Although swimmers’ itch has been known to exist for more than a century, it was not until 1928 that a biologist found that the dermatitis was caused by the larval stage of a certain group of parasitic animals. As illustrated in Figure 1, these parasites must cycle through snails and birds or mammals. Since the original discovery, it appears that reports of swimmers’ itch in Michigan have been on the increase. The following are possible reasons for this: (a) there appear to be more birds that serve as final or definitive hosts; (b) recreational demands have resulted in the construction of more lakes and ponds; and (c) more people are aware of the condition of swimmers itch and do not confuse it with other skin ailments like chiggers, poison ivy, chicken pox or mosquito bites.