After percutaneous invasion, the larvae migrate along the upper dermis, causing inflammatory erythematous lesions to form along their tortuous tracks, which can advance several centimeters in a day. First stage larvae hatch from embrionated eggs passed in animal feces, and mature to third-stage infective larvae in the soil. This usually occurs after contact with soil, generally sandy and damp beaches of tropical and subtropical countries, contaminated by feces of infected dogs and cats. Humans are, however, also the definite host for these nematodes and may be afflicted with much more diverse clinical manifestations.( 30) Finally Lagochilascaris minor may also cause cutaneous larva migrans but the larvae can develop into adult worms in humans causing severe visceral, ocular, or central nervous system disease.įor hookworms of domestic animals man is an occasional host and is infected accidentally.
Furthermore, the larvae of Ancylostoma duodenale or Strongyloides stercoralis (the latter causing the disease known as larva currens) may also penetrate the skin and cause a syndrome similar to cutaneous larva migrans. This disease, in which the patients seem to have acquired the infection by eating raw seafood or squid is the most common cause of creeping eruption in Japan.( 32). Some authors also consider creeping disease due to larva of Spiruroidea nematodes part of this syndrome. Even the larvae of some of the myaisis-inducing flies ( Gasterophilus and Hypoderma sp.) have been associated with the condition. Other geographically restricted nematodes, may occasionally manifest as larva migrans syndromes, such as Gnathostoma, Angiostrongylus and Anisaka. Other nematode parasites of domestic and wild animals have been implicated in causing similar lesions, such as Uncinaria stenocephala the Northern hookworm of dogs, Bunostomum phlebotomum, the cattle hookworm, Gnathostoma spinigerum, a nematode endemic in Asia, Dirofilaria sp, Baylisascaris procyonis, a parasite of raccoons, and Strongyloides westeri, an equine parasite. Ancylostoma caninum and Ancylostoma braziliense.
Cutaneous larva migrans is most often caused by infective-stage larvae of animal hookworms, usually the dog and cat hookworms. This aberrant migration may be prolonged, inciting a local or systemic eosinophilic response that is responsible for many of the signs and symptoms of these infections. The developmentally arrested nematode larvae do not mature to adult worms within the human body, but rather migrate through superficial tissues. Larva migrans syndromes are caused by the accidental infection of humans by infective larvae of helminthic species that are normally parasitic for other carnivorous mammals. Cutaneous larva migransis a widespread and well-recognized disease in the tropics and is considered the most common dermatological problem affecting westerners after travel to tropical countries ( 5, 11, 17, 19, 28, 32, 36). In vitro experiments demonstrated that ivermectin: (1) was highly detrimental to actively motile adult worms in concentrations greater than 5.60 micrograms/ml (2) was detrimental to eggs inside the uterine tissue of female worms in dosages at or greater than 10 micrograms/kg body weight and (3) killed infected larvae in concentrations as low as 0.0025 micrograms/ml.Clinically, cutaneous larva migrans (CLM) or creeping eruption, is a raised, erythematous, linear or serpiginous skin eruption, which is often accompanied by intense pruritus. No untoward reaction to ivermectin or significant pathological change was noted in the experimental animals. Albendazole, a known anti-hookworm agent, even in a dose of 400 mg, eliminated only 21-65% of the worms harbored by the infected animals.
In contrast, an average of 178 worms per dog was recovered at necropsy from the vehicle-treated control and the untreated animals. Each of these dosages was effective in clearing the infection completely, so that numerous worms were passed in the feces on days 1-3, but no worm was recovered from the intestinal tract at necropsy on day 4 after treatment. Single oral doses of ivermectin were given to dogs with moderate or heavy infections of Ancylostoma caninum (egg counts ranging from 7,100 to 41,700 eggs/g feces) at 100, 50, 30, or 10 micrograms/kg body weight.