Circumoval precipitin (COP) test using air-dried eggs of Schistosoma japonicum and S. mansoni.

In an attempt to establish a simplified circumoval precipitin (COP) test for the diagnostic purpose of schistosomiasis, air-dried eggs of both Schistosoma japonicum and S. mansoni were tested as antigens for this assay. Twenty-six sera from mice infected with S. japonicum showed positive COP reactions as assessed by air-dried eggs. Among 36 serum samples from patients with schistosomiasis japonica, five exhibited false negative reaction when assessed with air-dried eggs and showed a minimum level of COP reaction when assessed with lyophilized eggs. Similarly, all of 30 serum samples from jirds (Meriones unguiculatus) infected with S. mansoni gave positive COP reaction when assessed using air-dried egg. Diagnostic sensitivity of air-dried egg-system was comparable to those of fresh egg-or lyophilized egg-systems. A simple COP technique employing air-dried eggs, instead of lyophilized or fresh ones, would be thus useful for the serodiagnosis of schistosomiasis in local endemic areas, where sophisticated laboratory facilities are not available.