ABSTRACT
The circumoval precipition test (COPT) is a simple and inexpensive immunodiagnostic test for schistosomiasis japonica which, in the Philippines, has high sensitivity and specificity. Lack of standardization does, however, increase the variability of the test. Parameters which influence the COPT have been examined using large numbers of sera from known S. japonicum infected individuals. In this series of experiments, optimal conditions were determined to be as follows using 2 drops of neat serum and incubation at 37 degrees C in a sealed slide chamber; - approximately 100 eggs from 55 or 60 days infected rabbits for a 24 to 48 hour incubation period. COP reactions (i.e. precipitates associated with eggs) were much less obvious when either immature eggs or eggs obtained from long-term infected rabbits were used. The results emphasize the prime importance of the source of Schistosoma japonicum eggs in the performance of a standardized COPT.