HrCLM is one of the most frequent cutaneous parasitic infestations seen among people living in tropical and subtropical areas, including Southeastern Florida [2,3,8]. This dermatosis was described for the first time in 1874 as “creeping eruption” [2,3]. HrCLM is caused by the inadvertent penetration and migration of animal hookworm larvae through the epidermis. The most common parasite species include Ancylostoma braziliense (hookworm of wild cats, and domestic cats and dogs) and Ancylostoma caninum (dog hookworm) [9]. The adult worms thrive in the intestines of their definitive host (cats and dogs) and release their eggs into the environment via defecation. These eggs mature in the soil, protected from desiccation and intense temperatures, from first to third stage larvae (filariform larvae) capable of infecting other animal hosts through skin penetration (Figure 3) [4]. Warm, humid and shadyfields, sand piles or seashores are especially favored areas, therefore making farmers, gardeners or beach visitors prone to acquiring the infestation occupationally or accidentally [10]. In the case of our patient, there was a history of homelessness and residence in Miami prior to presentation. The time of incubation has not been specified, but an incubation time of several days to a month is commonly seen [7,11,12]. The parasites infect humans as incidental hosts via direct contact with infested areas by walking and standing on the sand. Contrary to their presence in the definite host, the filariform larvae in humans are unable to mature, and instead migrate aimlessly, confined to the epidermis and sometimes the upper dermis [3]. These larvae migrate at the rate of 1 to 2 cm per day with a half-life between 2 to 8 weeks [2-4]. Jackson et al. found that the length of the eruption track was associated with the duration of the infestation, with a rate of 2.7 mm increase in length per day therefore time of exposure can be calculated [13]. In our patient with multiple tracks and entry points, the longest track was no more than 50 mm, indicating an incubation period less than 20 days.

After the filariform larvae penetrates and migrates within the epidermis by enzymatic digestion of keratin, a local inflammatory reaction develops, distinguished initially by a pruritic papule that develops into a pruritic serpiginous erythematous track 1 to 6 days after inoculation [2,4,10]. The tracks left by the larvae during migration desiccate and then become filled with a scab [2,3,14]. Vesicles, papules and crusts frequently appear along the track. Impetigo may result following secondary bacterial infection from scratching due to intense pruritus [10]. The most commonly affected regions are the dorsum of the feet; legs and the buttocks less commonly. Lesions on the anterior abdominal wall and penile shaft may occur rarely; but any part of thebody in contact with the larvae can be involved (Table 1) [2,10,15]. Most of previously reported cases showed a single-entry point of larva infestation and like seen in our case, multiple entries in different anatomic sites are less common (Table 1). This unusual presentation might lead to an inappropriate and/or delayed intervention [16]. Cough, wheezing, and chest pain may occur rarely, and pulmonary eosinophilia (Loeffler’s pneumonia) occurs sometimes in patients with allergic diseases [10].

Differential diagnosis includes other creeping eruptions (i.e. larva currens, gnathostomiasis), subcutaneous swelling lesions (i.e. scabies and myasis), allergic contact dermatitis, and tinea pedis [20,21]. In larva currens, Strongyloides stercoralis also causes a serpiginous track; however, the larval path migrates faster at a rate of 5-10 cm/h compared with the 1-2 cm/day from the cat or dog hookworm. The serpiginous track is an urticarial wheal bounded by an itchy flare that lasts a couple of hours [16]. Contrary to HrCLM, contact to the larvae of Ancylostoma duodenale or Necator americanus leads to a pruritic, papulo-vesicular rash called “ground itch” [22]. Gnathostomiasis is an infection that travelers may get in Southeastern Asian countries and triggered by a nematode acquired by the human consumption of inappropriately cooked amphibians or shellfish. The migratory and serpiginous track is longer and more swelling is associated than that of dog and cat hookworm. Furthermore, gnathostomiasis histology is consistent with eosinophilic panniculitis (deep dermis) [16,20].

Although HrCLM is self-limited, treatment with anti-helminthic agents is generally recommended due to possible complications (e.g. secondary bacterial infection and allergic reactions) in conjunction with the severe pruritus (Table 1) [2,17,21]. Albendazole and ivermectin are acceptable as first-line treatments; however, topical treatment is another alternative. Administration of 400 units/day oral dose of albendazole for 3 to 7 days results in cure rates of 80 to 100% [8]. Some potential side effects include headache and increased liver enzymes in up to 15% of the patients. Furthermore, administration of ivermectin consists of 200 mcg/kg once daily for one or two days with a cure rate of 94 to 100% in a single dose and pruritus, tachycardia, eosinophilia, and increased liver enzymes as side effects [23,24]. Topical application of thiabendazole 10 to 15% three times daily for 15 days can be used for localized presentations [8,17,21]. Use of liquid nitrogen (cryotherapy) at the leading edge of the skin track can be taken into consideration only in small, single lesions of HrCLM; however, is painful and usually ineffective since the larva is generally situated beyond the end of the track [2,10,21], therefore is not recommended. Since our patient had multiple uncomplicated lesions, systemic treatment was indicated, with early resolution of the lesions after treatment. However, the multiple infestation sites seenin our patient should not suggest an increase in the treatment dosage since this extensive presentation seems to respond well to standard therapy, as seen in a previous case report [16].

Some suggestions for disease prevention include avoiding contact of bare skin with contaminated soil by coating the ground with impermeable material while sitting or lying, the use of footwear, preventing walking on bare feet and forbidding dogs and cats at beach areas [10].

HrCLM is a fairly prevalent cutaneous parasitic infestation affecting tropical and subtropical areas including South Florida. The infestation is acquired through direct inoculation with Ancylostoma braziliense or Ancylostoma caninum larvae in contaminated soil or sand, and is thus frequently seen in the homeless population. The diagnosis of HrCLM is often clinical, though varying presentations are possible, such as its presence of multiple larva entries seen in our case. HrCLM is self-limited in immunocompetent people, though oral and topical anti-helminthic agents such as albendazole and ivermectin are used to shorten the course of disease and prevent subsequent complications.