Parasitic infections in children: Case

This child has a soil-transmitted helminth infection, specifically hookworm, detected through routine refugee arrival screening. His iron-deficiency anaemia with a haemoglobin of 82 grams per litre and ferritin of 6 is the direct consequence of chronic occult blood loss from hookworm feeding on the intestinal mucosa, and his eosinophilia of 1.8 reflects the tissue migration phase of the larval life cycle. The Southeast Asian refugee camp exposure is the key epidemiological clue, and the screening stool microscopy is the confirmatory test. ^[2]

Clinical findings

The key findings are the profound iron-deficiency anaemia, the eosinophilia, and the hookworm ova on stool microscopy. The anaemia is the primary clinical concern and reflects months to years of low-grade intestinal blood loss from adult hookworms that attach to the small intestinal mucosa and feed on blood. Each adult worm consumes approximately 0.2 millilitres of blood per day, and a heavy burden over time produces significant iron depletion. The microcytic hypochromic picture with a very low ferritin confirms iron deficiency rather than anaemia of chronic disease. ^[2]

The eosinophilia is an expected finding in tissue-migrating helminths. Hookworm larvae penetrate the skin, travel via the bloodstream to the lungs, ascend the airways, and are swallowed before maturing in the small intestine. The pulmonary migration phase provokes eosinophilia, and the value of 1.8 is moderate and consistent with active tissue migration. The absence of respiratory symptoms in this child does not exclude pulmonary migration, because the larval burden may be too small to cause clinical Loeffler syndrome. ^[1]

The coinfection risk is important to consider. A child with hookworm from a tropical refugee setting is also at risk for other soil-transmitted helminths including Ascaris and Trichuris, and critically for Strongyloides stercoralis. Because this child is a refugee from Southeast Asia, the Strongyloides serology must also be checked, even if the initial stool does not show larvae, because stool microscopy for Strongyloides has low sensitivity due to intermittent and low larval output. ^[3]