Transcript HIV prevalence

Why does AIDS persist at such a high rate
in Sub-Saharan Africa?

Helen Epstein, in NY Times Magazine, June 13, 2004,
suggests that the reason is infidelity.
– In South Africa, Kenya and other countries, men have
several on-going commitments. This contrasts to the US
pattern of either “one night stands” or serial monogamy.

This argument is highly charged emotionally.

Can we evaluate it biologically?
00001-E-1– 27 June 2000
A global view of HIV infection
33 million adults living with HIV/AIDS as of end 1999
Adult prevalence rate
15.0% – 36.0%
5.0% – 15.0%
1.0% – 5.0%
0.5% – 1.0%
0.1% – 0.5%
0.0% – 0.1%
not available
00001-E-2– 27 June 2000
Leading causes of disease burden
globally, 1999
Rank
% of total

1
Acute lower respiratory infections
6.7

2
HIV/AIDS
6.2

3
Perinatal conditions
6.2

4
Diarrhoeal diseases
5.0

5
Ischaemic heart disease
4.1

6
Unipolar major depression
4.1

7
Cerebrovascular disease
3.5

8
Malaria
3.1

12
Tuberculosis
2.3
00001-E-3– 27 June 2000
Source: The World Health Report 2000, WHO
Leading causes of death globally, 1999
Rank
% of total

1
Ischaemic heart disease
12.7

2
Cerebrovascular disease
9.9

3
Acute lower respiratory infections
7.1

4
HIV/AIDS
4.8

5
Chronic obstructive pulmonary disease
4.8

6
Perinatal conditions
4.2

7
Diarrhoeal diseases
4.0

8
Tuberculosis
3.0

11
Malaria
1.9
00001-E-4– 27 June 2000
Source: The World Health Report 2000, WHO
Leading causes of disease burden
in Africa, 1999
Rank
% of total

1
HIV/AIDS

2
Malaria
9.9

3
Acute lower respiratory infections
8.5

4
Diarrhoeal diseases
6.5

5
Perinatal conditions
6.5

6
Measles
4.7

7
Maternal conditions
3.4

8
Tuberculosis
2.3

9
Congenital abnormalities
1.7

10
Road traffic accidents
1.7
00001-E-5– 27 June 2000
19.9
Source: The World Health Report 2000, WHO
Leading causes of death in Africa, 1999
Rank
% of total

1
HIV/AIDS
20.6

2
Acute lower respiratory infections
10.3

3
Malaria
9.1

4
Diarrhoeal diseases
7.3

5
Perinatal conditions
5.9

6
Measles
4.9

7
Tuberculosis
3.4

8
Cerebrovascular disease
3.2

9
Ischaemic heart disease
3.0

10
Maternal conditions
2.4
00001-E-6– 27 June 2000
Source: The World Health Report 2000, WHO
Changes in life expectancy in selected African countries
with high HIV prevalence, 1950 to 2000
65
60
Botswana
Uganda
South-Africa
55
Zambia
50
Zimbabwe
45
40
35
1950-55 1955-60 1960-65 1965-70 1970-75 1975-80 1980-85 1985-90 1990-95 1995-00
00001-E-7– 27 June 2000
Source: United Nations Population Division, 1998
Estimated adult HIV prevalence in Kenya,
1990-1999
16
HIV prevalence (%)
14
12
10
8
6
4
2
0
90
00001-E-8– 27 June 2000
91
92
93
94
95
96
Source: National AIDS and STD Control Programme, 1999 and UNAIDS
97
98
99
HIV prevalence among pregnant women
in South Africa, 1990 to 1999
HIV prevalence (%)
25
22.8
22.4
98
99
20
17
14.2
15
10.4
10
7.6
5
4
1.7
2.1
91
92
0.7
0
90
00001-E-9– 27 June 2000
93
94
95
Source: Department of Health, South Africa
96
97
Median HIV prevalence among pregnant women
in urban areas in Uganda, 1985 to 1998
35
HIV prevalence (%)
30
25
20
15
10
5
0
85
00001-E-10– 27 June 2000
86
87
88
89
90
91
92
93
Source: STD/AIDS Control Programme, Uganda
94
95
96
97
98
HIV prevalence in military personnel in Africa

Nigeria: 11% among peacekeepers returning
from Sierra Leone and Liberia vs 5% in adult
population

South Africa: 60-70% in military vs 20% in
adult population
00001-E-11– 27 June 2000
Source: Nigeria AIDS bulletin No 15, May 20, 2000; The Mail & Guardian, Pretoria,
March 31, 2000; UNAIDS/WHO 1999 estimate
HIV prevalence rate and frequency
of sexually transmitted infection (STI) episodes,
Carletonville miners, South Africa, 1991-1998
HIV prevalence (%)
90
80
70
60
50
40
30
20
10
0
1
2-4
5-9
Number of STI episodes
00001-E-12– 27 June 2000
Source: Ballard R, 2000 (unpublished data).
10+
Individuals are more infectious to others
when they have been newly infected

Epstein argues that the concurrent partners strategy
favors widespread transmission because a newly infected
individual is likely to visit several partners during the highly
infectious period.

An individual with “one night stands” or serial monogamy
may put fewer people at risk during this period even if the
total partners per 6 months is similar.
00001-E-13– 27 June 2000
00001-E-14– 27 June 2000
Condom use

Numerous studies have found that people in many locales
have increased use of condoms with “casual” partners or
prostitutes.

Use of condoms with regular partners has increased less
dramatically.

What if there are several “regular partners?”
00001-E-15– 27 June 2000
Why does this behavior persist?

Women without access to funds (especially younger
women) rely on male partners for financial contributions

In Kenya and South Africa, “sugar daddies” commonly
help girls with school fees as well as luxuries.
00001-E-16– 27 June 2000
Uganda’s success

Early devastating epidemic created public awareness

Cultural openness about sexual matters

Visible campaign– ABC: Abstain, Be Faithful, Use Condoms
– Zero Grazing

Participation of women’s activist groups
00001-E-17– 27 June 2000
The AIDS story as it is told in Uganda
00001-E-18– 27 June 2000
What do we know?
What do we need to know?

How can we shape this into a workable case study?

Is there adequate room for complexity, for multiple
approaches, for scientific investigation?

Can we tie in questions that lead students to explore the
mechanisms of drug action, vaccines or the immune
response?
00001-E-19– 27 June 2000
Impact of HIV/AIDS on urban households,
Côte d’Ivoire
General population
Families living with AIDS
30 000 Francs CFA
25 000
20 000
15 000
10 000
5 000
Monthly income
per capita
Monthly consumption
per capita
Savings/Disavings
0
– 5 000
00001-E-20– 27 June 2000
Source: Simulation-based on data from Bechu, Delcroix and Guillaume, 1997
Reduction in production in a household with an
AIDS death, Zimbabwe
Reduction in output
Crops

Maize
61%

Cotton
47%

Vegetables
49%

Groundnuts
37%

Cattle owned
29%
00001-E-21– 27 June 2000
Source: Stover & Bollinger, 1999
HIV prevalence rate among teenagers
in Kisumu, Kenya, by age
35
33.3
29.4
HIV prevalence (%)
30
25
22
20
17.9
boys
girls
15
10
8.6
8.3
3.6
5
0
0
0
15
00001-E-22– 27 June 2000
2.2
16
17
Age in years
18
Source: National AIDS Programme, Kenya, and Population Council, 1999
19
Age in years
Projected population structure with and
without the AIDS epidemic, Botswana, 2020
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
Projected population
structure in 2020
Males
140 120 100
80
Females
60
40
20
0
20
40
60
80
Population (thousands)
00001-E-23– 27 June 2000
Source: US Census Bureau, World Population Profile 2000
100 120 140
Deficits due to AIDS
HIV prevalence rate among
13 to 19-year-olds, Masaka, Uganda, 1989 to 1997
5
girls
HIV prevalence (%)
4
boys
3
2
1
0
1989/90
00001-E-24– 27 June 2000
1990/91
1991/92
1992/93
1993/94
Source: Kamali et al. AIDS 2000, 14: 427-434
1994/95
1995/96
1996/97
HIV prevalence rate among pregnant 15-24 year-olds
by educational status, Uganda
30
illiterate
HIV prevalence (%)
primary education
25
secondary education
20
15
10
5
0
1991-1994
00001-E-25– 27 June 2000
Source: Kilian A et al. AIDS 1999, 13: 391-398.
1995-1997
Estimated impact of AIDS on under-5 child
mortality rates, selected African countries, 2010
250
Deaths per 1000 live births
200
Without AIDS
With AIDS
150
100
50
0
Botswana
00001-E-26– 27 June 2000
Kenya
Malawi
Tanzania
Source: US Census Bureau
Zambia
Zimbabwe
Trends in HIV prevalence in selected populations
in Kampala, Uganda; Dakar, Senegal; and Thailand;
1989 to 1999
30
Kampala, <20 year old ANC
Thailand, 21 year old military conscripts
25
HIV prevalence (%)
Dakar, all ages ANC
20
15
10
5
0
89
00001-E-27– 27 June 2000
90
91
92
93
94
95
96
Source: National STD/AIDS Control Programmes, Senegal and Uganda
Armed Forces Research Institute of Medical Sciences, Thailand
97
98
99