Tropical Parasitology

: 2011  |  Volume : 1  |  Issue : 2  |  Page : 50--51

Intestinal parasites in Indian children: A continuing burden

John Philip Ackers 
 Department of Pathogen Molecular Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom

Correspondence Address:
John Philip Ackers
Department of Pathogen Molecular Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London
United Kingdom

How to cite this article:
Ackers JP. Intestinal parasites in Indian children: A continuing burden.Trop Parasitol 2011;1:50-51

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Ackers JP. Intestinal parasites in Indian children: A continuing burden. Trop Parasitol [serial online] 2011 [cited 2022 Jul 4 ];1:50-51
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Two reports in the current issue of Tropical Parasitology[1],[2] report a worryingly high prevalence of intestinal parasites (protozoa and helminths) in two populations of Indian children. Apart from the differences in the prevalence of hookworm, much the same organisms are present in both groups, and the figures are not noticeably better than those reported in the past. The effect of long-term infection with these parasites on the children's physical and mental development is clearly harmful and emphasize the need to develop affordable methods of control.

This issue of Tropical Parasitology contains two reports [1],[2] examining the prevalence of intestinal parasites (protozoa and helminths) in Indian children. Both employ a similar methodology - fecal samples were collected in the children's homes either in the presence of the investigators or brought to school the following day. Examination has been done using the standard light microscopical techniques.

One limitation, recognized by the authors, was that it was not possible to examine the samples sufficiently soon after they were passed, to detect the motile protozoan trophozoites. The significance of this was that this is the only low-cost way of differentiating the invasive Entamoeba histolytica (where trophozoites contain ingested red blood cells) from the non-pathogenic amoeba with identical cysts - specifically Entamoeba dispar and Entamoeba moshkovskii. Therefore, it was possible, and indeed likely, that most of the children apparently infected with E. histolytica were actually infected with one of the other non-pathogenic species. [3] The question of how these infections should be reported is a difficult one. In 1997, the World Health Organization (WHO) [4] recommended the use of the term E. histolytica / dispar - but this was when infections with E. moshkovskii were virtually unknown. Subsequently, however, they have been found in very significant numbers of children in Bangladesh [5] and Tanzanian HIV patients, [6] and with a lower prevalence, in many other populations. It would now be technically correct to report all diagnoses, made only by examination of cysts, as E. histolytica / dispar / moshkovskii, but many feel this is already too clumsy - and how many other identical species are waiting to be discovered?

Returning to the two studies, both clearly demonstrate two worrying facts - that intestinal parasitic infections are common in young Indian children, and that the poorer and more disadvantaged these children's home circumstances are, the more likely they are to be infected. It is very difficult to compare the earlier surveys from other populations in other areas, but there is no real evidence that the situation has significantly improved over time. It is, however, encouraging that Shubha, et al., 2011, [1] found that older children were less likely to be infected than younger ones. This result is commonly found in the case of infections with Giardia intestinalis in endemic areas, where it is attributed to developing immunity, but the finding that it applies to all intestinal parasitic infections is interesting and the authors' suggestion that this is due to improved hygiene practices should be further investigated. The organisms most frequently detected were similar in both studies (E. histolytica / dispar / moshkovskii and Giardia intestinalis among the protozoa and Ascaris lumbricoides, Enterobius vermicularis, and Trichuris trichiura among the helminths) - but with one significant difference. Although only 3% of children in Ghaziabad were infected with hookworm, [2] in Chitradurg 28% were infected . [1] This is significant, as hookworm infection can definitely cause anaemia [7] - although other common soil transmitted helminths have also been implicated. [8]

How detrimental are these infections to the growing child's development? There is good evidence that repeated enteric infections, usually but not always linked to attacks of diarrhea, can lead to malnutrition, with long-term adverse effects on development. [9] Not surprisingly, it has proved much harder to link these effects to one specific pathogen, and results (which will not be discussed here) have been contradictory; but the Giardia and Cryptosporidium species have been regarded as the protozoa most likely to affect development. In contrast there is a broad consensus that the soil-transmitted helminths (Ascaris, Trichuris, and the two hookworms - Ancylostoma duodenale and Necator americanus) have a harmful effect on children's growth and cognitive development [10] and they have for this reason been included in the World Health Organization's Neglected Tropical Diseases initiative. [11]

Control of all intestinal parasites in resource-poor settings is challenging. Optimally, the provision of clean drinking water and the safe disposal of feces will interrupt transmission and a recent investigation of the impact of large-scale sewer construction (in Brazil, not India) showed it to be effective in reducing the prevalence of Ascaris, Trichuris, and Giardia[12] - but schemes like this are often unaffordable where they are most needed. As an alternative, mass deworming of schoolchildren and others is now recommended by the World Health Organization - 'The strategy for soil-transmitted helminthiasis control is to treat once or twice per year, preschool and school-age children; women of childbearing age (including pregnant women in the second and third trimesters and lactating women), and adults at high risk, in certain occupations (e.g., tea-pickers, miners, etc.)". [13] Progress has been made, but global coverage is nowhere near the target of treating 100% of schoolchildren by 2010. [14] In addition, controversies [15] continue, concerning the long-term sustainability of mass deworming - might not sanitary engineering be cheaper in the long run and confer many other health benefits? A recent meta-analysis [16] depressingly concluded, 'Deworming drugs used in targeted community programs may be effective in relation to weight gain in some circumstances, but not in others. No effect on cognition or school performance has been demonstrated', although it has been convincingly argued that this is the result of asking the wrong question in the wrong manner. [17] Whatever the best approach is, studies like the ones reported here are needed to remind us of the ubiquity of intestinal parasites and the need to make real progress in reducing this burden on our children's physical and mental development.


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