Hydatid Disease in the Central Valley of California

Transmission of Infection among Dogs, Sheep, and Man in Kern County

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  • Department of Epidemiology and Preventive Medicine, School of Veterinary Medicine, University of California, Davis, California 95616

A sheep rancher in Kern County, California, a 49-year-old man of Basque ancestry, died after surgery for removal of two fertile, unilocular hydatid cysts from his left lung. This was the fourth reported case of hydatid disease in man autochthonous to California. This man's ranch, on which were stocked 2,500 to 3,000 sheep, was visited to discover whether sheep, dogs, and men were infected with Echinococcus granulosus. A dead sheep was found with an hydatid cyst of the liver, and 10 of 11 sheep dogs were found to be infected. Basque shepherds commonly dispose of sheep carcasses by feeding them to sheep dogs; evidently the dogs ingest hydatid cysts with scolices when they eat dead, infected sheep. Of 74 relatives, employees, and associates of the dead rancher who were skin-tested with hydatid-cyst antigen, eight had wheals of 1 cm2 or greater, which we consider positive. The serum of seven of these persons was tested by indirect hemagglutination; results for two suggested Echinococcus infection. Thus, the area in Central California in which transmission of E. granulosus is known to occur now extends for over 400 miles, from Tehama County in the north to Kern County in the south.

Author Notes

Present address: Centro Pan-Americano de Zoonosis, Ramos Mejía, Provincia Buenos Aires, Argentina.

Dr. Clérou practices general medicine in Bakersfield, California.

Present address: Veterinary Laboratory Services, California State Department of Agriculture, Sacramento, California.

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