Epidemiologi Medicin 6.8. semester Global infections

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Epidemiologi Medicin - 6.-8. semesterGlobal
infections
Lektor Henrik Friis, PhD Afdeling for
Epidemiologi, Institut for Folkesundhedsvidenskab
h.friis_at_pubhealth.ku.dk
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Global infections

• Mortality, morbidity and disability
• The HIV pandemic
• Sentinel data
• Causes and effect modifiers
• HIV transmission current issues special
  designs
• Sexual transmission
• Mother-to-child tranmission

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Causes of death
(World Health and Disease by Alistair Gray, 2001)
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Causes of death
(WHO 1997, The World Health Report 1997
Conquering, suffering, enriching humanity)
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Causes of death in under-fives
(WHO 1997, The World Health Report 1997)
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Mortality, morbidity and disability
(WHO 1997, The World Health Report 1997)
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A global view of HIV infection in 1999
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AIDS Epidemic Updates
Tilgængelig december hvert år på UNAIDS
hjemmeside
http//www.unaids.org/worldaidsday/2002/press/Epiu
pdate.html
Dels som tekst, dels som PP-slide
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Changes in life expectancy in Africa
65
60
Botswana
Uganda
55
South-Africa
Life expectancy at birth, in years
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
Source United Nations Population Division, 1998
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Projected population in Botswana, 2020
80
Population in 2020
75
Males
Females
70
Deficits due to AIDS
65
60
55
50
Age in years
45
40
35
30
25
20
15
10
5
0
0
20
40
60
80
100
120
140
0
20
40
60
80
100
120
140
Population (thousands)
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Household production with AIDS, Zimbabwe

• Crops Reduction in
  output ()
• Maize 61
• Cotton 47
• Vegetables 49
• Groundnuts 37
• Cattle owned 29

Source Stover Bollinger, 1999
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TangaTZ.info http//208.184.18.238/tangatz/
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Sentinel data - HIV in pregnant women
The HIV prevalence in pregnant women declined
from 1990-98 in Uganda Does this reflect a
decline in incidence?
Source STD/AIDS Control Programme, Uganda
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Determinants of HIV in women
Basic Underlying Immediate
Political, cultural, religious, economic, and
social systems
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Co-infections interactions?

• Healthy adults at Ukerewe Island, Tanzania
  (N1000)

Malenganisho W, unpublished
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Co-infections interactions?

• Adult TB patients in Mwanza, Tanzania (N655)

Range N, unpublished
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Kamali A, Lancet, 2003
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Mother-to-child HIV transmission

• Transmission rate
• Developed countries 15-25
• Developing countries 25-35
• Route
• Intrauterine 6
• Intrapartum 14
• Postnatally 14-29

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Potential risk factors

• Maternal
• High viral load - primary or advanced infection
• Genital tract infections, breast inflammation and
  cracked nipples
• Sex and drug use in pregnancy
• Vitamin A deficiency or supplementation
• Obstetric
• Prolonged rupture of membranes
• Bacterial vaginosis and chorioamnionitis
• Vaginal delivery
• Invasive obstetric procedures
• Fetal/infant
• Prematurity
• Mode of feeding

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Vitamin A and HIV infectionObservational studies

• Vitamin A deficiency a strong predictor of
• virus in breast milk and genital secretions
• (Nduati R, J Inf Dis, 1995 John, J Inf Dis,
  1997)
• mother-to-child transmission
• (Semba R, Lancet, 1994)

Do we have sufficient evidence to implement a
vitamin A supplementation programme to pregnant
HIV women?
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Vitamin A and early vertical transmission of
HIVIntervention trials

• Malawi
• no effect of vitamin A
• (Semba R, unpublished)
• South Africa
• no effect of vitamin A/?-carotene
• may reduce transmission in preterm deliveries
• (Coutsoudis A, 2000)
• Tanzania
• no effect of vitamin A/?-carotene or
  multivitamins
• (Fawzi WW, 2000)

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The Tanzania Vitamin TrialA two-by-two factorial
trial

• 1075 HIV pregnant women in Tanzania
• Randomized, controlled trial with two
  interventions
• Vitamin A or placebo
• Multivitamins or placebo
• Results
• Multivitamins RR (95 CI) change
• Fetal loss 0.61 (0.39-0.94) -39
• Small for gestational age 0.57
  (0.39-0.82) -43
• Preterm birth (lt34 wks) 0.61
  (0.38-0.96) -39
• CD4 counts 10
• Vitamin A No effects
• (Fawzi WW, Lancet, 1998)

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The Tanzania Vitamin TrialA two-by-two factorial
trial
Vitamin A
Hvis ingen interaktion / effect modifikation, så
kan man se på effekten af en intervention,
uafhængigt af den anden
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Vitamins and HIV transmissionTanzania Vitamin
Trial
Higher transmission in vitamin A supplemented

• Effects on HIV transmission
• Vitamin A
• RR 1.38 (1.09 1.76)
• Multivitamins
• RR 0.85 (061 1.19)
• In women with low CD4
• RR 0.37 (0.16 0.85)
• (Fawzi WW, AIDS, 2002)

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Sub-clinical mastitis and HIV transmission?

• Sub-clinical mastitis
• -
• Viral load Low High
• Babies with HIV at 6 wks 23 45
• Babies with HIV at 12 mo 26 51
• Semba R, 1999

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Infant feeding and HIV

• 549 HIV pregnant women enrolled in South Africa
• Mode of feeding assessed prospectively
• Mother-to-child HIV transmission determined at 3
  mo

TR RR (95 CI)
Mixed feeding 24.1 1 Exclusive breast
feeding 14.6 0.52 (0.28 0.98) Formula
feeding 18.8 0.85 (0.51 1.42)
Coutsoudis A, Lancet, 1999