Tetanus outbreak in a sheep flock due to ear tagging

Area of Science:

• Veterinary Medicine
• Infectious Diseases
• Microbiology

Background:

• Tetanus, a fatal neuromuscular disease caused by Clostridium tetani, affects farmed mammals.
• Outbreaks are typically linked to wounds contaminated with C. tetani spores.

Observation:

• An outbreak of tetanus occurred in a sheep flock following ear tagging procedures.
• Affected sheep exhibited neurological signs including convulsions, limb stiffness, incoordination, and trismus.
• Clinical signs included tachycardia, dyspnea, mild fever, muscle rigidity, and anxiety.

Findings:

• Wounds and scabs were observed at ear tag sites.
• Gram-positive bacilli with terminal spores, identified as C. tetani, were isolated from ear wounds.
• The initial case fatality rate was 50%, declining significantly after procaine penicillin G administration.

Implications:

• Contaminated ear tagging instruments likely introduced C. tetani spores.
• Ear wounds created anaerobic conditions favoring C. tetani germination and toxin production.
• Standard hygienic practices during animal procedures are crucial to prevent tetanus, even in vaccinated animals.