Furthermore, there is evidence that infected snails may go down to a depth of at least 10 meters so deeper water is not a reliable way to prevent swimmer’s itch.
It is likely that there are fewer cercariae in deeper water but water currents, wave action and off shore winds may distribute cercariae to other regions irrespective of where the cercariae originated. Once that happens, it is too late.Īnother suggestion for reducing swimmer’s itch is for swimmers to go to deeper water, away from infected snails. In fact, some people can feel a “pricking” sensation when the cercariae penetrate.
#Swimmers itch guard skin#
Today the great majority of cases of swimmer’s itch is caused by cercariae that penetrate the skin while a person is in the water. This advice was introduced decades ago when a few unimportant species were thought to cause swimmer’s itch. The most common one is advising swimmers to “towel off” and or shower immediately after leaving the water. Unfortunately, these myths continue to be perpetuated on line, on signs posted at the beaches, and by lake association newsletters. Subsequent exposures usually cause a more severe reaction and children and adults with fair complexions, are usually affected the most.ĭuring the past half century, many myths have resulted from attempts to reduce the adverse effects of swimmer’s itch. There is often a reduced reaction when someone is exposed for the first time. It is now called a papule that will itch intensely for up to two weeks. Within 30 hours, this area of the skin becomes much larger in diameter and then becomes reddened and raised. In sensitized people, the cercaria enters the epidermis and dies. In birds, they continue to enter their natural hosts and develop into adult worms. If the cercariae come in contact with a person, they will penetrate the epidermis(skin) however, in people, they do not have the proper enzymes to proceed further, so they die. Size of snail, age of the infection and water temperature are important factors in determining how many cercariae are released each day. This process is repeated daily for each snail from the late spring to early fall. These forms, living for nearly 24 hours, are dispersed by wind and wave action. The number of cercariae released each day can be up to several thousand. About a month later, the end products (cercariae) are released daily, usually early in the morning, stimulated by light. Once in the snail, the miracidium migrates to an internal organ, changes to form a network of tubes (sporocysts) that begin reproducing at an incredible rate. The miracidium does not enter just any snail, but members of a single species. When it gets closer, there appears to be a chemical attraction emitted from the snail which leads to the miracidium penetrating the snail.
Upon contact with water and light, a ciliated form (miracidium) hatches and swims in a zigzag pattern hoping to contact a specific species of snail. The microscopic-sized worms lay eggs that work their way into the lumen of the intestine of the vertebrate host (duck) so that they can be passed out with the feces. Swimmer’s itch is a skin reaction by sensitized people, to a larval stage (cercaria) of a group of flatworms whose adults usually live in the veins associated with the intestine of its vertebrate hosts (waterfowl and mammals that live in or near the water).
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