Cutaneous Larva Currens

A Roundworm Infection

Magnified Strongyloides stercoralis
Strongyloides stercoralis in human stool. Cultura Science/Michael J. Klein, M.D. / Getty Images

What is cutaneous larva currens?

Cutaneous larva currens is a disease caused by Strongyloides stercoralis, and thus a type of strongyloidiasis.  Strongyloides stercoralis is a roundworm parasitic to humans. S. stercoralis is endemic to places such as Southeast Asia, Africa, and Central America and is most often encountered in fecally-contaminated soil or water and in tropical and subtropical regions.

This skin disease is characterized by itch of the skin as well as the appearance of snake-like, mottled hives around the waist and buttocks. It should be noted that cutaneous larva currens is not the same as the more well-versed skin condition cutaneous larva migrans (CLM).

How does cutaneous larva currens develop?

Each larva of this parasite enters the human by penetrating the skin, usually upon the host’s contact with contaminated soil. The larva then enters the bloodstream which takes it to the lungs and, ultimately, the pharynx, where it is then swallowed into the gut. Upon reaching maturation in the small intestine, female members of the species will lay eggs into the intestine’s mucosal layer. These eggs hatch into larvae that re-perpetuate the cycle within the host’s body.

As the number of S. stercoralis increases in the host, they can spread to various other body parts. If these roundworms migrate to the skin, this can result in the dermatological condition known as cutaneous larva currens.

What are signs of cutaneous larva ​currens in the skin?

Signs of cutaneous larva currans generally begin within two weeks following larvae entry. The raised “track lines” that are characteristic of the disease highlight the trail of the larvae as they migrate through the top layer of the skin. The rate of migration may vary from 5 to 15 cm per hour.

As the disease progresses, red, inflamed skin marks can appear, as well as raised hives and occasional  blisters. Fever is also sometimes present. Hive-like marks may last for several hours. In severe infection, bruising may be present around the umbilicus (belly button).

How can I prevent cutaneous larva ​currens?

Cutaneous larva currens can be prevented by avoiding contact with the Strongyloides larvae. One should avoid moist soil contaminated with animal feces, especially in a tropical or endemic country. Since beaches are common culprits for cutaneous larva currens infection, footwear should be worn on the sand, and a towel should be used if one is sitting on the ground.

How is cutaneous larva ​currens diagnosed?

Diagnosis is usually made by the dermatologist upon physical examination of the affected areas. If necessary, microscopy can also be used to identify the larva.

How is cutaneous larva currens treated?

The most effective treatments for cutaneous larva currens are antiparasitic drugs, such as ivermectin, albendazole, and thiabendazole.

Ivermectin (drug names: Heartgard, Sklice, and Stromectol, among others) is what is known as a broad-spectrum antiparasitic agent and is perhaps the most popular choice when it comes to cutaneous larva currens. It works by activating nonvertebrate-specific chloride channels and interferes with the parasites’ nervous system, effectively killing adult S. stercoralis. However, multiple doses may be needed in order to completely eradicate the roundworms as it does not target S. stercoralis in its larval form.

Albendazole (drug name: Albenza) kills S. stercoralis by causing the destruction of cells in the parasite’s intestines. Thiabendazole works by restricting specific enzymes within the worm. Notably, however, thiabendazole is known to have a higher level of toxicity than other antiparasitic drugs. This may be especially dangerous for patients with hepatitis or GI intolerance. Complete eradication of the parasite may take up to several years, as there is a tendency for strongyloidiasis to become chronic.

References:

1) Smith, James D., Detlef K. Goette, and Richard B. Odom. "Larva Currens: Cutaneous Stronglyloidiasis." Archives of dermatology 112, no. 8 (1976): 1161-1163. 

2) Stone, Orville J., Gordon B. Newell, and J. Fred Mullins. "Cutaneous strongyloidiasis: larva currens." Archives of dermatology 106, no. 5 (1972): 734-736. 

3) Jelinek, T., H. Maiwald, H. D. Nothdurft, and T. Löscher. "Cutaneous larva migrans in travelers: synopsis of histories, symptoms, and treatment of 98 patients." Clinical infectious diseases 19, no. 6 (1994): 1062-1066. 

4) Blackwell, V., and F. Vega‐Lopez. "Cutaneous larva migrans: clinical features and management of 44 cases presenting in the returning traveller." British Journal of Dermatology 145, no. 3 (2001): 434-437. 

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