Infectious Disease · Helminthic Infections
The facts most likely to be tested
Hookworm infection is transmitted via larval penetration of intact skin, typically through barefoot contact with contaminated soil.
The classic clinical presentation involves a pruritic, erythematous maculopapular rash at the site of entry, often referred to as ground itch.
Migration of larvae through the lungs can cause Loeffler syndrome, characterized by transient pulmonary infiltrates and peripheral eosinophilia.
Chronic infection leads to iron deficiency anemia due to the parasite's attachment to the small intestinal mucosa and subsequent blood loss.
Diagnosis is confirmed by the identification of hookworm eggs in a stool ova and parasite (O&P) exam.
The primary treatment for hookworm infection is an anthelmintic agent such as albendazole or mebendazole.
Patients with significant anemia require iron supplementation in addition to antiparasitic therapy to restore hemoglobin levels.
Vignette unlocked
A 28-year-old male presents to the clinic with a 3-month history of fatigue and lightheadedness. He recently returned from a volunteer trip in rural Southeast Asia where he frequently walked barefoot in agricultural fields. Physical examination reveals conjunctival pallor and a systolic flow murmur. Laboratory studies demonstrate a hemoglobin of 8.2 g/dL, microcytic hypochromic anemia, and peripheral eosinophilia. A stool O&P exam reveals the presence of characteristic hookworm eggs.
What is the most appropriate pharmacologic management for this patient?
Albendazole
The patient's presentation of iron deficiency anemia and eosinophilia following travel to an endemic area is classic for hookworm infection, which is treated with albendazole.
Full handout
High yield triage
Etiology / Epidemiology
Caused by Ancylostoma duodenale or Necator americanus via skin penetration in tropical/subtropical regions.
Clinical Manifestations
Presents with iron deficiency anemia and ground itch; look for eosinophilia on CBC.
Diagnosis
Stool ova and parasite (O&P) exam is the gold standard; look for eggs in stool.
Treatment
Albendazole is the first-line treatment; teratogenic in the first trimester.
Prognosis
Prognosis is excellent with treatment; anemia recovery requires iron supplementation.
Full handout
Epidemiology & Etiology
Infection occurs when filariform larvae in contaminated soil penetrate intact skin, typically in barefoot individuals. It is highly prevalent in regions with poor sanitation and warm, moist climates. Necator americanus is the most common species globally.
Pertinent Anatomy
Larvae migrate through the bloodstream to the lungs, ascend the bronchial tree, and are swallowed to reach the small intestine. Adult worms attach to the intestinal mucosa using teeth or cutting plates to feed on host blood.
Pathophysiology
Attachment to the intestinal wall causes chronic blood loss, leading to microcytic hypochromic anemia. The host immune response typically triggers a significant peripheral eosinophilia. Heavy worm burdens can lead to protein-losing enteropathy.
Clinical Manifestations
Initial skin penetration causes a pruritic, erythematous rash known as ground itch. Pulmonary migration may cause a transient Loeffler syndrome (cough, wheezing). Chronic infection manifests as iron deficiency anemia, fatigue, and pallor.
Diagnosis
The stool ova and parasite (O&P) exam is the gold standard for identifying characteristic eggs. A CBC will typically reveal eosinophilia and low hemoglobin. Stool samples must be fresh to ensure accurate identification of the hookworm eggs.
Treatment
Albendazole (400 mg once) or Mebendazole are the first-line agents. Albendazole is teratogenic and should be avoided in the first trimester of pregnancy. Iron supplementation is mandatory to correct the iron deficiency anemia.
Prognosis
Most patients recover fully with anthelmintic therapy. Severe anemia may require prolonged iron replacement therapy. Re-infection is common in endemic areas without improved sanitation.
Differential Diagnosis
Ascariasis: usually presents with larger worms and intestinal obstruction
Strongyloidiasis: characterized by autoinfection and hyperinfection syndrome
Trichuriasis: typically presents with rectal prolapse in heavy infections
Enterobiasis: presents with nocturnal perianal pruritus
Iron deficiency anemia (non-parasitic): lacks eosinophilia and travel history