Concurrent Ascaris suum and Oesophagostomum dentatum infections in pigs

The aim of this study was to examine interactions between Ascaris suum and Oesophagostomum dentatum infections in pigs with regard to population dynam ics of the worms such as recovery, location and length; and host reactions such as weight gain, pathological changes in the liver and immune response. Seventy-two helminth-naive pigs were allocated into four groups. Group A w as inoculated twice weekly with 10000 O. dentatum larvae for 8 weeks and su bsequently challenge-infected with 1000 A. suum eggs, while Group B was inf ected with only 1000 A. suum eggs; Group C was inoculated twice weekly with 500 A. suum eggs for 8 weeks and subsequently challenge-infected with 5000 O. dentatum larvae, whereas Group D was given only 5000 O. dentatum larvae . All trickle infections continued until slaughter. Twelve pigs from Group A and B were slaughtered 10 days post challenge infection (p.c.i.) and the remaining 12 pigs from the each of the four groups were slaughtered 28 days p.c.i.. No clinical signs of parasitism were observed. The total worm burd ens and the distributions of the challenge infection species were not influ enced by previous primary trickle-infections with the heterologous species. Until day 10 p.c.i. the ELISA response between A. suum antigen and sera fr om the O. dentatum trickle infected pigs (Group A) pigs were significantly higher compared to the uninfected Group B. This was correlated with a signi ficantly higher number of white spots on the liver surface both on Day 10 a nd 28 p.c.i. in Group A compared to Group B. The mean length of the adult O . dentatum worms was significantly reduced in the A. suum trickle infected group compared to the control group. These results indicate low level of in teraction between the two parasite species investigated. (C) 1999 Elsevier Science B.V. All rights reserved.