Some people develop red, itchy blisters after swimming. This is a parasitic disease called cercariasis, or "swimmer's itch." The causative agent of this disease is microscopic larvae of waterfowl helminths, which parasitize the bodies of intermediate hosts – freshwater pond snails. The larvae move freely in the water and thus enter the body of the definitive hosts – ducks and gulls, or they can enter an accidental host – a person who has been "lingering" in the water. They quickly die in the human body but manage to cause an allergic reaction.
Typically, 10-15 minutes after swimming in water contaminated with cercariae, the skin in the areas where helminth larvae have penetrated (most often: shins, thighs, buttocks) turns red, with tingling, burning, and itching sensations. Later, a rash appears, and body temperature may rise. After 2-3 days, the itching begins to subside, but the rash remains for several more days. Sometimes, affected individuals experience weakness, dizziness, and sleep disturbances; in severe cases, fever and dry cough may occur.
To relieve itching, apply gauze pads soaked in a soda solution (one teaspoon per glass of water) to the affected areas. Anti-itch ointments and gels containing an anti-allergic component can also be used. If the itching is very severe, it is necessary to consult a doctor.
To avoid infection, it is necessary to remember and follow these rules:
- Do not feed wild waterfowl in areas designated for swimming;
- Swim at specially equipped beaches, away from clusters of freshwater snails and nesting sites of waterfowl;
- Stay in the water for no more than 5-10 minutes (to protect the skin from larval penetration, it can be lubricated with nourishing creams and oils or petroleum-based repellents);
- Upon exiting the water, rinse with tap water, or if this is not possible, dry yourself thoroughly with a towel (especially the shins and thighs).
Epidemiologist N. Pobortseva