intensified ifi effort to prevent HIV infection with established methods required School-based interventions promising, but should include component for out-of-school youth Prevention interventions need to reach rural and urban populations as well as migrants VCT coverage and effectiveness need to improve New approaches to HIV prevention promising Family-based prevention Integration of ART and HIV prevention

21 Acknowledgements We thank Phumzile Dlamini, Thobeka Mngomezulu, Zanomsa Gqwede, Nhlanhla Mbizana, Claudia Wallrauch, Kobus Herbst and the field staff at the Africa Centre for Health and Population Studies at the University of KwaZulu-Natal, South Africa, for their work in collecting the data used in this study and the communities in the Africa Centre demographic surveillance area for their support and participation in this study. Core funding for the Africa Centre's Demographic Surveillance Information System (GR065377/Z/01/H) and Population-based HIV Survey (GR065377/Z/01/B) was received from the Welcome Trust, UK. Till Bärnighausen and Frank Tanser were supported by grant 1R01- HD from the National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), USA.