Longitudinal study to investigate VTEC O157 shedding patterns in young cattle

Area of Science:

• Veterinary Microbiology
• Food Safety
• Animal Health

Background:

• Verotoxigenic Escherichia coli O157 (VTEC O157) is a significant foodborne pathogen.
• Youngstock are a key reservoir for VTEC O157 transmission in cattle herds.
• Understanding shedding patterns is crucial for effective control strategies.

Purpose of the Study:

• To investigate the shedding patterns of VTEC O157 in youngstock over an 11-month period.
• To assess the variation in VTEC O157 shedding at the individual animal, herd, and temporal levels.
• To evaluate the implications of shedding patterns for intervention strategies.

Main Methods:

• Collection of individual animal fecal samples from ten VTEC O157 positive farms over 11 months.
• Monthly sampling of approximately 6266 samples from 1383 animals.
• Isolation and quantification of VTEC O157 from collected samples.

Main Results:

• VTEC O157 was isolated from 7.7% of samples and 28.9% of animals.
• Significant variation in shedding prevalence was observed across farms and over time.
• Ninety-two animals were positive on multiple occasions, with variable intervals between positive samples.

Conclusions:

• Individual animal shedding patterns of VTEC O157 are highly variable.
• The proportion of shedding animals and shedding frequency differ significantly between farms and over time.
• Inconsistent shedding patterns limit the effectiveness of targeted interventions for VTEC O157 control in cattle herds.