What causes swimmer's itch?

Swimmer's itch, also known as cercarial dermatitis, is caused by waterborne parasites, specifically the larvae of certain trematodes (flatworms) that primarily infect birds and mammals. When these larvae are released into the water from infected animals, they may come into contact with humans who are swimming or wading in infested water. If the larvae penetrate the human skin, they cause an allergic reaction that leads to the characteristic itchy rash.

The context behind swimmer's itch being caused by waterborne parasites is important to understand for environmental health professionals. Recognizing the transmission pathway helps in developing strategies for prevention, such as informing the public about the risk of swimming in certain water bodies, particularly those known to be infested with these parasites. Awareness of the life cycle of these parasites is also essential for managing public health around recreational water use.

Other options, while they may lead to other health issues, do not fall under the cause of swimmer's itch. For instance, waterborne viruses are typically associated with gastrointestinal illnesses, contaminated swimming pools relate to bacterial or chemical issues, and airborne allergens trigger allergic reactions but are not linked to swimmer's itch.