Helminth Infections in Neonates and Young Children

Helminth Infections

The preceding answer choices represent, in descending order, the 5 most prevalent helminth infections worldwide: ascariasis, trichuriasis (or whipworm), hookworm, schistosomiasis, and lymphatic filariasis.^[2] Of these, only hookworm is typically associated with such profound anemia.

Although more prevalent in older children, hookworm has been described in infants. In the case series from which this vignette was adapted, each infant presented with melena and anemia. Owing to the young presentation, other diagnoses were considered first. Ultimately, Ancylostoma were discovered on esophagogastroduodenoscopy. The infant's anemia, melena, and eosinophilia improved after treatment with albendazole.^[1]

Broadly, the term "helminth" refers to parasitic worms that can be classified into 2 phyla: Nematoda (roundworms) and Platyhelminthes (flatworms). The phylum Platyhelminthes is further divided into Cestoda (tapeworms) and Trematoda (flukes).

Helminthiasis is a major public health threat throughout Asia, sub-Saharan Africa, and the Americas. It has been estimated that more than 1 billion people worldwide are infected with at least 1 species, and many are coinfected with 2 or more parasites.^[3,4] Most of those affected represent the world's poorest and most vulnerable populations. Economist Paul Collier has termed this population "the bottom billion." Poor access to healthcare, sanitation, and clean water make this group particularly susceptible to infection.

This article will discuss how helminth infections affect arguably the most vulnerable group of all: neonates and young children.

Hookworm

In this first case, both EB and his mother demonstrate consequences of hookworm infection. Two species of hookworm cause disease in humans. Necator americanus is found in the Americas, sub-Saharan Africa, and parts of Asia. A duodenale occurs in the Mediterranean, parts of the Middle East, and Asia. Between 740 million and 1.3 billion people worldwide are probably infected.^[2,5]

Hookworm eggs are found in soil contaminated with feces. The larvae hatch, develop in the soil, and penetrate the skin of a human host. As the larvae migrate through the host's skin, a pruritic rash may erupt. The larvae then travel through the bloodstream to the lungs, where they penetrate the alveoli and are swallowed by the host. They mature in the small intestine, where the main manifestations of disease occur. The parasite's mouthpiece contains sharp hooks for attaching to the duodenal wall. Once attached, hookworms release anticoagulant peptides and serine proteinase inhibitors, which contribute to anemia and malabsorption of nutrients, respectively.

After attachment, a single worm may consume 0.3-0.5 mL of blood per day.^[6,7] Heavy infection can therefore result in profound anemia as well as protein loss, leading to malnutrition and anasarca. In endemic areas, coinfection with multiple types of helminthes is common and increases nutritional losses (Figure).

Figure. Life cycle of the hookworm. Image courtesy of the Centers for Disease Control and Prevention (https://www.cdc.gov/parasites/hookworm/biology.html)

Cite this: Helminth Infections in Neonates and Young Children - Medscape - Jun 25, 2014.

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