Helminths and Deworming in Children
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Direct answer
Soil-transmitted helminths — roundworm (Ascaris lumbricoides), hookworm (Ancylostoma duodenale and Necator americanus) and whipworm (Trichuris trichiura) — chronically infect hundreds of millions worldwide, with Indian children carrying one of the largest burdens; the pinworm (Enterobius vermicularis) adds the commonest helminth of the urban middle-class child. The clinical logic is organ-based: Ascaris causes intermittent obstruction, malnutrition and Loeffler's eosinophilic pneumonitis during larval migration; hookworm causes iron-deficiency anaemia through luminal blood loss; Trichuris causes the dysentery-rectal-prolapse syndrome; Enterobius causes nocturnal perianal pruritus and is diagnosed by cellulose tape, not stool. Treatment is single-dose albendazole 400 mg (200 mg below two years), the same tablet that powers India's National Deworming Day each February 10 with a mop-up round, delivered through schools and Anganwadis to children aged 1 to 19 years.
What you must remember
- Ascaris lumbricoides: the largest intestinal nematode (15 to 35 cm), acquired via ingestion of embryonated eggs; larval migration through the lungs produces Loeffler syndrome — cough, wheeze, transient infiltrates with eosinophilia; adult worms cause abdominal pain, malnutrition and small-bowel or biliary obstruction.
- Hookworm: larvae penetrate the skin of bare feet ("ground itch"); Ancylostoma and Necator attach to duodenal mucosa and sip blood — the classic cause of iron-deficiency anaemia and hypoproteinaemia in an Indian schoolchild who eats adequately; deworming belongs in every refractory iron-deficiency workup.
- Trichuris trichiura: heavy worm loads cause the Trichuris dysentery syndrome — chronic bloody mucoid diarrhoea, tenesmus, and rectal prolapse with worms visible on the prolapsed mucosa; treat with albendazole for three days plus iron.
- Enterobius vermicularis: nocturnal perianal pruritus, sleep disturbance, occasionally vulvovaginitis; eggs are laid on perianal skin at night, so diagnosis is the cellulose (Scotch) tape test in the morning — stool examination is often negative; treat the whole family with albendazole or mebendazole and repeat after two weeks because eggs re-infect via hands.
- Dose sheet: albendazole 400 mg single dose (200 mg for 1 to 2 year olds) for Ascaris, hookworm and Enterobius; mebendazole 100 mg twice daily for three days (or 500 mg once) as the alternative; ivermectin 200 micrograms/kg for strongyloidiasis, where the autoinfection cycle persists for decades and hyperinfection erupts when corticosteroids or HTLV-1 co-infection depress immunity; praziquantel 40 mg/kg for schistosomiasis and tapeworms.
- National Deworming Day: February 10 each year with a mop-up round on August 10 in many states — a single 400 mg albendazole chewable to all children aged 1 to 19 years through schools and Anganwadi centres, among the largest public health programmes in the world, because chronic helminths impair growth, cognition and school attendance and WHO recommends periodic deworming where prevalence exceeds 20 per cent.
From symptom to worm to drug
Picture three children in one week of clinic. The first, a four-year-old with pica and pallor, has haemoglobin 7.8 g/dL with a hypochromic microcytic film; she walks barefoot in a village lane. Stool shows hookworm ova. Her treatment has three arms — albendazole 400 mg now (repeat in some schedules), oral iron for three months to refill stores, and footwear advice; her "refractory" anaemia was never refractory, simply never dewormed.
The second, a six-year-old urban boy from a good home, wakes nightly scratching; the mother has seen "white threads". The morning tape test shows the characteristic asymmetric ovoid eggs. Albendazole goes to the whole family — including the asymptomatic father — with a repeat dose after two weeks, plus nail-trimming and morning washing of bed linen, because autoinfection through scratched perianal skin is the engine of this infection.
The third, a wheezing eight-year-old with eosinophils at 35 per cent and fleeting chest infiltrates, has no stool ova yet — the larvae are migrating. This is Loeffler syndrome; albendazole follows, and the asthma label is quietly retired.
How the exam frames it
Matching questions dominate: worm to complication — Ascaris to intestinal obstruction and Loeffler, hookworm to iron-deficiency anaemia, Trichuris to rectal prolapse, Enterobius to perianal pruritus with a negative stool report, Strongyloides to hyperinfection under steroids. The programme question is guaranteed marks: National Deworming Day, February 10, albendazole 400 mg for 1 to 19 years (halved below two years), school-and-Anganwadi delivery. The subtle trap is the eosinophil question — tissue-invasive helminths (and migration phases) raise eosinophilia, but Enterobius and Trichuris typically do not meaningfully; and corticosteroid therapy in a child with unexplained eosinophilia should prompt a Strongyloides thought before the first dose is drawn.
Frequently asked questions
What is the dose of albendazole used in mass deworming?
A single 400 mg chewable tablet for children aged 2 to 19 years and 200 mg for those aged 1 to 2 years, repeated per programme schedule.
Which helminth causes iron-deficiency anaemia in children and by what mechanism?
Hookworm — larvae enter through the skin and adult worms suck blood from the duodenal mucosa, producing chronic iron loss.
How is Enterobius vermicularis best diagnosed?
By the morning cellulose tape test applied to the perianal skin, demonstrating the characteristic eggs; stool examination is frequently negative.
What is Loeffler syndrome?
Transient pulmonary infiltrates with cough, wheeze and marked eosinophilia caused by larval migration of Ascaris (also hookworm or Strongyloides) through the lungs.
When does Strongyloides hyperinfection occur?
During immunosuppression, especially corticosteroid therapy or HTLV-1 co-infection, when the autoinfection cycle amplifies into disseminated, often fatal disease; ivermectin is the treatment of choice.