Why is HIV Prevalence So Severe in Southern Africa?, and “What Works” (and Doesn’t) for AIDS Prevention? Daniel Halperin, PhD, MS Senior Advisor for Behavior Change/Primary Prevention, USAID With assistance from colleagues at USAID, World Bank, Global Fund, UCSF, etc.

Key Points * Back to the Basics: using a “basic public health” approach to prevention Using evidence (vs. politics, ideology, etc.) to set priorities *Prevention works (Uganda today compared to yrs. ago) [Please see the “notes” under most of the slides!]

HIV PREVALENCE BY REGION Source: Adapted from WHO AFRO 2003 Report Southern Africa Eastern Africa Central Africa West Africa % HIV prevalence 2004 Report on the Global AIDS Epidemic (Fig 8)

TRANSMISSION DYNAMICS  Epidemic concentrated - if transmission occurs largely among vulnerable groups and vulnerable group interventions would reduce overall infection  Epidemic generalized - if transmission occurs primarily outside vulnerable groups and would continue despite effective vulnerable group interventions  Epidemics DON’T inevitably keep escalating

HIV TRANSMISSION PATTERNS IN ACCRA, GHANA, 2003 Sources: GAC/NAP and Cote et al data, 2004

HIV TRANSMISSION PATTERNS IN MASHONALAND CENTRAL, ZIMBABWE Sources: Wilson and Cowan et al data, 2003

Economic Status and HIV prevalence (Tanzania) Source: AIS

Education Status and HIV prevalence in Tanzania Source: AISS

Why is HIV so much Higher in Southern Africa?? Multiple concurrent partnerships (“nyatsi,” “lishende,” “small house,” “second office”...) Lack of male circumcision And various other factors, such as relatively developed/highly mobile societies, income inequality, gender dynamics, "dry sex,” etc.

Source: 2002 Lesotho BSS

“Concurrent” Partnerships * Source M. Carael, 1995; Halperin and Epstein, 2004

“Concurrent” Partnerships * Source M. Carael, 1995; Halperin and Epstein, 2004

Proportion of year-olds reporting more than one current sexual partner, South Africa 2005 Source: South African National HIV Prevalence, HIV Incidence, Behavior and Communication Survey, 2005

“ Map” of the largest component of a sexual network in Likoma, Malawi Source: Kohler H and Helleringer S. The Structure of Sexual Networks and the Spread of HIV in Sub-Saharan Africa: Evidence from Likoma Island (Malawi). PARC Working Paper Series: WPS 06-02

A NATION AT WAR WITH HIV&AIDS Low degree networks create a transmission core In largest component: 2% 41% 64% 10% Mean: 1.74 Mean: 1.80 Mean: 1.86 Largest components Mean: 1.68 Number of Partners Bicomponents in red Source: Martina Morris, Univ. of Washington, used with permission from a presentation given at a meeting on concurrent sexual partnerships and sexually transmitted infections at Princeton University, 6 May 2006.

Transmission efficiency “Mathematical models estimate the average probability of male–female transmission of HIV-1 per unprotected coital act to be between and 0.003% during chronic HIV infection, which in itself would not sustain an epidemic.” -Pao et al, AIDS (2005)

“Acute Infection” and Concurrence

Source: WHO/GPA surveys BEHAVIOURAL AND HIV TRENDS IN UGANDA

CONCLUSION MCP is a driver Behavior can be changed Challenge – HOW Social Movement