In United States, hookworm Infection is managed by tropical medicines. Hookworm infection is a chronic intestinal parasitism caused by the blood-feeding nematodes Necator americanus and Ancylostoma duodenale (and rarely Ancylostoma ceylanicum), acquired when infective larvae penetrate intact skin during contact with fecally-contaminated soil. The World Health Organization estimates 472-740 million people are infected globally, concentrated in low-income tropical and subtropical regions with poor sanitation.
Hookworm infection (ICD-10: B76) is a soil-transmitted helminth infection caused by Necator americanus (the dominant species in the Americas, sub-Saharan Africa, Southeast Asia, and the Pacific) or Ancylostoma duodenale (in the Middle East, North Africa, India, and southern Europe historically), and occasionally Ancylostoma ceylanicum (Southeast Asia, an emerging zoonotic and human-adapted species). The life cycle begins when infective filariform (L3) larvae in warm, moist soil penetrate human skin — typically through the dorsum of the foot during barefoot walking. Larvae enter the venous circulation, traverse the right heart and pulmonary capillaries, ascend the bronchial tree, are swallowed, and mature in the small intestine where adult worms (8-13 mm) attach to villi using cutting plates (Necator) or teeth (Ancylostoma). Adult females release 5,000-30,000 eggs per day passed in feces; eggs hatch into rhabditiform larvae in soil and mature to filariform larvae within 5-10 days.
The key symptoms of Hookworm Infection are: Intense pruritic, erythematous papular eruption (ground itch) at the site of larval skin penetration, usually on the dorsum of the foot, within minutes to hours of soil contact., Migratory wheezing, cough, and low-grade fever during pulmonary larval migration 1-2 weeks after exposure — Löffler-like syndrome with peripheral eosinophilia and transient infiltrates on chest imaging., Vague upper abdominal pain, nausea, anorexia, and intermittent diarrhea 4-6 weeks after infection as adult worms establish in the small intestine., Progressive fatigue, exertional dyspnea, pallor, and reduced exercise tolerance from iron-deficiency anemia in moderate-to-heavy chronic infection., Geophagia (pica for earth), pagophagia (ice craving), and koilonychia (spoon-shaped nails) in long-standing iron deficiency., Growth faltering, stunting, and impaired cognitive performance in chronically infected school-age children., Edema (pedal and periorbital) from hypoalbuminemia in very heavy infections or chronically malnourished hosts..
Diagnosis combines exposure history, peripheral blood count showing eosinophilia with iron-deficiency anemia, and microscopic identification of characteristic eggs on stool examination. Hookworm eggs (60-75 µm, thin-shelled, oval, with 4-8 cell morula or fully developed larva by the time stool reaches the lab) are indistinguishable between Necator and Ancylostoma on routine microscopy; PCR or larval culture is required for species identification. The WHO-recommended Kato-Katz thick smear quantifies egg burden (eggs per gram of feces) and stratifies severity: light <2,000 epg, moderate 2,000-3,999, heavy ≥4,000. Multiple stool samples on consecutive days substantially improve sensitivity in light infection. PCR-based assays (multiplex PCR for soil-transmitted helminths) have become the most sensitive method and now distinguish species, including Ancylostoma ceylanicum. Peripheral blood eosinophilia (often 500-3,000/µL) is common but non-specific. Iron studies (low serum ferritin, low transferrin saturation, microcytic hypochromic indices) and stool occult blood support the diagnosis of chronic blood loss. Differential diagnosis includes other soil-transmitted helminths (Ascaris, Trichuris, Strongyloides), schistosomiasis, malaria-related anemia, nutritional anemia, and inflammatory bowel disease. WHO-recommended diagnostic workflow in endemic areas focuses on stool microscopy and population-level screening; in returning travelers from tropical regions, screening also covers schistosomiasis and Strongyloides.
Prognosis is excellent with appropriate treatment. A single dose of albendazole 400 mg cures 72-80% of infections and reduces egg burden by 89-95%; persistent egg-positivity responds to repeat dosing or extended (3-day) regimens. Iron-deficiency anemia recovers fully when both parasite and iron deficiency are treated, with hemoglobin rising 1-2 g/dL within 4-8 weeks and full iron-store replenishment over 3-6 months. Growth catch-up in chronically infected children occurs within 6-24 months of effective treatment. The dominant long-term challenge in endemic settings is re-infection: without sanitation improvement and shoe-wearing, prevalence and worm burdens return toward pre-treatment levels within 6-18 months. WHO-supported mass drug administration of school-age children sustains lower community burdens but does not eliminate transmission. Drug resistance, while well-established in veterinary parasitology, remains uncommon but is monitored as an emerging concern in human STH programs. Travelers and migrants from endemic regions, with no further exposure, are usually cured by a single course of albendazole and remain disease-free.
Most uncomplicated hookworm infection is managed by primary-care and pediatric services using single-dose albendazole and iron. Tropical medicine or infectious disease referral is appropriate for atypical presentations, suspected drug resistance, returning travelers with co-infections (schistosomiasis, Strongyloides, malaria), or severe complications including symptomatic anemia and pulmonary syndrome.
Find specialists →Symptoms (abdominal pain, fatigue) improve within 1-4 weeks of treatment. Eosinophilia resolves within 3-6 months. Hemoglobin rises 1-2 g/dL within 4-8 weeks when iron is co-administered. Iron stores replenish over 3-6 months. Growth and cognitive recovery in chronically infected children occurs over 6-24 months.
Activity tolerance is limited by anemia rather than by direct parasite effects. As hemoglobin normalizes over weeks, gradually resume normal physical activity. Children with severe anemia at diagnosis should avoid strenuous exercise until hemoglobin recovery is documented.
Choose a primary-care or pediatric service comfortable with deworming protocols. For returning travelers, refer to a travel and tropical medicine clinic capable of multiplex stool PCR, serology for Strongyloides and schistosomiasis, and management of mixed infections.
Medically reviewed by AIHealz Medical Editorial Board · May 13, 2026
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