Week 3: HIV/AIDS in Africa Takashi Yamano Development Problems in Africa Spring 2006

Contents Economics of Communicable Diseases –Market Failures HIV/AIDS in Africa –Infections and Prevalence –Preventions –Treatments –Vaccines

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. Kremer (2000a) “Creating Markets for New Vaccines Part I”

Deaths from Diseases for which Vaccines are Needed DiseasesDeaths (millions)% AIDS Tuberculosis Malaria Pneumococcus Rotavirus Shigella E.Coli Others-- Total 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. Kremer (2000b) “Creating Markets for New Vaccines Part I”

Monopoly Market A B E C D Monopoly Price (MP) Manufactu ring Cost (MC) 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 ! Willingness to pay Fraction of population vaccinated Group A 0 1 Group B 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. Kremer (2000b) “Creating Markets for New Vaccines Part I”

Understanding HIV and AIDS 1981Reported in The Morbidity and Mortality Weekly Report, CDC 1983The HIV is identified by Luc Montagnier, followed by Robert Gallo (for details see And the Band Played On by Randy Shilts or video) years after the first report about AIDS HIV: Human Immunodeficiency Virus AIDS: Acquired Immunodeficiency Syndrome

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.

Barnett and Whiteside (2002) AIDS in the 21 st century

Probability of HIV-1 infection per exposure Infection per 1000 exposure Female-to-Male, unprotected sex0.33 – 1.0 Male-to-female, unprotected sex1 – 2 Male-to-male, unprotected anal sex5 – 30 Needle stick3 Mother-to-child transmission130 – 480 Exposure to contaminated blood products900 – 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.

Barnett and Whiteside (2002) AIDS in the 21st century

Prevalence: A Global Overview RegionNumber of adults (15-49) living with HIV (millions) HIV prevalence rate among adults (15-49) Sub-Saharan Africa237.5 East Asia South & SE Asia E. Europe & C. Asia Western Europe N. Africa & Middle East North America Caribbean Latin America Total361.1 Source: UNAIDS (2004) Report on the global AIDS Epidemic

HIV Prevalence: Urban vs. Rural

Source: UNAIDS (2004) Report on the global AIDS Epidemic Changes in HIV: Men vs. Women

HIV Prevalence in Kenya

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

Source: UNAIDS (2004) Report on the global AIDS Epidemic

Life expectancy in selected countries

Source: UNAIDS (2004) Report on the global AIDS Epidemic Demographic Outlook in South Africa

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.

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

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.

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

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.

Source: UNAIDS (2004) Report on the global AIDS Epidemic