RESUMEN
The aim of this study was to examine the effect of a primary patent Schistosoma japonicum infection on the establishment and location of a superimposed Ascaris suum infection in pigs. The study comprised two experiments each containing two groups of pigs. In the first experiment, 7 pigs were injected intramuscular (i.m.) with 800 S. japonicum cercariae and inoculated with 1,000 A. suum eggs 11 weeks post primary infection (ppi) and 8 pigs were inoculated with 1,000 A. suum eggs at the time of challenge infection. In the second experiment, 7 pigs were injected i.m. with 1,100 S. japonicum cercariae and inoculated with 1,000 A. suum eggs 16 weeks ppi and 8 pigs were inoculated with 1,000 A. suum eggs at the time of challenge infection. All pigs were slaughtered 10 days after the A. suum challenge infection. The number of white spots caused by A. suum on the surface of the liver was significantly lower in the groups with primary infections of S. japonicum compared with the control groups. However, the present experiments did not demonstrate any effect of a primary S. japonicum infection on the total recovery and distribution of an A. suum challenge infection.