02-07-1977 Planning Packet - Laserfiche WebLink

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St .1 /• r .. •' 4 • it, -•' kes reporting prob- 1960-63, of which t 1964-67 the total hese were from the nsula. Part of the sporting swimmers* tors as an increased owing numbers of ■ of more and more tendency for many e done ” about the worthy that during rtion of Michigan latitis problems— the southern part es in the populous suggest that the suthward in recent n these southern ; Michigan Water ( is a “minor nui- leriod at the very IS been obtained ich a person may -causing cercariae ted from infected rm sunny days— are most favored :>nd positively to dimming actively penetrate the skin reed—if he stays igcr—or after he n to become air- 1 strong on-shore here are beds of cercariae may be ‘onlimued on pagt JO) ( m a ’I .2. Pa V-. • 2 - * I / * •1“ * ; ' I %•' ■'il h'jliJJ '■•r-■ V ■ > \ ' • > t A . i Vv . FVW I - i y-V 1: 'ili. f* . r >«« a • .• • * SWIMMERS' ITCH (continued) carried passively to the very shallo\v waters adjacent *bore where children or adults w*ho are swimming or playing may contract bad infections of dermatitis, while swimmers remaining in deeper water farther from shore remain largely unaffected. ^ Some individuals are very sensitive to the penetra tion of schistosome cercariae, others contract only mild cases of the disease, and still others appear to be immune. The body of potentially sensitive individ- duals usually becomes more sensitive, rather than immune, with repeated exposure to the cercariae. Schistosome dermatitis is, in essence, an allergic reaction by the body to the presence of a foreign protein —the cercariae. In areas where swimmers* itch is prevalent, con- ^iticrable attention has been given to measures by which it may be prevented, treated, or controlled. Methods of prevention include avoiding cercaria- ■ infested waters, or wearing clothing with a tight weave, or wearing waterproof boots or waders when entering such waters. Swimmers who remain in deep water while swimming and dry their skin briskly with • *owel immediately after leaving the water can minimize penetration by the cercariae. Once the cer cariae have penetrated, there is relatively little that can be doiie by way of treatment, although itching may be relieved somewhat through the use' of some soothing lotion. Methods of control which have been advocated include prevention of snail infection and destruction of snail intermediate hosts. The former method would involve protecting bathing beaches with a schis tosome dermatitis problem from flocks of migrating or domestic ducks (or other definitive hosts). It is suggested that if this were done in the fall, it might reduce or eliminate the dermatitis for the following season. However, more needs to be learned about what species of birds are the normal definitive hosts of dermatitis-producing schistosome cercariae before this could become an effective control method. The usual method of control has been to kill the snails harboring infections by chemical means. Copper sulfate has been used for this purpose for a number of years, in Michigan under permit from the State Water Resources Commission. Combinations of cop per sulfate and copper carbonate, and more recently of copper sulfate with hydrated lime, were found to be most effective and economical when applied under suitable conditions at the rate of 2 pounds per 1,000 square feet of area. Specialized equipment has been designed and is used regularly for this purpose in heavily infested areas. Large numbers of snails are killed, but not .snail eggs or cercariae released from the dying snails. This treatment is relatively harmless to fish in unconfined areas. Between 1939 and 1967 nearly million pounds of copper sulfate were authorized by the .Michigan Water Resources Com mission for use in swimmers* itch control programs in Michigan lakes. In 1939, 3,500 pounds were author ized: in 1967 over 87,000 pounds. The effectiveness of this method of control —while apparently considered satisfactory by many—has been seriously questioned by some people. Swimmers’ itch outbreaks continue to recur in infested lakes, often during the same season after copper sulfate treatment has been in stituted. Furthermore, copper sulfate accumulates in the bottom sediments of treated lakes, and no one knows the long-range effects of this accumulation. New mollubcicidesfmollusk-killers) have been devel oped and tested, and some have been found to be more effective in killing carrier snails and schistosome cercariae than is copper sulfate. One of these is sodium pentachlorophcnate, which has the drawback of being highly toxic to fish. Another goes by the trade name of Niclosamide (Bayluscide). This material is more effective in killing snails (and other mollusks such as large mussels) than is copper sulfate, and also will kill snail eggs and schistosome cercariae. It does not harm aquatic in.scct larvae or most fish when used at recommended dosages in a 5', heavy gianular for mulation. It docs not accumulate in bottom sediments as docs copper sulfate. It has been licensed for use in ■’S-.Vt vs i 1 It r • ' •% Michigan, planes, un Bureau of Resources One*s V control sw used or pr by how se regard it n lem. Othei the situatk lem at leas in Michiga many are i days or e More recei and depen< not using incurring e< as an excej is being dar of the Mich whose jobs problems a and authoi grams to ki lem is a sei an importa swimmers’ i to control it Granting may take o learn all we to predict oi involved in < to live grac keep the us effecting cor one probler more serious tion of our approach w\ more effecti< and more r; their widesp waters. If thi effcciN as a n new tcchnoU those pnvbici vironmcntal