Detection of Coproantigens by Sandwich ELISA in Rabbits Experimentally Infected with Fasciola gigantica

BACKGROUND: The study was targeted to report the appearance of coproantigens in feces and circulating antibodies in the serum of Fasciola gigantica experimentally infected rabbits. METHODS: Copro Hyper Immune Serum (HIS) and Excretory-Secretory Hyper Immune Serum (ES HIS) antigens were used in a sandwich ELISA for the detection of F. gigantica antigens in feces of 12 rabbits experimentally infected with different doses of F. gigantica encysted metacercariae (EMC) (10, 25 and 30 EMC). The relation between time of appearance of coproantigens in feces and anti-Fasciola antibodies in serum was evaluated. RESULTS: The earliest diagnostic coproantigen was recorded at 21(st), 25(th) and 28(th) day post-infection (p.i.) in groups of rabbits infected with 30, 25 and 10 F. gigantica EMC respectively. Both HIS and ES HIS were able to detect coproantigens in feces of rabbits infected with 30 EMC at day 21 p.i. The appearance of F. gigantica coproantigens in feces of infected rabbits was concurrent to the appearance of anti-Fasciola antibodies in blood (3(rd) week p.i.). However, coproantigen has specific ability for direct assessment of active infection with minimal cross-reaction with other heterologous parasitic infections. CONCLUSION: The findings hold promise for a more accurate diagnostic technique in the near future for suspected Fasciola infection.