Type C botulism outbreak in feedlot cattle fed contaminated corn silage

Area of Science:

• Veterinary Medicine
• Toxicology
• Animal Science

Background:

• Clostridium botulinum neurotoxin type C (BoNT/C) can cause severe outbreaks in livestock.
• Corn silage is a potential vehicle for botulinum toxin contamination.

Purpose of the Study:

• To report a large outbreak of botulism in feedlot steers in Brazil.
• To describe the clinical signs, diagnosis, and outcome of affected cattle.
• To highlight diagnostic and treatment challenges of bovine botulism.

Main Methods:

• Epidemiological investigation of an outbreak in 1700 feedlot steers.
• Clinical assessment of affected animals exhibiting flaccid paralysis.
• Diagnosis confirmed by characteristic clinical signs and mouse bioassay for BoNT/C.

Main Results:

• 1100 steers were affected by botulism after consuming contaminated corn silage.
• Mortality rate was extremely high, with 1090 deaths within four days.
• Ten steers recovered following antitoxin treatment; no gross or microscopic lesions were observed.

Conclusions:

• This outbreak demonstrated the severe impact of botulism in cattle, with a high mortality rate.
• On-site diagnosis and treatment with antitoxin were crucial but challenging.
• Effective prevention strategies, including proper silage management, are essential to avoid such devastating outbreaks.