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.

Why is HIV Prevalence SoSevere 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 10-15 yrs. ago)

[Please see the “notes” under most of the slides!]

HIV PREVALENCE BY REGION

Source: Adapted from WHO AFRO 2003 Report

0

5

10

15

20

25

30

35

1990199119921993199419951996199719981999200020012002

Southern Africa

Eastern Africa

Central AfricaWest Africa

% H

IV p

revale

nce

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 PATTERNSIN ACCRA, GHANA, 2003

0%

10%

20%

30%

40%

50%

60%

70%

80%

ANC prevalence Sex worker

prevalence

Adult male

infections from

sex workSources: GAC/NAP and Cote et al data, 2004

HIV TRANSMISSION PATTERNS IN MASHONALAND CENTRAL, ZIMBABWE

0%

10%

20%

30%

40%

50%

60%

Pregnant women

HIV prevalence

Sex worker

prevalence

Male infections

from sex workSources: Wilson and Cowan et al data, 2003

Economic Status and HIV prevalence (Tanzania)

0

2

4

6

8

10

12

lowest second middle fourth highest

womenmen

Source: 2003-2004 AIS

Education Status and HIV prevalence in Tanzania

012345678910

noeducation

primaryincomplete

primarycomplete

secondary+

womenmen

Source: 2003-2004 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

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 15-24 year-olds reporting more than one current sexual partner, South Africa

2005

05

101520253035404550

Males Females Total

15-19

20-24

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

Sour

ce: K

ohle

r H a

nd H

elle

ringe

r S. T

he S

truc

ture

of S

exua

l Net

wor

ks a

nd th

e Sp

read

of

HIV

in S

ub-S

ahar

an A

fric

a: E

vide

nce

from

Lik

oma

Isla

nd (M

alaw

i). P

ARC

Wor

king

Pap

er

Serie

s: W

PS 0

6-02

A NATION AT WAR WITH HIV&AIDS

Low degree networks create a transmission core

In largest component: 2% 41%

64%10%

Mean:

1.74Mean:

1.80Mean:

1.86

Largestcomponents

Mean:

1.68Number ofPartners

Bicomponentsin 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 0.0005 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

0

10

20

30

40

1989

1995

1989 35 16 15

1995 15 6 3

Men with one or more "casual" partners in

past year

Women with one of more "casual" partners

in past year

Men with three or more "non-regular" partners

in the past year0

5

10

15

20

1991 15

2003 4.1

Adult HIV prevalence

CONCLUSION

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