Hydatidose : aspects épidémiologique et diagnostique

Abstract

Objectives Description and epidemiology of a zoonose widespread in the world. Hydatidosis is a widespread zoonosis infecting a large number of animals and humans. Epidemiology Echinococcus granulosus has the smallest taenia adult of the cestodes in definitive hosts but with the largest larva in intermediate hosts. Its morphologic and biologic features were identified with DNA analysis. Different strains were separated according to the intermediate hosts: sheep, cattle, pigs, horses, camels. Definitive host are canids, mostly dogs, where the worm grows to adulthood in several months. The eggs are scattered in the pasture by wind, water and insects and are ingested by various hosts. The larvae migrate through the intestinal wall and penetrate the organs, mostly liver and lungs. The eggs survive several days outside, depending on the temperature, but numerous eggs die in nature because they cannot resist desiccation and extreme temperatures. Incidence and clinical profile in man Dissemination is accomplished by dogs. In Turkana (Kenya) the incidence of hydatidosis is high because of the close relationship between the population and dogs and the habit of leaving their dead bodies in the grasslands. In rural areas, the custom of slaughtering sheep at home, among the dogs, is an important dissemination factor. The circumstances of transmission vary according to the country. In Europe, the natural life cycle of E. granulosus granulosus involves dogs as the definitive host and sheep as the intermediate host. In northern Europe, E. granulosus borealis infects the canids and deer. E. granulosus canadensis infects wolves and reindeer, but there are no human cases. Diagnosis Symptoms are different, according to the location of hydatidosis (liver, lung, heart, kidneys, bones, muscles…). Diagnosis of hydatidosis is obtained by radiology and immunologic tests. Treatment and prevention The standard procedure is surgical removal of the cyst, sometimes with albendazole during several months or years. Control must interrupts the life cycle, by periodically deworming domestic dogs, and destroying carcasses of dead animals. In several countries, (Tasmania, Cyprus) an intensive control promptly interrupted transmission of echinococcosis in man and animal.