- Pathogen
- Human hookworms: Ancylostoma duodenale and Necator americanus
- Zoonotic hookworms, i.e., cat and dog hookworms (Ancylostoma braziliense and Ancylostoma caninum) can also infect humans.
- Hookworms are nematodes.
- Mode of transmission: percutaneous penetration of larvae (primarily via the feet, e.g., while walking on a beach)
- Life cycle
- Human hookworm: Soil is contaminated with human feces containing hookworm eggs → Eggs hatch and release larvae → Larvae penetrate skin (usually the feet) → Larvae migrate to lungs via blood and lymphatic vessels → Larvae migrate via bronchi and trachea to the larynx → Larvae are expectorated and swallowed back into the intestine → Larvae mature into adult worms that colonize the intestinal tract → Female hookworms lay eggs in the intestine → Eggs are eliminated with the feces.
- Zoonotic hookworms are usually unable to break through the basement membrane after entering the human epidermis (humans are accidental intermediate hosts) → Migration through the epidermis for several weeks.
- Clinical features
- Cutaneous symptoms
- At entry site: pruritus, erythema, maculopapular rash
- Cutaneous larva migrans (CLM): serpiginous marks (cutaneous lesion with a progressive, creeping, snake-like border) representing larval tracks
- In zoonotic hookworm infections, only cutaneous symptoms are present.
- Respiratory tract: dry cough, wheezing, Loeffler syndrome
- Intestine: abdominal pain, weight loss, nausea, vomiting, diarrhea
- Microcytic anemia (hookworms ingest blood from the intestinal wall)