hookworms

Hookworms are parasitic nematodes that inhabit the small intestine of mammals, including humans. The two principal human hookworms are Necator americanus and Ancylostoma duodenale. They are classified as soil-transmitted helminths and are most common in tropical and subtropical regions with inadequate sanitation.

Life cycle and transmission

Eggs shed in feces hatch in warm, moist soil into filariform larvae (L3), which are the infectious form. Transmission occurs when larvae penetrate the skin, often through bare feet. After entry, larvae migrate via the bloodstream to the lungs, are swallowed, and mature into adults in the small intestine. Adults attach to the intestinal mucosa and feed on blood, producing eggs that are excreted in feces, continuing the cycle.

Clinical features

Light infections may be asymptomatic. Heavier infections can cause iron-deficiency anemia, protein malnutrition, fatigue, and pallor. Localized skin irritation or a “ground itch” at the entry site may occur. In children, hookworm can contribute to growth and cognitive development delays.

Diagnosis and treatment

Diagnosis is primarily by microscopic examination of stool for characteristic eggs. Serologic tests exist but are less commonly used. Treatment generally involves single or multi-day courses of antihelminthics such as albendazole, mebendazole, or ivermectin, with dosing depending on the drug and local guidelines. Anemia management may be required in cases of significant blood loss.

Prevention and public health

Prevention focuses on reducing transmission: wearing shoes to prevent skin contact with soil, improving sanitation and fecal disposal, and implementing deworming programs in endemic areas.