Thirty-five Europeans who had had possible exposure to Clonorchis infection while in Shanghai in the 1940's, and who had been in this country since 1950 or before, and 5 persons of Chinese ancestry resident in this country for a similar period were examined for this parasite. In 24 of these 40 persons there was no clear evidence of past or present infection. Eight were found to be presently infected. These 8, and 4 of 5 with a known history of infection but who were no longer found to be passing eggs, were investigated by means of Stoll counts for intensity of infection and by various liver function tests for signs of hepatic damage.
Infections, ranging in intensity from those just detectable by means of concentration techniques to ones in which some 700,000 eggs were produced per 24 hours, were seen in 8 patients who had been in this country from 12 to 29 years. In none of these patients, and in none of the 4 with known previous infection, was there evidence of liver damage. It is concluded that treatment with any of the drugs now available is not warranted in these circumstances.