Cause of Cutaneous Larva Migrans
Cutaneous larva migrans is caused by penetration of human skin by third-stage filariform larvae of dog and cat hookworms, most commonly Ancylostoma braziliense and Ancylostoma caninum. 1, 2
Causative Organisms
- The primary causative agents are zoonotic hookworm species that normally infect dogs and cats, with Ancylostoma braziliense and Ancylostoma caninum being the most frequently implicated parasites 1, 2
- These larvae are present in the feces of infected dogs and cats and contaminate soil or sand 2
- The larvae cannot penetrate the basal membrane of human skin, so they remain confined to the epidermis and cannot complete their lifecycle, making humans an accidental dead-end host 1, 2
Transmission Mechanism
- Transmission occurs when naked skin comes into direct contact with contaminated soil or sand containing infective hookworm larvae 1
- The condition is most commonly acquired by walking barefoot or lying on contaminated beaches or soil 2
- Exposure can occur both outdoors and, exceptionally, indoors 1
- Rarely, larvae may be transmitted through fomites (contaminated objects) 1
Geographic Distribution and Epidemiology
- The condition has worldwide distribution with predominance in warmer, tropical and subtropical regions 3, 4
- It is endemic in many resource-poor communities in the developing world and is particularly common in the Caribbean and New World 1, 2
- In high-income countries, cutaneous larva migrans occurs sporadically or in small epidemics, with travelers accounting for the great majority of cases 1
Important Clinical Distinction
- This condition should be distinguished from human hookworm infection (Ancylostoma duodenale and Necator americanus), which causes minimal or no skin symptoms and proceeds to systemic infection 3, 5
- Human hookworm larvae penetrate skin and migrate internally, whereas zoonotic hookworm larvae causing cutaneous larva migrans remain trapped in the epidermis, creating the characteristic serpiginous rash 3, 1