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Show Eye Parasite Affecting Utah Fish, Study Shows A parasitic eye fluke which causes blindness in fish ("fish cataract disease") is on the Increase in Utah, according to two Brigham Young University scientists. The disease known as larvae of an organism called Diplostomum spathaceum which destroys eye tissues. Studies at Strawberry Reservoir In Wasatch County show infections in rainbow trout rose from 75 percent In June to 98 percent In November Cutthroat trout infections rose from 48 percent in June to 67 percent In August Dr James R. Palmier!, a parasitologist doing postdoctoral research at BYU, and Dr Richard A. Heckmann, associate professor of zoology and a specialist in Ichthyology, said a sample study at Otter Creek Reservoir In Piute County last August showed 100 percent ot the rainbow trout were Infected and a sampling at Nine Mile Reservoir near Mantl in December showed about 95 percent of the rainbows were infected. Outbreaks have also been reported in Colorado, North Dakota and Washington. "The disease is much more prominent than we thought, and it is on the increase," Dr Heckmann said. "It is very possible that higher mammals including man could become infected with the eye-localizing fluke." He said research by other scientists indicates the fluke can live in the eyes of reptiles, amphibians, birds and mammals. Dr. Palmieri said he is studying a special protozoan parasite which might control the disease by attacking the fluke before it gets into fish. Unlike other proposed control methods such as chemically treating the water, the protozoa do not harm animal or plant life. This protozoan has proven successful in laboratory experiments in Michigan, and Dr. Palmieri hopes to find how effective it is in ponds, reservoirs and lakes. Dr. Heckmann explained that the disease occurs only in reservoirs and lakes not in running steams. The life cycle begins when the eggs pass from the intestines of fish-eating birds such as gulls into reservoirs or lanes, Free-swimming larvae ' develop in two to three weeks ' and penetrate the livers of snails. Within six weeks these sporocysts release free-swimming organisms (cer-cariae) which penetrate the gills, skin and eyes of fish, he said. Sometimes fish acquire the flukes directly by eating snails. The flukes migrate through the blood stream to the eyes and eventually cause the lenses to become opaque, thus blinding the fish. In some cases where as many as 400 to 1,000 flukes have been found in one eye, tne eye ruptures. Eventually the birds eat the infected fish and this completes the life cycle ot the fluke. Drs. Heckmann and Palmieri plan to survey lakes and reservoirs throughout Utah to determine the full extent of the disease, and they hope to develop effective means of controlling it through the use of the special protozoan. "The disease poses a serious threat to Utah's fish population, especially to trout," Dr. Heckmann s-atd. "It might also present a health hatard to man." Fish-Eye Disease Study Dr. Richard A. Hrckman, left, and Dr. James R. Palmieri study photographs related to their research on a fish cataract disease which appears to be on the Increase In some ot Utah's lakes and reservoirs. The disease blinds fish. |