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The population impact of ART scale-up on the risk of new HIV infection in rural KwaZulu-Natal, South Africa Frank Tanser Presentation at IAS, Kuala Lampur 02 July 2013. Outline. Background ART coverage and risk of HIV acquisition Population viral load . Global ART scale-up.

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The population impact of ART scale-up on the risk of new HIV infection in rural KwaZulu-Natal, South AfricaFrank TanserPresentation at IAS, Kuala Lampur02 July 2013


Outline
Outline infection in rural KwaZulu-Natal, South Africa

  • Background

  • ART coverage and risk of HIV acquisition

  • Population viral load


Global art scale up
Global ART scale-up infection in rural KwaZulu-Natal, South Africa

South Africa has the worldwide largest absolute number of patients on ART,

>1.6 million by some estimates

UNAIDS Report on the Global AIDS Epidemic 2012; WHO Universal Access Report 2013; Aaron Motsoaledi 2012


Study infection in rural KwaZulu-Natal, South Africasetting

  • Adult HIV prevalence 24%

  • High levels of unemployment and poverty

  • Zulu-speaking population

  • Former homeland under apartheid


The Africa Centre infection in rural KwaZulu-Natal, South Africa

Africa Centre for Health and Population Studies


Adult life expectancy over time infection in rural KwaZulu-Natal, South Africa

13,060 deaths among 101,286

individuals aged 15 years and older, contributing

a total of 651,350 person-years of follow-up time

Bor, Herbst, Newell, and BärnighausenScience 2013


Hiv incidence by age and sex 2004 2010
HIV incidence by age and sex infection in rural KwaZulu-Natal, South Africa2004-2010

Females

Males

Tanser, Bärnighausen, Newell CROI 2011


Spatial clustering of new hiv infections
Spatial clustering infection in rural KwaZulu-Natal, South Africa of new HIV infections

Tanser et al CROI. Boston, MA; 2011.


Outline1
Outline infection in rural KwaZulu-Natal, South Africa

  • Background

  • ART coverage and risk of HIV acquisition

  • Population viral load


Population based hiv surveillance
Population-based HIV surveillance infection in rural KwaZulu-Natal, South Africa

  • Since 2003: Population-based HIV surveillance

    • Longitudinal, dynamic cohort

    • Entire adult population living in a contiguous geographical area of 438 km2 under surveillance

    • Annual rounds

    • 75% of those observed to be HIV-uninfected subsequently retest

    • All individuals geo-located

Tanser, Hosegood, Bärnighausen et al. International Journal of Epidemiology 2007


ART coverage of all HIV-infected individuals 2004-2011 infection in rural KwaZulu-Natal, South Africa

Tanser, Bärnighausen, Grapsa, Zaidi& Newell Science 2013


Population infection in rural KwaZulu-Natal, South Africaimpact of ART coverage on risk of HIV acquisition (2004-2012)

Survival analysis

> 17,000 HIV-negative individuals followed-up for HIV acquisition over 60,558 person-years

1,573 HIV sero-conversions

Time- (and space-) varying demographic, sexual behavior, economic and geographic controls, including HIV prevalence

p=0.171

P<0.0001

p<0.0001

P<0.0001

Adjusted for age, sex, community-level HIV prevalence, urban vs. rural locale, marital status, >1 partner in last 12 months, and household wealth index


Population infection in rural KwaZulu-Natal, South Africaimpact of condom use on risk of HIV acquisition (2005-2011)

Adjusted for age, sex, community-level HIV prevalence, urban vs. rural locale, marital status, >1 partner in last 12 months, and household wealth index

Tanser et al, Science, 2013


Conclusion
Conclusion infection in rural KwaZulu-Natal, South Africa

  • We find continued reductions in risk of acquiring HIV infection with increasing ART coverage in this typical rural sub-Saharan African setting

  • However, there is evidence of a “reduction saturation” effect (at coverage of >40%) under treatment guidelines of <350 CD4+ cells/µl


Outline2
Outline infection in rural KwaZulu-Natal, South Africa

  • Background

  • ART coverage and risk of HIV acquisition

  • Population viral load


Population community viral load
Population/Community viral load infection in rural KwaZulu-Natal, South Africa

  • Proposed as:

    • an aggregate measure of the potential for ongoing HIV transmission within a community

    • as a surveillance measure for monitoring uptake and effectiveness of antiretroviral therapy.


Figure 1 infection in rural KwaZulu-Natal, South Africa

CVC as a measure for assessment of HIV treatment as prevention

Miller, Powers, Smith et al Lancet Infectious Diseases 2013


Cvc as a measure for assessment of hiv treatment as prevention
CVC as infection in rural KwaZulu-Natal, South Africaa measure for assessment of HIV treatment as prevention

“ The issue of selection bias [in community viral load] could be addressed with a population-based survey in a clearly defined target population of all people in a community, including those with and without known HIV infection”

Miller, Powers, Smith et al Lancet Infectious Diseases 2013


Objectives
Objectives infection in rural KwaZulu-Natal, South Africa

  • Asses whether viral loads in this population are randomly distributed in space or whether high or low viral loads tend to cluster in certain areas

  • Assess the degree to which different population viral load summary measures highlight known areas of high incidence

  • (Establish the degree to which different population viral load summary measures predict future risk of new HIV infection in uninfected individuals)


Methods
Methods infection in rural KwaZulu-Natal, South Africa

  • All 2,456 individuals testing positive in the population-based HIV testing conducted in 2011

  • Total number DBS specimens tested was 2,420 (36 specimens excluded due to being insufficient for testing).

  • Of these, 30% (726) were below the detectable limit of 1550 copies/ml(Viljoen et al, JAIDS 2010)


Viral load distribution
Viral load distribution infection in rural KwaZulu-Natal, South Africa

Median viral load = 6428 copies per ml


Geometric mean population viral load
Geometric mean population viral load infection in rural KwaZulu-Natal, South Africa

Copies /ml


Prevalence of unsuppressed v iral load
Prevalence of unsuppressed infection in rural KwaZulu-Natal, South Africaviral load

Prevalence (%)


Adjusted hiv acquisition hazard by p revalence category
Adjusted HIV acquisition hazard by infection in rural KwaZulu-Natal, South Africaprevalence category

Adjusted for age, sex, community-level HIV prevalence, urban vs. rural locale, marital status, >1 partner in last 12 months, and household wealth index


Population prevalence of detectable virus ppdv
Population prevalence of detectable virus (PPDV) infection in rural KwaZulu-Natal, South Africa

Prevalence(%)


Conclusion1
Conclusion infection in rural KwaZulu-Natal, South Africa

  • To measure transmission potential of a community, any viral load summary index must take into account the size of the uninfected population

  • Population prevalence of detectable virus (PPDV) successfully identified known areas of continued high HIV incidence

  • We propose the PPDV as a simple community-level index of transmission potential


Acknowledgements
Acknowledgements infection in rural KwaZulu-Natal, South Africa

  • The members of the community in Hlabisa sub-district who gave their time to this research

  • Staff of the Africa Centre for Health and Population Studies and the Hlabisa HIV Care and Treatment Programme

  • Colleagues at Africa Centre (Marie-Louise Newell, Till Bärnighausen, Tulio de Oliveira,KobusHerbst, Colin Newell, Jacob Bor, JafferZaidi and many more)

  • Funding

    • Wellcome Trust (Africa Centre for Health and Population Studies)

    • National Institutes of Health grants R01 HD058482-01 and 1R01MH083539-01


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