What is the cause of swimmer's rash, also known as (Cercarial dermatitis)?

From the Guidelines

Swimmer's rash, also known as cercarial dermatitis, should be treated with topical corticosteroids to alleviate symptoms, as it is a self-limiting condition with no serious sequelae, resolving spontaneously over days to weeks 1. To manage swimmer's rash, the following steps can be taken:

• Apply cool compresses or calamine lotion to affected areas for relief
• Use over-the-counter hydrocortisone cream (1%) applied to affected areas 2-3 times daily
• Take an antihistamine like diphenhydramine (Benadryl) 25-50mg every 6 hours or non-sedating options like cetirizine (Zyrtec) 10mg daily to reduce itching The condition is caused by a localized subcutaneous infection by species of schistosome, usually infecting birds, and is characterized by an itchy maculopapular rash, with an incubation period of hours and worldwide distribution, often occurring in outbreaks 1. Prevention measures include:
• Thoroughly drying off with a towel immediately after swimming, especially in lakes or ponds
• Showering with soap as soon as possible
• Avoiding swimming in areas with posted warnings about swimmer's itch, particularly shallow, warmer water near shorelines where parasites are more common It is essential to note that the parasites causing swimmer's rash cannot complete their life cycle in humans, so the condition is not contagious between people.

From the Research

Swimmer's Rash

• Swimmer's rash, also known as swimmer's itch, is a skin condition that occurs after exposure to certain substances in the water, such as allergens or irritants.
• The exact cause of swimmer's rash is not specified in the provided studies, but it can be related to contact dermatitis, which is a common inflammatory skin condition characterized by erythematous and pruritic skin lesions that occur after contact with a foreign substance 2, 3.
• Contact dermatitis can be caused by various substances, including poison ivy, nickel, and fragrances, and can be classified into two forms: irritant and allergic contact dermatitis 2.
• Treatment of contact dermatitis typically involves avoiding the suspected irritants or allergens, restoring the skin barrier, and reducing skin inflammation through multiple treatments, such as emollients, topical corticosteroids, and antihistamines, as well as systemic corticosteroids and immunosuppressants 3.

Treatment Options

• Topical corticosteroids are an essential tool for treating inflammatory skin conditions, including contact dermatitis, and are classified by strength and the risk of adverse effects 4.
• The choice of topical corticosteroid depends on the severity of the condition, the location of the affected area, and the patient's age and medical history 4, 5.
• Systemic corticosteroids may be required for extensive or severe cases of contact dermatitis, and oral prednisone should be tapered over two to three weeks to avoid rebound dermatitis 2.

Prevention and Management

• Prevention of contact dermatitis involves avoiding exposure to known allergens or irritants, and using protective measures such as gloves or clothing to minimize skin contact 3.
• Early and appropriate treatment of contact dermatitis is important to prevent further deterioration and persistence of the skin condition 3.
• Patch testing and other diagnostic tests can be used to identify the causative allergens and guide treatment decisions 2, 3.