Miguel Imperial MD FRCPC (biography, no disclosures)
What I did before
Cutaneous larva migrans (CLM) is a zoonotic worm infection that presents in travelers as an intensely pruritic, serpiginous skin eruption that is caused by the migration of these animal-origin (i.e. dog and cat) hookworm larva in the subcutaneous skin. Travelers to tropical and sub-tropical climates most often acquire this parasitic infection through direct contact with larvae-contaminated sand or soil. Although self-limited, the symptoms can cause considerable discomfort and distress.
The most frequent care gaps that I have noticed are (a) not correctly identifying the skin eruption as a treatable parasitic infection and (b) using the incorrect therapy, as access to the appropriate anti-helminthic drugs has been a challenge in Canada.
- Diagnosis
The travel history and the characteristic eruption are the two most important factors in correctly identifying this infection. Travel to a tropical or sub-tropical climate and direct skin exposure to hookworm larvae (e.g. laying directly on the sand without a mat, walking barefoot on the sand or being buried in the sand) is the usual history. Areas of the beach that are shaded (i.e. under trees) and away from the water are much more likely to be able to harbor viable and infective hookworm larvae.
As for the skin eruption, it may start as little as a day after exposure but occasionally presentation may be delayed by more than a month as some larvae can remain dormant in the skin for some time. The rash may start as itchy papules but then quickly, the characteristic serpiginous subcutaneous tracts appear as a local tissue reaction to the larvae migrating in the skin. Biopsy is not helpful for diagnosis, nor is there is ever any indication for trying to surgically excise migrating larvae.
- Treatment
In the past, I would consider treating patients for (1) the itch and skin inflammation, with either topical or systemic steroids and an antihistamine and (2) definitively with a topical antihelminthic: topical thiabendazole 15% in petroleum jelly, applied 2-3 times a day to the affected area for 1-2 weeks. Unfortunately, only select compounding pharmacies had timely access to thiabendazole. Furthermore, while topical therapy was usually effective, it was a challenge to use when the infection was severe and widespread. One of my patients who returned from Jamaica where his nieces and nephews had buried him up to the neck in contaminated sand, had lesions virtually over his entire body.
Unfortunately, the two other antihelminthic drugs that could be used for systemic treatment (albendazole and ivermectin) were not available for human use in Canada. They required Special Access application through Health Canada, a hurdle that often resulted in a treatment delay while authorization was sought.
Other patients I had seen in referral had already been given a course of the antihelminthic mebendazole (trade name: Vermox) which was unlikely to resolve their infection. Mebendazole is an oral drug that is effective for intestinal roundworms and hookworm infection, but it has poor systemic absorption, making it relatively ineffective for systemic and tissue stages of worm infections.
What changed my practice
As of September 2018, Health Canada finally approved the human use of Ivermectin, meaning it can be accessed through any community pharmacy.
Ivermectin is an effective oral treatment for CLM with few side effects.
What I do now
Once I diagnose a patient with CLM based on a compatible travel history and characteristic serpiginous rash, I continue to treat the itch and inflammatory symptoms symptomatically if indicated, but I am able to much more readily offer systemic therapy with ivermectin since it no longer requires a Health Canada Special Access application. Ivermectin is given as a weight based dose of 200 mcg/kg po once daily for 1-2 days. For an average 70kg person, that works out to ivermectin 15mg once a day for 1-2 days. (note that it comes in 3mg tablets)
For localized infections (i.e. to one foot), I still offer the option of topical therapy with thiabendazole 15% in petroleum jelly tid x 7-14 days.
Images from Centers for Disease Control and Prevention www.cdc.gov/parasites:
- https://wwwnc.cdc.gov/eid/images/09-0261-F1.jpg
- https://www.cdc.gov/parasites/images/zoonotichookworm/cutaneous-larva-migrans-clm-patient_1.jpg
- https://www.cdc.gov/parasites/images/zoonotichookworm/clm_1.jpg
References
- Blackwell V, Vega-Lopez F. Cutaneous larva migrans: clinical features and management of 44 cases presenting in the returning traveller. Br J Dermatol 2001; 145:434. (Request from CPSBC or with UBC http://tinyurl.com/yy23d7s3)
- Feldmeier H, Schuster A. Mini review: Hookworm-related cutaneous larva migrans. Eur J Clin Microbiol Infect Dis 2012; 31:915. (View with CPSBC or with UBC http://tinyurl.com/y3ktdzmg)
- Kincaid L, Klowak M, Klowak S, Boggild AK. Management of imported cutaneous larva migrans: A case series and mini-review. Travel Med Infect Dis. 2015 Sep-Oct;13(5):382-7 (View with CPSBC or with UBC http://tinyurl.com/y5outv7r)
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Nice approach and fact about importance of history of travel.
Good overview of available medications and the best treatment options.
Thanks for the information on risky beach sand exposures, and on treatments.
Excellent update in a nutshell
I have seen this infection in my office on a number of occasions and am glad to hear that Ivermectin is now available in Canada. Excellent update on risk factors, diagnosis and management for Canadian primary care physicians given the frequency of vacation travel of our population to highly endemic areas!
Very good.
I have a patient who travels quite a bit to warmer climes, has chronic respiratory issues (and is on prednisone quite often), along. with chronic anemia -remote Roux en y – family history of death due to colorectal cancer at age 57. This rash is new and she described it as starting with little blisters on her lower back. They have gone.The current, large serpentine rash is on her upper back. No recent travel but the rash is alarming. I am looking into DDX shingles. I actually did a house call as staff said she wasn’t feeling well enough to come to her appointment. I am her psychiatrist in a shared care team. She expressed she felt dismissed by her GP. Seeing her labs before the house call I was very surprised. Her Hb is 87 g/L which is low even for her. Pathologist remarked on slight microcytosis.
She is of course concerned about the family hx cancer; B12 normal without supplement. ESR normal. No iron infusion suggested and she has never had any.
She has a small, older terrier type dog that looked well. She hasn’t had him dewormed for years.
Considering the chronically low Hb that seems resistant, chronic cough, and this rather alarming rash I wonder if it is hookworm. I know it can cause severe anemia in dogs and rarely goes to the lungs.
But, alas, I am not a “real Dr” being a psychiatrist. So for my part am lending an ear, referring to an Internist who specializes in bariatric medicine, and running this idea to her GP, who reportedly ran from the room when he saw the rash and later told her he is planning a punch biopsy.
The rash was impressive. I wonder if the prednisone she is on is suppressing any itching. I would have expected it in either migrans or shingles.