1.Water centrifugal sedimentation is a simple rapid method of stool examination for detecting eggs of Schistosoma japonicum in the stools of infected patients.
2.This method requires no chemical reagents and only a minimum amount of standard laboratory equipment.
3.In our experience it was more efficient than direct smear examination of stool material free of grossly visible bloody mucus, or examination by acid-ether, zinc sulfate, or brine flotation. Viability of eggs found after treatment can be determined.
4.Direct smear examination of mucus present in some stools revealed a high percentage of positives for S. japonicum in such material. Occasionally, trophozoites of E. histolytica were also found in this material.
5.Water centrifugal sedimentation done repeatedly in the course of the diagnosis of suspected schistosomiasis or for evaluation of specific therapy will frequently detect the presence of other protozoa and helminths in addition to S. japonicum.
6.In our experience in these studies the stool method of choice in the study of schistosomiasis japonica patients was as follows:
(a)Careful visual examination of the gross stool for the presence of bloody mucus. Direct smear examination of this material if present.
(b)Water centrifugal sedimentation of all specimens not containing grossly visible bloody mucus and specimens negative by direct smear of bloody mucus if present.
(c)Routine zinc sulfate and brine flotation for the detection of protozoa and helminths other than S. japonicum which may or may not be found by water centrifugal sedimentation, and which may be present in a high percentage of patients under observation for schistosomiasis japonica.
7.From 20 to 30 stool examinations during a period of 4 to 6 weeks were required to detect light asymptomatic infections in a group of patients exposed on Leyte. Eggs had not been detected previously in any of these individuals and none had received treatment.
8.Stool examinations should be begun 30 days after completion of treatment and continued for 8 to 10 weeks, 3 stools weekly. Most treatment failures are discovered from 5 to 12 weeks after completion of therapy with fuadin or tartar emetic.
In the interval between these studies at Moore General Hospital and the present, numerous techniques have been introduced which were designed to increase the probability of detecting eggs of schistosomes. These methods are critically evaluated in a recent review by Stoll (37). In follow-up studies of schistosomiasis japonica in veterans and prisoners of war subsequently to be reported we have carried out most of these techniques. The method we now use is a combination of alcohol sedimentation, (38) hatching, and treatment of the alcohol sediment with ether, hydrochloric acid, sodium sulfate and Triton NE. (39).