Serodiagnosis of suspected echinococcosis cases using native, partiallypurified, and recombinant antigens

Abstract

Echinococcosis is a rare disease in Thailand. All suspected cases were either serodiagnosed or parasitologically tested for the infection. Indirect ELISA has been used to screen for negative results at the Department of Helminthology, Faculty of Tropical Medicine, Mahidol University. Twenty-four serum samples were from nonThai and Thai patients, and were collected from 1986 to 2003. All sera were tested to obtain positive results by indirect ELISA and immunoblot at the Department of Parasitology, Asahikawa Medical College, Hokkaido, Japan. Antigens from both Echinococcus granulosus and E. multilocularis were used, eg., cystic fluid (HCf/ sheep, AgB), fractionated cystic fluid of alveolar cyst (Em22F911 Ag, AEc) and recombinant antigen (rAgB). Only one Thai patient had higher ODs-ELISA (0.922, 1.140 and 1.386) than the positive controls (0.651, 1.121 and 1.358) against Em22F911 Ag, HCf/ sheep (AgB) and recombinant antigens, respectively. Antibodies of the rest produced lower ODs against three antigens, but one Thai patient had OD (0.633) against Em22F911 Ag close to that of the positive control. A Thai patient, in whom protoscolecies were found, had far lower ODs (0.440, 0.377 and 0.063) than controls against Em22F911 Ag, HCf/sheep (AgB) and recombinant antigen, respectively. Ten serum samples of high ODs-ELISA, (both higher and lower ODs than the positive controls), were tested specifically for antibodies against AgB of HCf/sheep by immunoblot. There were four suspected cases, two non-Thai and two Thai patients, and the protoscolex-positive case presented immunoblot-positive using this AgB. The investigation of echinococcosis detection is more successful in use of immunoblot than indirect ELISA.