OESOPHAGOSTOMUM SPP. IN PIGS - RESISTANCE TO REINFECTION

For a study on the occurrence of resistance to reinfection with porcin e nodular worm species: pigs were infected twice weekly with 1,000 inf ective larvae (L-3) Of Oesophagostomum quadrispinulatum for 8 weeks. A ll pigs, including noninfected controls, were then treated with fenben dazole. At 10 days after treatment, all pigs received a single challen ge inoculation of 5,000 L-3 of either O. dentatum or O. quadrispinulat um, respectively. Pigs were slaughtered at 6 weeks after the challenge infection for determination of their worm burdens. The pigs trickle- and challenge-infected with O. quadrispinulatum had significantly lowe r egg excretion levels (P < 0.01) and worm burdens (P < 0.05) than cha llenge control pigs, thus indicating some degree of host immunity agai nst the homologous challenge infection. No resistance to reinfection w as evident for the heterologous challenge infection. This study elucid ates further aspects of the interaction between nodular worm species i n the pig.