Cutaneous larva migrans is a group of infectious skin diseases associated with the defeat of helminth larvae. The main symptom is dermatitis in the form of filamentous lines formed when the pathogen moves in the upper layers of the dermis. The rash is accompanied by severe itching, most often the lower extremities are affected. Typical symptoms make it possible to make a diagnosis based on the clinical picture and anamnesis, it is possible to detect larvae in the skin during biopsy. Treatment is etiotropic (anthelmintic drugs) and symptomatic; local application of chloroethyl is allowed, in rare cases surgical intervention is indicated.
B76.9 Hookworm disease, unspecified
Cutaneous larva migrans (larva migrans, creeping disease) is a collective name for a group of skin larval lesions. The first written mention of the disease dates back to 1874, the clinical description of nosology was given by White and Dove in 1929. Pathology is common in tropical countries, on the territory of the former USSR, USA, Europe. There is a direct dependence of the incidence on the season – rains contribute to the dispersion of eggs and larvae of the parasite. The frequency of atypical localization of the lesion (trunk, buttocks, head) also depends on seasonal changes due to the use or non-use of shoes and closed clothing.
The most common pathogens are hookworm larvae Ancylostoma braziliense, A. ceylanicum, A. caninum. The path of infection is contact (through the skin). For helminths, a person is a biological dead end – parasites, with rare exceptions, cannot pass through the basement membrane of the epidermis, as a result of which the larvae die in the skin before reaching puberty. Chaotic migration inside the upper layers of the skin leads to the appearance of convoluted (serpiginous), less often linear strokes.
The sources of infection are dogs and cats, in the intestines of which mature individuals live. It is believed that hookworms affect up to 50% of stray dogs. With feces, parasite eggs are released into the environment, where larval forms develop in conditions of high humidity, shade and heat. When being on the sand without shoes and lying for a long time, the larvae actively penetrate the skin. Risk factors – male sex, young age, living in unsatisfactory social and hygienic conditions, on the territory with contamination by animal feces.
Larvae enter the human body through accidental contact through the holes of hair follicles, microcracks or through intact skin, which is destroyed by protease produced by parasites. The dermal restriction of advancement is due to the small amount or absence of collagenase produced by the larva, which is necessary for the cleavage of the basement membrane. Usually the pathogen is located in the granular epidermal layer, extremely rarely penetrates into the underlying integuments, but quickly returns back.
The location of the stroke is not related to the localization of the larva, since the movement of the latter is chaotic and disorderly. It is possible to have both single and multiple passages filled with serous discharge. Sometimes urticary and erythematous rashes are detected. Larvae are found directly in the thickness of the epidermis in the suprabasal layers, as well as inflammatory phenomena of allergic genesis: necrotic keratinocytes, spongiosis, intraepidermal vesicles, a large number of neutrophils and eosinophils.
The incubation period is 1-5 days, can be shortened to several hours or lengthened to a month or more. At the site of the introduction of the larva, there is a strong itching, soreness, burning, a red bump appears. About 40% of cases of invasion occur on the skin of the lower extremities, 20% – on the buttocks, genitals, 15% – on the abdomen. As the larva progresses, towering sinuous thread-like lines of reddish-brown color appear on the skin, emanating from the primary tubercle.
The parasite moves relatively slowly, up to 1-3 cm per day, its movement may not be felt by the patient, rare manifestations are considered edema of the invasion area, pustules around the hair follicles. Symptoms persist from 4 weeks to 6 months, can regress independently. About 50% of patients report the appearance of a dry nasal cough with scanty sputum. Body temperature usually remains normal, a sharp increase may indicate the addition of a secondary bacterial infection.
The most frequent complications of cutaneous larva migrans are purulent inflammatory processes in the skin associated with the addition of pyogenic flora: impetigo, abscesses, folliculitis. Complications are often observed against the background of taking etiotropic drugs, their effects on the gastrointestinal tract, central nervous system and other organs. Less common massive invasion of the parasite leads to swelling and lymphostasis of the extremities, cases of Leffler syndrome, eosinophilic enteritis, erythema multiforme exudative and bullous skin lesions have been described. In the case of migration of larvae through the bloodstream and getting into the lung tissue, bronchitis, pneumonia, pleurisy are formed.
The diagnosis of a cutaneous larva migrans is confirmed by an infectious disease specialist, an examination by a dermatovenerologist and other doctors is often required. A thorough collection of epidemiological anamnesis is required with the clarification of trips to natural areas endemic for this disease. Diagnostic methods necessary for the verification of larval lesions include the following techniques:
- Physical examination. On objective examination, characteristic serpiginous filamentous convoluted passages are found on the skin of the feet, buttocks, abdomen, and less often other parts of the body, raised above the skin, brownish-brown in hue up to 5 cm long and 3 mm wide. There are combs due to severe itching. Internal organs and systems are usually normal.
- Laboratory tests. Characteristic changes in the general clinical blood test are leukocytosis, eosinophilia (up to 50%) and a slight acceleration of ESR. Biochemical parameters are within normal limits, except for hypergammaglobulinemia. An immunogram can reveal an increase in the level of Ig E. In the rarest cases of allergic lung damage, it is possible to detect up to 90% of eosinophils in sputum.
- Identification of infectious agents. The proof of invasion is the visualization of larvae in skin biopsies. For the purpose of differential diagnosis, skin and perianal scrapings are examined, ELISA with borreliosis antigens is performed, fecal microscopy is performed to identify eggs and live parasites, in some cases, the passages are opened with a scalpel treated with vaseline to detect the pathogen.
- Instrumental techniques. Lung x-ray is necessary to exclude damage to the lower respiratory tract. Ultrasound examination of the abdominal organs is prescribed to exclude parasitic invasions with visceral manifestations, according to indications, ultrasound of soft tissues, lymph nodes in the area of skin symptoms is performed.
Differential diagnosis is carried out with migrating miasis, for which rapid (up to 30 cm per day) advancement inside the skin of insect larvae is typical, ring-shaped erythema with ixodic tick-borne borreliosis in the form of spots with straight contours not raised above the surface. With fungal skin infections, plaques and peeling are noted. The symptoms of the cutaneous larva migrans are also similar to scabies, characterized by straight linear passages of whitish-gray color, and contact dermatitis, which occurs after skin contact with an allergen, accompanied by the appearance of vesicles and hyperemia in the absence of serpiginous passages.
Treatment is usually carried out on an outpatient basis. Special dietary recommendations have not been developed, a common table and an adequate water regime are assigned. Etiotropic therapy of cutaneous larva migrans involves oral administration of albendazole, ivermectin and thiabendazole, the effectiveness is 75-89%. Local application of cream or suspension with albendazole is possible, the effect is achieved in 96-98% of cases.
To relieve itching, the use of antihistamines and desensitizing agents is recommended, and antibiotics are indicated in the event of purulent complications. Some effectiveness of local cryotherapy with liquid nitrogen is described, however, if it is used incorrectly, long-term non-healing ulcers can form. There is a high probability of the absence of a face in the nitrogen-treated course and the survival of the helminth, since the parasite is able to maintain viability at -21 ° C for more than 5 minutes.
Prognosis and prevention
The prognosis is favorable, no deaths were recorded. With an uncomplicated course of the disease, symptoms tend to disappear independently within about 3-5 weeks. Every year, up to 22-58% of cases of cutaneous larva migrans are misinterpreted by medical professionals, as a result of which complications arise, adequate treatment is not prescribed. The cause of diagnostic errors is an implicit or blurred symptomatology with a predominance of itching in the absence of other complaints.
Specific prophylactic agents (vaccines) have not been developed. Non-specific measures to prevent infection are personal hygiene, refusal to bathe and swallow water in random reservoirs, walking on sand and soil in rubberized closed shoes, the use of gloves and closed-type clothing when working with soil and plants. It is necessary to carry out planned deworming of pets, the exclusion of dog walking on children’s playgrounds.