SCREENING METHOD FOR ORAL ANTIBILHARZIAL DRUGS IN MICE

The present report deals with a preliminary screening method for new drugs in prophylactic or therapeutic treatment of experimental schistosomiasis japonica. The dosage selected in the screening was calculated according to the result of a 3day toxicity test of 6 mice. In the preliminary prophylactic screening test, mice were treated orally from the day of infection for 14 days and were autopsied at the end of treatment. The schistosomula in the liver were collected by perfusion method and their lengths were measured. The drug may be considered effective in suppressing the growth of schistosomula if the mean length of the worms in the control group is twice that of the test group and a certain proportion of the schistosomula in the treated group is less than 300 micron in length. In a preliminary therapeutic screening test mice were treated one month following exposure to cercariae for 5—7 days, Mice were killed the day after withdrawal of the drug. The flukes were washed out and examined for changes in size and intestinal pigment content. The drug is considered to be active if the worms decreased in size and in their pigment content.