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Infectious Disease in Africa: lessons learned and their application

Infectious Disease in Africa: lessons learned and their application

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Infectious Disease in Africa: lessons learned and their application

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  1. Infectious Disease in Africa:lessons learned and their application Michael Welsh, Ph.D.

  2. Topics • Population structure and public health challenges • Infectious disease • HIV Epidemiology • Lessons learned in HIV prevention

  3. Population of Sub-Saharan Africa by Age and Sex: 2000 to 2005 Male Female Age group < 15 represents 44% of the total population Source: U.S. Bureau of Census.

  4. Fertility Decline in Selected World Regions, Early 1960s to 2005 Children per woman* * The average total number of children a woman will have given current birth rates. Source: US Bureau of the Census, International Data Base, September 23, 2002.

  5. Use and Total Unmet Need* Women 15-49 *All women 15-49, modern methods. **Currently married women 15-49, modern methods. Source: Demographic and Health Surveys.

  6. Infant Mortality by Birth Interval On average, infants born after short birth intervals are twice as likely to die as those born after intervals of two or more years. * Figures here are only for a 2 year birth interval instead of a 2-3 year interval. Source: Country DHS Reports.

  7. Agent Host Environment Disease Traditional Epidemiological Framework Source: Center for Health and the Global Environment, Harvard Medical School

  8. Leadingcauses of death in Africa, 2000 22.6 25.0 20.0 15.0 % of Total 10.1 9.1 10.0 6.7 5.5 4.3 3.6 3.1 2.9 2.3 5.0 0.0 HIV/AIDS Malaria Perinatal conditions Tuber culosis Cerebro vascular disease Measles Lower respiratory infections Diarrhoeal disease Ischaemic Heart disease Maternal conditions Source: The World Health Report 2001, WHO

  9. Infectious disease deaths as proportion of all deaths by region, 2001

  10. Question • Why do you think that Africa has such a serious problem with ID?

  11. Poverty: root cause - poor most vulnerable Demographics: children and women vulnerable Poor nutrition/food supply: weakens immunity Access to water ? Urbanization/housing Environmental factors Public health systems Risk behaviors Factors that contribute to infectious disease in Africa

  12. Per capita gross national income by region(US $) Source: Sachs J. et al., Ending Africa’s Poverty Trap, Brookings Institution, 2004

  13. Health Expenditures per Capita

  14. Physicians per 100,000 people: 1990-2002 Source: Human Development Report 2003 New York: Oxford University Press, 2003

  15. Measles coverage at 1 year World Development Indicators, World Bank, 2002

  16. Nutritional Deficits • Annual population increase 2.5 % • Population doubles in approximately 20 years • FAO estimate that 50 % already go “hungry” • Per capita food production has declined since the 70s • Little to no food surplus

  17. Access to Improved Water Sources Source: USAID (2002)

  18. AIDS Mortality Cumulative mortality in US thru Dec 2001 Mortality in sub-Saharan Africa in a single year, 2002

  19. HETEROGENEITY OF HIV IN AFRICA 0-0.1% 1-5% 3-7% 15-35%

  20. 50 45 40 35 30 25 20 15 10 5 0 86 88 90 92 94 96 98 00 02 04 HETEROGENEITY OF HIV IN AFRICAA TALE OF THREE EPIDEMICS Manzini, Swaziland Kampala, Uganda Dakar, Senegal

  21. PREVENTION LESSONS FROM GENERALIZED EPIDEMICS • Stigma • Concurrent sexual partnerships • Inter-generational sex • Sexual coercion – gender norms • Vulnerability of couples Funding should track with transmission • Male circumcision

  22. HOUSEHOLD HIV PREVALENCE IN FRANCISTOWN, BOTSWANA 80 60 40 20 0 15-19 20-24 25-29 30-34 35-39 40-44 45-49 Male Female

  23. PERCENTAGE WHO KNOW RELATIVE/FRIEND WHO HAS DIED OF AIDS

  24. SEXUAL NETWORKING 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 • Fifth of population in mutually exclusive relationships • Two-thirds linked by single network over last three years • Networks not anchored by “high frequency transmitters” • Decentralized, complex, robust sexual chains

  25. 20 15 10 5 0 Male Female 30 25 20 15 10 5 0 Sex partner 5 or more years older Sex partner less than 5 years older PROPORTION OF 15 - 19 YEAR OLDS IN SOUTH AFRICA WITH SEX PARTNERS 5 OR MORE YEARS OLDER HIV PREVALENCE AMONG 15 - 19 YEAR OLDS IN SOUTH AFRICA WITH SEX PARTNERS 5 OR MORE YEARS OLDER

  26. 60% 50% 40% 30% 20% 10% 0% Guards Drivers Soldiers Police Seasonal workers SEXUAL PARTNERSHIPS IN SWAZILAND Casual sex Commercial sex SEXUAL PARTNERSHIPS IN LESOTHO 80% 60% 40% 20% 0% Soldiers Miners Drivers

  27. SEXUAL COERCION IN RAKAI, UGANDA HIV INCIDENCE IN RAKAI, UGANDA

  28. HIV PREVALENCE AND TRANSMISSION SOURCES IN ZAMBIA, 2005 Infections from sex work, clients, soldiers, truckers 50% 7% 14% 93% Infections from general population

  29. HIV PREVALENCE AND TRANSMISSION SOURCES IN ACCRA, GHANA, 2005 Adult male infections from general population 78% 24% 76% 2% Adult male infections from sex work

  30. HIV PREVALENCE, TRANSMISSION SOURCES AND FUNDING IN ACCRA, GHANA 99.2% 100% 78% 76% 80% 60% 40% 24% 20% 2.2% .08% 0% Sex workers General population HIV prevalence Transmission sources Funding

  31. BEHAVIORAL AND HIV TRENDS IN KENYA Males reporting multiple partners HIV prevalence 50 14 13 45 12 38 40 32 10 28 28 30 25 8 23 5.9 20 20 6 16 13 12 4 10 10 10 7 2 0 0 15-19 20-24 24-29 30-39 40-49 2006 2000 1993 1998 2003

  32. 16 14 40 12 30 10 1989 8 20 1995 6 10 4 2 0 Men with one or more casual partners in last year 0 Adult HIV prevalence 15 1991 35 16 15 1989 4.1 2003 15 6 3 1995 BEHAVIORAL AND HIV TRENDS IN UGANDA Percent reporting multiple partners HIV prevalence Women with one or more casual partners in last year Men with three or more casual partners in last year

  33. Circumcision and HIV Prevalence

  34. Effect size Study (95% CI) Overall 0.42 ( 0.34, 0.52) High-risk groups 0.29 ( 0.20, 0.42) General Population 0.56 ( 0.44, 0.71) South Africa 0.40 ( 0.24, 0.67) Kenya 0.41 ( 0.24, 0.70) Uganda 0.49 ( 0.28, 0.86) .15 .2 .3 .4 .5 1 1.5 Effect size Impact on HIV incidence: Evidence from observational studies and RCTs

  35. Evidence from RCTs

  36. FP Complements Other Programs to Reduce Infant Infections/Deaths Benefits of integrating family planning and nevirapine programs – annual projection of infections and deaths averted Source: USAID, 2003.

  37. HAS HIV INCIDENCE PEAKED IN AFRICA? HIV prevalence has fallen in several African countries – as the balance between HIV incidence, HIV prevalence and mortality shifts Incidence 3.1 million HIV – AIDS Prevalence 25.4 million Mortality 2.3 million

  38. Interventions that work • Male circumcision • ARVs! • Targeted interventions with BCC and condom promotion • ABCs • VCT • STI Rx and Dx • PMTCT and FP

  39. Important New Initiatives • PEPFAR • Gates Foundation (Buffett) • Global Fund for AIDS Malaria and TB

  40. Summary • Poor health effects women and children disproportionately • FP is a key intervention • ID extracts a huge burden on Africa and frustrates development • Generalized and concentrated HIV epidemics demand customized responses • AIDS taking a toll; new knowledge and large investments fuels hope