The control of necrotic enteritis in sucking piglets by means of a Clostridium perfringens toxoid vaccine.

Necrotic enteritis in sucking piglets constitutes a serious problem in piglet rearing units because of the high morbidity and mortality associated with the disease. The primary causal agent is Clostridium perfringens type C. The beta-toxin plays a decisive role in the pathogenesis of this disease. A toxoid vaccine for use in sows has been developed and studied in field trials. The European Pharmacopoeia Monograph on vaccines for use in animals lays down a method of the efficacy testing based on the immunization of rabbits, the collection of pooled sera and the subsequent assay of anti-toxin antibodies in mice using an appropriate test toxin. The vaccine is regarded as effective if it induces a minimum of 10 IU of beta-anti-toxin per ml of rabbit serum. We have established a range of 17.14-98.23 IU beta-anti-toxin per ml rabbit serum induced by a sample of C. perfringens toxoid vaccine. The vaccine has been used under field conditions in different rearing units at the same time, mostly in the form of emergency vaccinations following the outbreak of disease. The outcome of vaccination was evaluated by recording the total numbers of piglets born alive and the piglet losses. Use of the vaccine, coupled with other measures, resulted in an approximately 30% reduction in the number of losses.