The egg-laying capacity of clonorchis sinensis. ∗

Abstract

Evidence presented from our investigation indicates that egg-laying in Clonorchis sinensis is neither periodic nor irregular, but is a continuous process, beginning as soon as the worm matures and probably continuing until the death of the worm. Variations in the number of eggs in the stool are due to irregularities in fecal output of the host, to differences in consistency of the stool, and to temporary lodgement of eggs in the bile tracts or gall bladder, and are not due to actual differences in egg-production per unit of time. Mature worms in recently acquired infections have the same egg productivity as worms that have resided in a host for many months. In a given species of host egg-production per worm unit of time is constant. There is, however, a difference in egg-production in different species of hosts, apparently independent of the size of the host. For this reason data on the relation of Clonorchis egg-production to the number of worms present in experimental mammals are not directly applicable in human cases of Clonorchis infection. Reckoning from the relation of the average number of eggs per worm per day found in the host's feces to the number of worms found at autopsy of the host immediately after egg-counts have been completed, the average egglaying capacity of Clonorchis sinensis in the cat is 2400; in the guinea pig, about 1600; while in the dog it is estimated at about 1100.

Data are presented to show that calculatim of Clonorchis worms present in the bile passages, based on the average number of eggs per worm per diem in an infection in a particular species of host are more reliable than those based on the average number of eggs per gram of feces (Stoll method).