One common misconception about swimmer's itch is the idea that it can spread across the body or from person to person. In reality, swimmer's itch is not contagious in the way many believe. The condition is caused by cercariae, the larval stage of certain parasites, which penetrate the skin during contact with infested water. The reaction, characterized by the formation of papules, is localized and occurs only where a cercaria has made its entry.

Each papule represents a separate cercarial entry point into the skin. Therefore, the appearance of multiple papules indicates multiple exposures or entries, not the spread of the condition across the skin from a single entry point. Swimmer's itch is a direct result of cercariae penetrating the skin, and its occurrence is limited to the areas of direct exposure.

Understanding this mechanism is crucial for managing and preventing swimmer's itch. Awareness that the condition does not spread from one papule to another or from person to person can help in addressing concerns and implementing effective preventive measures, such as rinsing or drying off immediately after exiting infested waters.