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?/r ^ <br />wcr than one percent <br />is the large, recrea- <br />are most often af- <br />* itch have adversely <br />orts, inconvenienced <br />’ators, spoiled some <br />created temporary <br />To these people, <br />tch and its control <br />nnesota, Wisconsin, <br />evinces of Canada, <br />i from many parts <br />imers’ itch follows <br />itcr-borne larvae — <br />ic flatworms. Sn»all <br />after a few hours <br />rated, and are ac- <br />nsation which may <br />about twenty dif- <br />(blood flukes) are <br />an and produce a <br />itize certain birds <br />>riae mature into <br />mal, “accidental, <br />the human skin, <br />her. <br />lood flukes which <br />l normally —there <br />* % <br />. •• <br />THE <br />BIOLOGT <br />OF <br />PHILIP T. CLAMPITT <br />Associate Zoologist <br />Cranbrook Institute of Science <br />WetCraf/on* Odit <br />The LIVES of people, snails, waterfowl, and blood <br />fteh " x!" <br />hi! . der»,aH,ls. <br />P«*mial imerest to f rt <br />h “Pf*' regionb Michigan, at least, there is some esidence tha <br />le " "■* ho! <br />the -S" rV"** *~S”Phic <br />.K ^ '**" spreading southward. <br />Olw latelwl P^resit-OlOfy, waterfowl, swimming, duck huniine tourism <br />Iww reason tc be concerned-ai least indirectly- <br />Whjwmniers itch, and may thus want to learn more <br />htichigan Water Resources <br />J^mmission, Ihe Cause and Control of Swimmers’ <br />I«rt in hlichigan" (1969). gives a useful perspective <br />on the swimmers itch problem as follows: <br />lumbering days <br />bathers have been aware that itching rashes oc- <br />ttsiona ly developed following swimnnne in certain <br />areas. As recreational u.se of .Michigan-; lakes has <br />increased, more people have encountered this rash <br />known popularly as swimmers' itch and medically <br />as schistosome cercarial dermatitis. Alihouvh it <br />IS eslimaicJ that swimmers' itch has been reported <br />swimmers- itch have adversely <br />aflwfcd the income of some resorts, inconvenienced <br />cottage owners and camp operators, spoiled some <br />precious family vacations, and created temporary <br />discomfort for affected bathers. To these people <br />the importance of swimmers’ itch and its control <br />cannot be overstated.” <br />‘s also common in Minnesota. Wisconsin, <br />northern Iowa, and the central prov inces of Canada. <br />ofthr.!o!w <br />The rash associated with swimmers’ itch follows <br />peneyalion of the skin by tiny water-borne larvae- <br />^led cmar„if~or certain parasitic Baiwornis. Small <br />ni pustules appear on the skin after a few hours <br />wherever the ccrcariac have penetrated, and are ac ­ <br />companied by an inicnsc itching sensation which may <br />Iasi for several days. Ccrcariac of about twenty J. <br />k!!!Il!, . whisiosomc worms (blood flukes) are <br />rash. These worms normally parasitize certain birds <br />adultT?o1!d n'l "’“‘“re into <br />hit Afi^? ft. - “•’"‘""’“I. "accidental."hmt. After the cercan.ic penetrate the. human skin <br />they die rather tlian developing further. <br />dbrn ''■‘l!’"'' 'P""'’ •’'"'X' "<<I‘CS whichdo mature tn man but which do not norinally-thcrc <br />■re exceptii <br />penetrating <br />tosomiosiSt <br />disease infe <br />Africa, and <br />continental <br />The life c <br />typically inv <br />times mamr <br />Both snail a <br />pletion of t <br />intermediate <br />parasite take <br />host in whic <br />adult flukes <br />^v'.' <br />‘Jir <br />(about 1/5 of <br />y most flatworr <br />• *-• •.tissues of the <br />adult female f <br />-i ■■'reach the inte: <br />feces. Each eg <br />o . <br />produces a vei <br />• ’ ‘ <br />of an inch lonj <br />‘ »swims and dri <br />intermediate h< <br />■”* >If the miracidi <br />species, it devel <br />five tissues of t <br />after several we <br />V . <br />■ »•cercaria larvae. <br />■ V ”, <br />all happens at tl <br />■m;'/ •without normal <br />a parasite kills <br />- ff parasite. A “goc <br />V.point of view—1 <br />•1 not until the pa <br />?•where its host i <br />temperature and <br />the snail and beg <br />‘ 1 oercaria’s turn r <br />» <br />«a water bird (or <br />species of parasiti <br />■if the life cycle : <br />Jk <br />succeeds in flndin <br />$ * •with the aid of <br />0 migrates through <br />pf -•«vessels of the liver <br />V and matures into; <br />•After mating, the 1 <br />f \ <br />%begins again.