Hymenolepiasis(redirected from Hymenolepis nana)
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a helminthic disease of man, mammals, and some birds; one of the cestodiases. In man, hy-menolepiasis generally results from infection by the dwarf tapeworm, occasionally by the rat tapeworm. Hymenolepiasis is widespread, especially in subtropical and tropical countries; it occurs chiefly in cities. A characteristic of the way the disease spreads is that the incidence is highest in those regions where few or no cases of ascariasis occur.
Children are the chief sufferers, becoming infected after ingesting the parasite’s eggs that are present on dirty toys, hands, and so forth. When the eggs of the dwarf tapeworm reach the small intestine, onchospheres are released from the eggs, and in five to eight days cysticercoids (larvae having a head with suckers) emerge from the onchospheres and attach themselves to the intestinal wall, causing edema of the mucous membrane, disruption of the blood circulation, necrosis, and sometimes hemorrhages into the lumen of the intestine. The segments of the tapeworm mature quickly and release into the lumen numerous eggs that subsequently appear in the stools (19 days after infection). The eggs remain viable for several days in soil and up to a month in water.
Hymenolepiasis is manifested by abdominal pain, loss of appetite, diarrhea, headache, irascibility, insomnia, retarded development in children, and decreased capacity for work in adults. Treatment consists in administering anthelmintics and, in addition, supporting treatment (vitamins and iron preparations). Prevention consists in observing the rules of personal hygiene at home and in children’s institutions and providing children with nutritional food containing an adequate amount of vitamins.
Hymenolepiasis in poultry. Hymenolepiasis in ducks and geese is very common everywhere; it occurs less often in chickens. The animals become infected in the spring when they eat infested intermediate and reservoir hosts (such as water fleas, gammarids, and pond snails). The cestodes injure the mucous membrane of the intestine and interfere with its peristaltic and secretory activity. If large accumulations of the parasites occur, they may obstruct the intestine. Sick birds grow and develop poorly, and the young sometimes die. The diagnosis is based on the results of dissecting dead birds, when an account is taken of the pathological changes observed.
Kamala, bithionol, and filixan are a few of the agents used to treat the disease. Preventive measures include raising the young and adult birds separately and raising marketable poultry (ducks and geese) on dry land and chickens in cages. Bodies of water are disinfested by keeping birds away from them for one to one and a half years.