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Review
. 2008 Apr;4 Suppl 1(Suppl 1):118-236.
doi: 10.1111/j.1740-8709.2007.00127.x.

A review and meta-analysis of the impact of intestinal worms on child growth and nutrition

Andrew Hall  1 , Gillian Hewitt, Veronica Tuffrey, Nilanthi de Silva
Affiliations
Review

A review and meta-analysis of the impact of intestinal worms on child growth and nutrition

Andrew Hall et al. Matern Child Nutr. 2008 Apr.

Abstract

More than a half of the world's population are infected with one or more species of intestinal worms of which the nematodes Ascaris lumbricoides, Trichuris trichiura and the hookworms are the most common and important in terms of child health. This paper: (1) introduces the main species of intestinal worms with particular attention to intestinal nematodes; (2) examines how such worms may affect child growth and nutrition; (3) reviews the biological and epidemiological factors that influence the effects that worms can have on the growth and nutrition of children; (4) considers the many factors that can affect the impact of treatment with anthelmintic drugs; (5) presents the results of a meta-analysis of studies of the effect of treating worm infections on child growth and nutrition; (6) discusses the results in terms of what is reasonable to expect that deworming alone can achieve; (7) describes some important characteristics of an ideal study of the effects of deworming; and (8) comments on the implications for programmes of recommendations concerning mass deworming.

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Figures

Figure 1
Figure 1
The proglottid of Taenia saginata (at the end of the stick) crawling away from a human stool in a trail of mucus. The sample was collected from a Pokot man in western Kenya, an ethnic group that traditionally enjoys eating undercooked beef (Hall et al. 1981).
Figure 2
Figure 2
The prevalence of infection with Ascaris lumbricoides in 11 age classes of males living in an urban slum in Dhaka, Bangladesh (data from Hall et al. 1999).
Figure 3
Figure 3
The typical relationship between the prevalence and the mean worm burden for intestinal nematode worms (see Guyatt et al. 1990). The shape of the curve is derived from data collected during a study of Ascaris lumbricoides in Bangladesh (Hall et al. 1999).
Figure 4
Figure 4
A diagrammatic representation of the proportions of a population of 100% who are infected with one, two or three types of worms when the prevalence of infection with Ascaris lumbricoides is 60%, Trichuris trichiura is 50% and hookworm is 40%. It is assumed that the probability of each infection is independent of each other and that probability of having two or more infections is multiplicative.
Figure 5
Figure 5
The average number of worms recovered from males in 11 age classes living in an urban slum in Bangladesh (Hall et al. 1999).
Figure 6
Figure 6
The distribution of Ascaris lumbricoides in 1765 people living in an urban slum in Dhaka, Bangladesh (Hall et al. 1999). The black line shows the negative binomial distribution.
Figure 7
Figure 7
The cumulative percentage of worms recovered from 1511 people infected with Ascaris lumbricoides in an urban slum in Bangladesh ranked according to worm burdens from zero to the maximum of 187 worms, plotted against the cumulative number of subjects from whom they were recovered (data from Hall et al. 1999).
Figure 8
Figure 8
The prevalence of infection with Ascaris lumbricoides at three rounds of treatment 6 months apart (Hall et al. 1992).
Figure 9
Figure 9
The mean worm burden with Ascaris lumbricoides at three rounds of treatment 6 months apart (Hall et al. 1992).
Figure 10
Figure 10
The prevalence of infection with Ascaris lumbricoides among 445 school‐age children in Bangladesh and the mean worm burden at baseline (0 months) and at two treatments 6 months apart (data from study of Hall et al. 1999). The dotted lines represent extrapolated trend lines if treatments had been given twice more at 6‐month intervals.
Figure 11
Figure 11
The average and 95% confidence intervals of body weight of two hypothetical groups of 300 children, one treated regularly with an anthelmintic and an untreated control group followed up for 3 years.
Figure 12
Figure 12
A conceptual model of the effect of worms on an outcome measure, and the need for remedial therapy after anthelmintic treatment to bring about a recovery.
Figure 13
Figure 13
The effects of treating intestinal worms on body weight (kg). To interpret the figure, see Section 5.3. CI, confidence intervals; PCD, Partnership for Child Development; WMD, weighted mean difference.
Figure 14
Figure 14
The effects of treating intestinal worms on height (cm). To interpret the figure, see Section 5.3. CI, confidence intervals; PCD, Partnership for Child Development; WMD, weighted mean difference.
Figure 15
Figure 15
The effects of treating intestinal worms on mid‐upper arm circumference (mm). To interpret the figure, see Section 5.3. CI, confidence intervals; PCD, Partnership for Child Development; WMD, weighted mean difference.
Figure 16
Figure 16
The effects of treating intestinal worms on triceps skinfold thickness (mm). To interpret the figure, see Section 5.3. CI, confidence intervals; PCD, Partnership for Child Development; WMD, weighted mean difference.
Figure 17
Figure 17
The effects of treating intestinal worms on z‐score of weight‐for‐age. To interpret the figure, see Section 5.3. CI, confidence intervals; WMD, weighted mean difference.
Figure 18
Figure 18
The effects of treating intestinal worms on z‐score of height‐for‐age. To interpret the figure, see Section 5.3. CI, confidence intervals; WMD, weighted mean difference.
Figure 19
Figure 19
The effects of treating intestinal worms on the difference in z‐score of weight‐for‐height. To interpret the figure, see Section 5.3. CI, confidence intervals; WMD, weighted mean difference.
Figure 20
Figure 20
The effects of treating intestinal worms on percentage of the median weight‐for‐age. To interpret the figure, see Section 5.3. CI, confidence intervals; WMD, weighted mean difference.
Figure 21
Figure 21
The effects of treating intestinal worms on percentage of the median height‐for‐age. To interpret the figure, see Section 5.3. CI, confidence intervals; WMD, weighted mean difference.
Figure 22
Figure 22
The effects of treating intestinal worms on percentage of the median weight‐for‐height. To interpret the figure, see Section 5.3. CI, confidence intervals; WMD, weighted mean difference.
Figure 23
Figure 23
The effects of treating intestinal worms on haemoglobin concentration (g dL−1). To interpret the figure, see Section 5.3. CI, confidence intervals; WMD, weighted mean difference.
Figure 24
Figure 24
The effects of treating intestinal worms on the dehydroretinol/retinol ratio expressed as a percentage. To interpret the figure, see Section 5.3. CI, confidence intervals; WMD, weighted mean difference.
Figure 25
Figure 25
A 2 × 2 factorial design to estimate the effect of deworming with or without a nutritional treatment or not.
Figure 26
Figure 26
The costs of anthelmintic treatment per child for a drug costing 3 US cents per child and the costs per infected child treated.
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