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Development Problems in Africa
Spring 2006
Week 3: HIV/AIDS in Africa
Takashi Yamano
FASID
Contents
Economics of Communicable Diseases
– Market Failures
HIV/AIDS in Africa
– Infections and Prevalence
– Preventions
– Treatments
– Vaccines
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Economics of Communicable Diseases
Background on Communicable Diseases
 Every year, 1.1 million people, mostly children and
pregnant women, die of malaria (90% of them are in
Africa)

Every year, 1.9 million people die of tuberculosis
(98% in developing countries, many in Africa).

In 2003, 2.9 million people died of AIDS (total of over
20 million since 1981). About 38 million people are
living with HIV.
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Kremer (2000a) “Creating Markets for New Vaccines Part I”
Deaths from Diseases for which Vaccines are Needed
Diseases
Deaths (millions)
%
AIDS
2.3
27.5
Tuberculosis
Malaria
Pneumococcus
Rotavirus
1.5
1.1
1.1
0.8
18.0
13.3
13.2
9.6
Shigella
E.Coli
Others
0.6
0.5
-
7.2
6.0
-
8.3
100
Total
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Kremer (2000b) “Creating Markets for New Vaccines Part II”
Failures in the Market of Vaccines
Under Consumption of Vaccines



Individuals who take vaccines not only benefit
themselves, but also break the chain of disease
transmission. They do not, however, such external
benefits into account.
The chief beneficiaries of vaccines are often children.
Individuals seem much more willing to pay for
treatment than prevention.
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Kremer (2000b) “Creating Markets for New Vaccines Part I”
Monopoly Market
Monopoly Profit
Alternatively: The government pay
A + B + C + D to the firm, taxing Group
X just below MP and Group Y just over
MC. >> everyone is better off !
Monopoly
Price (MP)
A
E
Willingness to pay
D
Manufactu
ring Cost
(MC)
B
C
0
Group A
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Group B
1
Fraction of population
vaccinated
Kremer (2000b) “Creating Markets for New Vaccines Part I”
Social vs. Private Returns

Private returns to curing the disease is based on the
income saved by taking drugs or vaccines.

But because infectious diseases spread among
people, the social returns have to take into account
the saved incomes of potential patients who would be
infected by the disease from the particular patient.

Thus, Social Returns of a communicable disease is
higher than the private returns. Negative Externality!

Implication: medical costs of communicable diseases
should be subsidized. Earlier the interventions are,
the lower the costs.
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Kremer (2000b) “Creating Markets for New Vaccines Part I”
Understanding HIV and AIDS
1981 Reported in The Morbidity and
Mortality Weekly Report, CDC
1983 The HIV is identified by Luc Montagnier,
followed by Robert Gallo
(for details see And the Band Played On by
Randy Shilts or video)
2006 25 years after the first report about AIDS
HIV: Human Immunodeficiency Virus
AIDS: Acquired Immunodeficiency Syndrome
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How the virus Works: Infection
• HIV attacks a particular set of sells in the human immune
system known as CD4 cells. CD4 cells
• organize the body’s overall immune response, and
• engulf foreign invaders and ensure that the body’s immune system
will recognize them.
• HIV enters CD4 cells and makes copies of themselves,
destroying the CD4 cells.
• At infection, the immune system responses and the vital
load is high, “the window period.” A person is highly
infectious and can not be detected for HIV because of high
levels of CD4 cells.
>> The more people there are in the early stage of
infection, the greater the chance of effective transmission
between people.
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Barnett and Whiteside (2002) AIDS in the 21st century
Probability of HIV-1 infection per exposure
Female-to-Male, unprotected sex
Infection per
1000 exposure
0.33 – 1.0
Male-to-female, unprotected sex
1–2
Male-to-male, unprotected anal sex
5 – 30
Needle stick
3
Mother-to-child transmission
Exposure to contaminated blood products
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130 – 480
900 – 1,000
World Bank (1997) Confronting AIDS
Epidemiology 101
• An Epidemic is a rate of disease that reaches unexpectedly
high levels, affecting a large number of people in a relatively
short time.
• A disease is considered as Endemic if it is continuously
present in a population (e.g., malaria).
• A pandemic describes epidemics of world wide proportions
(e.g., influenza in 1918 or HIV/AIDS).
• Incidence is the number of new infections which occur over
a time period.
• Prevalence is the absolute number of infected people in a
population.
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Barnett and Whiteside (2002) AIDS in the 21st century
Prevalence: A Global Overview
Region
Number of adults
(15-49) living with
HIV (millions)
23
0.9
6.3
HIV prevalence
rate among
adults (15-49)
7.5
0.1
0.6
E. Europe & C. Asia
Western Europe
N. Africa & Middle East
1.3
0.57
0.46
0.6
0.3
0.2
North America
Caribbean
Latin America
0.99
0.41
1.6
0.6
2.3
0.6
36
1.1
Sub-Saharan Africa
East Asia
South & SE Asia
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Total
Source: UNAIDS (2004) Report on the global AIDS Epidemic
HIV Prevalence: Urban vs. Rural
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Source: UNAIDS (2004) Report on the global AIDS Epidemic
Changes in HIV: Men vs. Women
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Source: UNAIDS (2004) Report on the global AIDS Epidemic
HIV Prevalence in Kenya
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Why in Africa?
– Largely unknown
– Known or the conventional hypothesis
• It originated from Central Africa
• More than 90% of adult HIV infection is due to
(hetero-) sexual transmission
• Economic development and globalization helped:
the virus spreads because people spreads
Examples: Drivers, Migration workers, prostitutes
• Poor health care systems exaggerated the epidemic
• Sexually Transmitted Infections increase infections
per exposure
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Source: UNAIDS (2004) Report on the global AIDS Epidemic
Life expectancy in selected countries
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Source: UNAIDS (2004) Report on the global AIDS Epidemic
Demographic Outlook in South Africa
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Source: UNAIDS (2004) Report on the global AIDS Epidemic
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Source: UNAIDS (2004) Report on the global AIDS Epidemic
Prevention
Target Groups
• In low-prevalence settings: target key
population groups (e.g., sex workers and clients,
injecting drug users, men who have sex with
men)
• In high-prevalence settings: key groups and the
total population
Prevention efforts should be accompanied with
universal access to treatment, impact and
vulnerability-reduction measures.
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Prevention
Projects
• AIDS education and awareness
• Behavior change programs
• Condom promotion
• Voluntary counsel and testing
• Preventing and treating STIs
• Prevent mother-to-child transmission
• Harm reduction programs for drug users
• Safe blood supply
• Infection control in health care settings
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Prevention
ABCs in HIV preventions
• A means Abstinence: not engaging in sexual
intercourse or delaying sexual initiation.
• B means Being Faithful: being faithful to one’s
partner or reducing the number of sexual
partners.
• C means Condom use: condoms reduce the
risk of HIV transmission.
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Source: UNAIDS (2004) Report on the global AIDS Epidemic
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Source: UNAIDS (2004) Report on the global AIDS Epidemic
The Success Story: Uganda
The national HIV prevalence rate declined from 15% in 199a
to 5% in 2001
Why?
– High-level political support
– Behavior Change Communication (BCC) interventions
reached the general population and key target groups
– Early and significant mobilization of Ugandan religious
leaders
– A decrease in multiple sexual partnerships
– Use of condoms
Source: Hogle, et al., USAID, 2002
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Treatment
• Five to six million people in low-and middle-income
countries need antiretroviral treatment immediately. But
only 0.4 million (7%) in 2003 receive it (WHO).
• The price has come down from over $10,000 to $300 per
person per year.
• The 3 by 5 Initiative: Treating 3 million people by 2005
(WHO)
– This initiative did not achieve the target (3 million) but
helped the triple the number of people with access to
drugs from 0.4 to 1.3 million people in just two years.
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Source: UNAIDS (2004) Report on the global AIDS Epidemic
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Source: UNAIDS (2004) Report on the global AIDS Epidemic