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Hookworm
Primary Distribution: Most tropical and subtropical areas of the world.
Agent and Vector: Hookworms are intestinal parasites (nematodes, including Ancylostoma duodenale, Unicinaria stenocephala, and Necator americanus) of humans, dogs, and cats. Hookworm larvae are transmitted from soil through the skin.
Incubation: 2-8 weeks or longer.
Clinical Findings and Treatment
Signs and Symptoms: Most people (with small loads) are asymptomatic. Entry points are sometimes pruritic with a rash that may become secondarily infected. Higher loads result in anorexia or increased appetite, abdominal discomfort, weight loss, nausea and vomiting, diarrhea and/or constipation, and anemia. Respiratory symptoms occur in a few patients when larvae are in the lungs as part of the natural life cycle.
Complications: (Primarily in infants and children): severe anemia, protein deficiency, and developmental delays.
Laboratory Findings: Anemia, eosinophilia (in acute pulmonary stage), occult blood in stool.
Diagnosis: Iron deficiency anemia and living in an endemic area establishes suspicion. Direct fecal smears may require a concentration method to identify eggs.
Differential Diagnosis: Other causes of anemia
Treatment: Mebendazole 100 mg bid x 3 days or albendazole 400 mg in one daily dose x 2-3 days or pyrantel pamoate 10 mg/kg (maximum 1 gram) in a single dose. None of these medications are safe in pregnancy and neither mebendazole nor albendazole should be given to children under 1 year of age. The anemia should be treated with ferrous sulfate.
References
Centers for Disease Control and Prevention (1999). Hookworm infection. Online: http://www.cdc.gov/.
Goldsmith, R.S. (1999). Infectious diseases: Protozoal and helminthic. In L.M. Tierney, S.J. McPhee, & M.A. Papadakis (Eds.), Current Medical Diagnosis & Treatment (14th ed.) (pp.1353-1417). Stamford Connecticut: Appleton & Lange.