Schistosomatid dermatitis (cercariosis)

Schistosomatid dermatitis (cercariosis, itch bathers, water itch, cervical dermatitis) is a parasitic disease characterized by skin changes caused by the larvae (cercariae) of some species of trematodes.

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Epidemiology of schistosomatid dermatitis (cercariosis)

Penetration of cercariae through the skin of a person is possible only in those reservoirs in which the intermediate hosts of such schistosomes are located - pulmonary mollusks. Most cercariae die in the skin, causing inflammatory reactions. Most often schistosomatid dermatitis is caused by cercariae Tr. Ocellata and Tr. Stagnicolae.

Eggs of trichobilgations enter the water with feces of hosts, from them hatch miracidia, penetrating the mollusks of the genera Lymnaea, Planorbis and others, where parthenogenetic reproduction and development of larvae occur to the stage of cercaria. Cercariae emerge from mollusks and are introduced through the skin to the body of ducks and other waterfowl, where their development continues. After 2 weeks in the circulatory system of the host parasites reach sexual maturity.

[8], [9], [10], [11], [12]

What causes schistosomatid dermatitis (cercariosis)?

The causative agents of schistosomatid dermatitis are larvae (cercariae) of schistosomes of the family Schistosomatidae, parasitizing in the adult state in the circulatory system of waterfowl (ducks, gulls, swans, etc.). Man is not a specific host for them. Sometimes dermatitis can be caused by cercariae of schistosomatids of mammals (rodents, etc.). Currently, there are more than 20 species of schistosomes, cercariae of which are able to penetrate the human skin.

The pathogenesis of schistosomatid dermatitis (cercariosis)

The cause of human infection is the ability of cercariae of schistosomatid to actively penetrate the skin. Cercariae cause mechanical (often multiple) lesions of the skin and have toxic and sensitizing effects on the human body, contribute to the introduction of secondary infection. Especially severe cercariosis occurs in children.

In places where cercariae are introduced into the human skin, edema develops with the lysis of epidermal cells. As the cercariae migrate in the corium, infiltrates from leukocytes and lymphocytes appear. As a result of the developed immunological reaction, schistosomatids in the human skin are killed, and their further development ceases.

Symptoms of schistosomatid dermatitis (cercariosis)

In 10-15 minutes after penetration into the skin of cercariae, typical symptoms of schistosomatid dermatitis (cercariosis) appear: skin itching, and an hour after bathing, a spotty rash appears on the skin, disappearing after 6-10 hours. In highly sensitive individuals, local and general urticaria, allergic edema and severe itching of the skin may occur.

With repeated infection, the dermatitis phenomenon is more pronounced: the skin produces erythema and red papules, accompanied by severe itching. In the center of some papules appear hemorrhages. Papules appear on the 2-12th day after infection and persist up to 2 weeks. Occasionally there is swelling of the skin and blisters. Schistosomatid dermatitis (cercariosis) results in spontaneous recovery. Pigmentation is retained in place of the papules for several weeks.

Differential diagnosis of schistosomatid dermatitis (cercariosis)

Diagnosis of schistosomatid dermatitis (cercariosis) is based on the appearance of characteristic skin changes in contact with water in water bodies where mollusks and ducks live (bathing, fishing, irrigation works, etc.). Cercariosis differentiates with reactions to insect bites and other dermatitis.

Schistosomatid dermatitis (cercariosis) has a favorable prognosis.

[13], [14], [15], [16], [17]

Treatment of schistosomatid dermatitis (cercariosis)

Symptomatic treatment of schistosomatid dermatitis (cercariosis) is performed by prescribing desensitizing (dimedrol 0.05 g 2-3 times a day) and local anesthetic (5-20% oil solution of benzocaine or anestezin). Zinc ointment and starch trays are also used. In severe cases, the use of glucocorticoids is indicated. With the development of schistosomiasis treatment is carried out by anthelmintics.

How to prevent schistosomatid dermatitis (cercariosis)?

For personal prophylaxis of cercariosis in contact with water in water bodies (bathing, washing clothes, playing in water, fishing, etc.), it is necessary:

• To avoid shallow water areas covered by water vegetation (or their zones) where ducks live (coastal zones that are deprived of aquatic vegetation are more safe);
• If you need a long stay in water, wear protective clothing and shoes (boots, trousers, shirt) that protect against attacks of cercariae schistosomatid;
• after contact with water in the "suspicious" area of the reservoir, wipe the skin thoroughly with a hard towel or a dry cloth and
• quickly replace wet clothes.

Public prevention of cercariosis includes:

• equipment of internal urban water bodies where there is a risk of infection of people with cercariae, signs prohibiting bathing and playing in the water;
• regulation (reduction) of the number of mallards in urban water bodies used for recreational purposes;
• regular cleaning of water bodies (or the most visited areas of water bodies) from aquatic vegetation.