Infectious Disease in Africa:Infectious Disease in Africa:lessons learned and their application lessons learned and their application

Michael Welsh, Ph.D.

TopicsTopics

Population structure and public health challenges

Infectious disease

HIV Epidemiology

Lessons learned in HIV prevention

Population of Sub-Saharan Africa Population of Sub-Saharan Africa by Age and Sex: 2000 to 2005by Age and Sex: 2000 to 2005

Source: U.S. Bureau of Census.

MaleMale FemaleFemale

Age group < 15 represents 44%

of the total population

Fertility Decline in Selected World Fertility Decline in Selected World Regions, Early 1960s to 2005Regions, Early 1960s to 2005

6.7

5.8

6.7

6.0

2.7

2.5

2.5

1.6

5.4

3.0

2.74.6

0 1 2 3 4 5 6 7 8

Latin America

Asia

Sub-Saharan Africa

Developingcountries

Developedcountries

WorldEarly 1960s

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.

Use and Total Unmet Need* Use and Total Unmet Need* Women 15-49Women 15-49

0

10

20

30

40

50

60

Use Total Unmet Need

Source: Demographic and Health Surveys.

*All women 15-49, modern methods. **Currently married women 15-49, modern methods.

177.7166

155

142 142

125.2117

106 10498

52

185.9

102

6859

105102.3 99 95 91

66 64.467

59

0

20

40

60

80

100

120

140

160

180

200

Mal

i 19

96

Ethio

pia 2

000*

Mal

awi 2

000*

Burki

na Fas

o 199

9

Guinea

199

9

Togo 1

998

Uganda

2000

/01

Camer

oon 1

998

Ghana

1998

Niger

ia 1

999

Kenya

199

8

Seneg

al 1

997

Dea

ths

per

1,0

00 i

nfa

nts

un

der

ag

e o

ne

Less than two years At least 2 years

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.

Source: Country DHS Reports.* Figures here are only for a 2 year birth interval instead of a 2-3 year interval.

Traditional Epidemiological Framework

Agent

Host

Env

iron

men

t

Disease

Source: Center for Health and the Global Environment, Harvard Medical School

LeadingLeading causes of death causes of death in Africa, 2000in Africa, 2000

Source: The World Health Report 2001, WHO

22.6

10.1 9.16.7

5.5 4.3 3.6 3.1 2.9 2.3

0.0

5.0

10.0

15.0

20.0

25.0

HIV/AIDS Malaria Perinatalconditions

Tuberculosis

Cerebrovascular disease

Diarrhoeal disease

Lowerrespiratory infections

Measles Ischaemic Heart

disease

Maternalconditions

% ofTotal

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

62

31

11 105

0

10

20

30

40

50

60

70

Africa SE Asia Western Pacific Americas Europe

QuestionQuestion

Why do you think that Africa has such a serious problem

with ID?

Factors that contribute to infectious Factors that contribute to infectious disease in Africadisease in Africa

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

Per capita gross national income by regionPer capita gross national income by region(US $) (US $)

0

500

1000

1500

2000

2500

3000

3500

4000

SSA South Asia LatinAmerica

East Asiaand thePacific

MiddleEast and

NorthAfrica

Source: Sachs J. et al., Ending Africa’s Poverty Trap, Brookings Institution, 2004

Health Expenditures per CapitaHealth Expenditures per Capita

$19 $31 $10$230

$18 $36

$4,271

Ghana Kenya Rwanda South Africa Uganda Zimbabwe United States

Physicians per 100,000 people: 1990-2002Physicians per 100,000 people: 1990-2002

263 6 14 5 4

19 10

276

0

50

100

150

200

250

300

Source: Human Development Report 2003New York: Oxford University Press, 2003

Measles coverage at 1 yearMeasles coverage at 1 year

0102030405060708090

100

1980 1990 1999

World

SSA

China

India

World Development Indicators, World Bank, 2002

Nutritional DeficitsNutritional 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

Access to Improved Water SourcesAccess to Improved Water Sources

87 87

60

92

72

100 100

49

31

40

80

46

77

100

0

10

20

30

40

50

60

70

80

90

100

Ghana Kenya Rwanda SouthAfrica

Uganda Zimbabwe UnitedStates

Urban

Rural

Source: USAID (2002)

AIDS MortalityAIDS Mortality

Cumulative mortality in USthru Dec 2001

Mortality in sub-Saharan Africain a single year, 2002

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

3,000,000

15-35%3-7%1-5%0-0.1%

HETEROGENEITY OF HIV IN AFRICA

HETEROGENEITY OF HIV IN AFRICAHETEROGENEITY OF HIV IN AFRICAA TALE OF THREE EPIDEMICSA TALE OF THREE EPIDEMICS

Manzini, Swaziland

Kampala, Uganda

Dakar, Senegal05

101520253035404550

86 88 90 92 94 96 98 00 02 04

PREVENTION LESSONS FROM PREVENTION LESSONS FROM GENERALIZED EPIDEMICSGENERALIZED EPIDEMICS

StigmaConcurrent sexual partnershipsInter-generational sexSexual coercion – gender normsVulnerability of couples

Funding should track with transmissionMale circumcision

HOUSEHOLD HIV PREVALENCE IN FRANCISTOWN, HOUSEHOLD HIV PREVALENCE IN FRANCISTOWN, BOTSWANABOTSWANA

0

20

40

60

80

15-19 20-24 25-29 30-34 35-39 40-44 45-49

Male Female

PERCENTAGE WHO KNOW RELATIVE/FRIEND PERCENTAGE WHO KNOW RELATIVE/FRIEND WHO HAS DIED OF AIDSWHO HAS DIED OF AIDS

8574 71

66 61 57

3627

18 1811

0

20

40

60

80

100

SEXUAL NETWORKING IN LIKOMA,MALAWISEXUAL NETWORKING IN LIKOMA,MALAWI

Sourc

e:

Kohle

r H

and

Helle

ring

er

S. The S

truct

ure

of

Sexual N

etw

ork

s and

the S

pre

ad

of

HIV

in S

ub

-Sahara

n A

fric

a:

Evid

ence

fro

m L

ikom

a Isl

and

(M

ala

wi)

. PA

RC

Work

ing

Pap

er

Seri

es:

W

PS

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

PROPORTION OF 15 - 19 YEAR OLDS IN SOUTH AFRICAWITH SEX PARTNERS 5 OR MORE YEARS OLDER

0

5

10

15

20

Male Female

HIV PREVALENCE AMONG 15 - 19 YEAR OLDS IN SOUTH AFRICA

WITH SEX PARTNERS 5 OR MORE YEARS OLDER

0

5

10

15

20

25

30

Sex partner 5 or more years older Sex partner less than 5 years older

SEXUAL PARTNERSHIPS IN SWAZILANDSEXUAL PARTNERSHIPS IN SWAZILAND

0%10%20%30%40%50%60%

Guards Drivers Soldiers Police SeasonalworkersSEXUAL PARTNERSHIPS IN LESOTHOSEXUAL PARTNERSHIPS IN LESOTHO

0%

20%

40%

60%

80%

Soldiers Miners Drivers

Casual sexCommercial sex

SEXUAL COERCION IN RAKAI, UGANDA

0

5

10

15

20

25

30

35

At firstsex

By 19 By 24 Allwomen

HIV INCIDENCE IN RAKAI, UGANDA

0

0.5

1

1.5

2

Coercivefirst sex

Coercivesubsequent

sex

Nevercoerced

HIV PREVALENCE AND TRANSMISSION SOURCES IN ZAMBIA, 2005HIV PREVALENCE AND TRANSMISSION SOURCES IN ZAMBIA, 2005

0

10

20

30

40

50

Adult HIV+ Sex worker HIV

Infections from sex work,clients, soldiers, truckers

Infections fromgeneral population

93%

7%

50%

14%

HIV PREVALENCE AND TRANSMISSION SOURCES IN ACCRA, HIV PREVALENCE AND TRANSMISSION SOURCES IN ACCRA, GHANA, 2005GHANA, 2005

0

20

40

60

80

Adult HIV+ Sex worker HIV Adult male infectionsfrom sex work

Adult male infectionsfrom general population

2%

78%

24%

76%

HIV PREVALENCE, TRANSMISSION SOURCES AND FUNDING IN HIV PREVALENCE, TRANSMISSION SOURCES AND FUNDING IN ACCRA, GHANAACCRA, GHANA

78%

2.2%

76%

24%

.08%

99.2%

0%

20%

40%

60%

80%

100%

Sex workers General population

HIV prevalence Transmission sources Funding

BEHAVIORAL AND HIV TRENDS IN KENYABEHAVIORAL AND HIV TRENDS IN KENYA

0

2

4

6

8

10

12

1445

3228

2523

38

28

20

107

1613 12

10

0

10

20

30

40

50

15-19 20-24 24-29 30-39 40-49

1993 1998 2003 2000 2006

13

5.9

Males reporting multiple partners

HIV prevalence

Percent reporting multiple partners

BEHAVIORAL AND HIV TRENDS IN UGANDABEHAVIORAL 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 last year

Women with one or more casual

partners in last year

Men with three or more casual

partners in last year

0

2

4

6

8

10

12

14

16

1991 15

2003 4.1

Adult HIV prevalence

HIV prevalence

Circumcision and HIV PrevalenceCircumcision and HIV Prevalence

Impact on HIV incidence: Impact on HIV incidence: Evidence from observational studies and RCTsEvidence from observational studies and RCTs

Effect size .15 .2 .3 .4 .5 1 1.5

Study

Effect size

(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)

Evidence from RCTsEvidence from RCTs

Site Population Effect

Orange Farm, SA 18 -24 60 %

Rakai, Uganda 15 – 49 48 %

Kisumu, Kenya 18 – 24 53 %

FP Complements Other Programs to Reduce FP Complements Other Programs to Reduce Infant Infections/DeathsInfant Infections/Deaths

Source: USAID, 2003.Source: USAID, 2003.

Benefits of integrating family planning and nevirapine programs – annual projection of infections and deaths averted

0

20,000

40,000

60,000

80,000

Nevirapine alone FP plus nevirapine

Child infections averted

Child deaths averted

HIV – AIDSPrevalence25.4 million

Incidence3.1 million

Mortality2.3 million

HAS HIV INCIDENCE PEAKED IN AFRICA? 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

Interventions that workInterventions that work

Male circumcision

ARVs!

Targeted interventions with BCC and condom promotion

ABCs

VCT

STI Rx and Dx

PMTCT and FP

Important New InitiativesImportant New Initiatives

PEPFAR

Gates Foundation (Buffett)

Global Fund for AIDS Malaria and TB

SummarySummary

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