Outbreak of Bovine Botulism in Holstein and Korean Native Cattle in Korea

Background: Clostridium (C.) botulinum is ubiquitous in soil and cause a disease in human beings and animals that ingest food or feed contaminated with toxin or the bacteria. They produce 7 serologically distinct toxins, namely A, B, C, D, E, F and G. Bovine botulism is recognized worldwide and occurs with the feeding of toxin-contaminated feed, poultry wastes, and poorly processed forages. We report here on botulism in 5 herds fed large round hay that was packed with plastic following harvest. Methods: In September 2011, 220 Holstein and 40 Korean native cattle from 5 herds located in northern part of South Korea were shown to recumbency, limb parlaysis, impossible to stand up, and death. The carcasses were submitted to QIA and necropsied. Histopathologic, blood chemistry, viral and bacterial examination were performed. Sera, feces, TMR feed and plastic packed hay were subjected to isolation of bacteria and mouse neutralization test according to CDC manual for botulinum. After incubation, the suspected colonies were subjected to PCR to determine the toxin type. Results: There were no specific signs in necropsy. Viral and bacterial pathogens were not detected. The levels of blood chemistry were normal except creatine kinase. Histopatologically, pchymeningitis with eosinophilic vasculitis were shown in spinal cords. In mouse neutralization test, the toxins of C. botulinum type B and C were detected with sera from 4 and 1 herds, respectively. C. botulinum type D was also detected in plastic packed hay and water trough in the other herd. Although toxins (B, C, and D) were detected from sera, hay and water, the bacteria were not isolated from environmental samples including feed, hay and water. The outbreak was discontinued after disposal of plastic packed hay in those farms. Conclusion: Bovine botulinum was diagnosed in Holstein and Korean native cattle using mouse neutralization test. The disease usually occurs as sporadic cases, but in intensively farmed animals. Most cases of botulinum in cattle have been associated with ingestion of materials containing pre-formed toxins. In this study, plastic packed hay would be suspected to be a cause of botulism in Holstein and Korean native cattle.