Cellulitis continues to cause extensive losses in turkey production in USA due to severe mortality, carcass condemnation and treatment costs. Clostridium perfringens and Clostridium septicum have been recognized as the primary causative agents of cellulitis in turkeys. In this study, cellulitis lesions and mortality in turkeys were successfully reproduced with Clostridium perfringens and Clostridium septicum isolated from cellulitis cases. Clostridium perfringens and Clostridium septicum isolates varied in their ability to produce spores as well as toxins. We observed differences in the toxicity and biological effects of different strains of C. perfringens and C. septicum in vitro, and in vivo. Though the spore count and hemolytic effects of C. perfringens were found to be higher than C. septicum in vitro, mortality studies in mice and turkeys showed that C. septicum was much more potent than C. perfringens. However, gross lesions produced by C. perfringens and C. septicum were almost identical. Surprisingly, the development of cellulitis lesions and mortality was markedly higher in 7-week-old birds than in 3-weekold birds. The results of our study demonstrated for the first time that both C. perfringens and C. septicum can multiply in the subcutaneous and muscle tissues and cause cellulitis lesions in turkeys. Our cellulitis disease model offers promise as a challenge model in the development of vaccines against cellulitis in turkeys. Both bivalent C. perfringens and C. septicum toxoid and C. septicum toxoid were found to be safe and offered complete protection against cellulitis following homologous challenge under experimental conditions. The use of these vaccines enabled us to reduce the mortality and antibiotic usage in preventing cellulitis in commercial turkeys. Multiple vaccinations or use of a day old vaccine followed by a booster dose probably will offer better protection than a single vaccination at 6-weeks of age against cellulitis due to C. perfringens and C. septicum in turkeys.
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