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
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