Swimmer's itch presents a perplexing challenge, mysteriously flaring up one year only to vanish the next. This phenomenon is not arbitrary but influenced by a complex interplay of environmental and biological factors that can shift annually. The presence of swimmer's itch in a lake is contingent upon several variables:

• The distribution and abundance of snails that act as intermediate hosts for the parasite.
• The number and type of bird hosts needed for the adult worm's survival.
• Wind direction and water currents, which can spread or concentrate parasites.
• The duration of exposure, with longer periods increasing infection risk.
• The time of day, as certain periods may see higher parasite activity.
• An individual’s sensitivity to the itch, varying greatly among swimmers.

Each factor plays a critical role in the lifecycle of the parasites responsible for swimmer’s itch, and fluctuations in any of these can significantly impact the likelihood of an outbreak. Consequently, the shifting dynamics of nature and human interaction with water bodies make swimmer’s itch a variable and unpredictable nuisance, highlighting the delicate balance within our ecosystems.