IMMUNIZATION OF PIGS AGAINST INFECTION WITH SCHISTOSOMA-JAPONICUM USING ULTRAVIOLET-ATTENUATED CERCARIAE

Since pigs are important in the zoonotic transmission of schistosomias is japonica in China, a veterinary vaccine might contribute to the con trol of the disease in humans, Pigs were immunized with three doses ea ch of 10000 cercariae of Schistosoma japonicum attenuated with ultravi olet light (400 muWatt-min/cm2). The experiment was performed with por table irradiation equipment in a rural area of the Hubei Province (P.R . China). A challenge infection of 1000 untreated cercariae was given 2-5 or 6 months after the last immunization, and age-matched naive pig s were challenged as a control. Immunized pigs developed about 90% res istance against the challenge. The liver egg load of these animals was reduced by over 90%. Less than 0.01% of the immunizing cercariae deve loped to adult parasites and the vaccination had no apparent adverse i nfluence on the pigs' health.