Transcript Helminth infections, growth and anemia: lessons

Helminth Infections in < 2 yr
• Currently no recommendation to deworm
children in this age group
– Only rec. for preschoolers is regarding Rx of
severe anemia, then recommended for > 2 yr.
(WHO/UNICEF/INACG, 1998)
Drugs and < 2 yr
• Wary of using drugs in this age group
• Recent WHO consultation on use of
benzamidazole drugs in < 2 yr (March 02)
– Jannsen (maker of mebendazole) states that
drug may be used in children 0-2 yr if the
helminth infection is deemed to affect health or
nutrition of child.
– SKB (maker of albendazole) does not
recommend use < 12 mo.
Initial expectations
transmission
of helminth
infection
worm burden
Malabsorption
GI blood loss
Chemical
messages to
host
Poor
growth
Iron-def.
anemia
Geohelminth and P. falciparum
infections by age
Prevalence of infection (%)
100
90
80
Hookworms
70
Trichuris
60
50
Ascaris
40
30
Malaria
20
10
0
<1
1
2
3
Age (yr)
4
5
Mean Hb and prevalence of severe
anemia at baseline
Prevalence of Hb < 7 g/dL
Mean Hb (g/dL)
35
10
30
9
25
8
20
15
7
10
6
5
0
5
<1
1
2
3
Age (yr)
4
5
<1
1
2
3
Age (yr)
4
5
Haemoglobin < 90 g/L (%)
70
60
Mebendazole
Placebo
50
40
30
20
10
0
<24
24-47
>47
Age (months)
Change in serum ferritin (ug/L)
70
60
Mebendazole
Placebo
50
40
30
20
10
0
<24
24-47
>47
Age (months)
Revised expectations (2)
transmission
of helminth
infection
accumulation
of worm
burden
Malabsorption
GI blood loss
Chemical
messages to
host
Poor
growth
age
inflammatory (i.e.
cytokine) response of
the "naive" host
Iron-def.
anemia
altered
metabolism
suppressed
appetite
"Anemia of
chronic
disease"
Implications of revised model
Geohelminths may cause malnutrition
through two distinct pathways
The "worm burden" pathway:
Predominates in semi-immune individuals.
Substantial effect on iron deficiency anemia
Small effect on growth
Implications of revised model
(continued)
The "inflammation" pathway:
Predominates in non-immune individuals
Substantial effects on "anemia of chronic
disease"
Substantial effects on wasting malnutrition
The importance of these pathways depends
on the age of the target population, the
intensity of transmission, and perhaps the
worm species present.
Investigative teams
Schoolers
Hababu M. Chwaya
Rebecca Stoltzfus
Marco Albonico
Kassim S. Alawi
Lorenzo Savioli
Jim Tielsch
Preschoolers
Hababu M. Chwaya
Jape K. Jape
Rebecca Stoltzfus
Antonio Montresor
Jim Tielsch
Marco Albonico
Lorenzo Savioli
Jane Kvalsvig
Ernesto Pollitt