Schistosomiasis japonica in Barrio San Antonia, Basey Samar, in the Philippines: III. The plasma circumoval precipitin test-procedure and use in epidemiologic studies.

A plasma circumoval precipitin test is proposed as the basic diagnostic tool for epidemiologic studies on schistosomiasis japonica in the Philippines. The collection of plasma, the preparation of the COP test slide, and the reading and interpretation of results are described in detail with pertinent comments. The cost, advantages and usefulness of the test are also discussed.

Schistosomiasis japonica in Barrio San Antonio, Basey, Samar in the Philippines: II. Quantitative fecal examination and circumoval precipitin tests.

An improved quantitative stool examination technique (MFCT) and two variations in the performance of the circumoval precipitin test, one using whole serum (SCOPT) and the other employing the eluate from finger prick blood dried on filter paper (FPCOPT), were evaluated in a field study to detect infection with S. japonicum among residents of an endemic barrio in Samar. The sensitivity of SCOPT was above 90%, that of MFCT was between 80 to 90%, while that of FPCOPT was only about 50%. Intensity of infection as judged by fecal egg excretion and duration of infection as indicated by age were shown to be determinants of serum reactivity (and hence sensitivity of the two serodiagnostic tests). The relative insensitivity of FPCOPT observed in this work, also evident in some published data of previous workers, puts to doubt the wisdom of using this technique as the procedure of choice in epidemiologic surveys in the Philippines as currently favored in that country. Atypical positive reactions in circumoval precipitin tests using whole serum were detected which may make the differentiation of relatively recent from old infections possible.