Risk factors associated with Mycobacterium avium subsp. paratuberculosis herd status in Québec dairy herds

Area of Science:

• Veterinary Medicine
• Animal Health
• Infectious Diseases

Background:

• Paratuberculosis, caused by Mycobacterium avium subsp. paratuberculosis (MAP), is a significant economic concern in ruminant farming.
• MAP's potential link to human Crohn's disease underscores the importance of its control.
• Effective paratuberculosis management focuses on limiting animal exposure to MAP, surpassing traditional testing and culling methods.

Purpose of the Study:

• To investigate the association between specific herd management practices and Mycobacterium avium subsp. paratuberculosis (MAP) status in dairy herds.
• To identify key risk factors influencing MAP prevalence within herds enrolled in a control program.

Main Methods:

• A retrospective case-control study design was employed, comparing MAP-positive (case) herds with MAP-negative (control) herds.
• Data were collected via a risk assessment questionnaire administered to herds in the Québec Voluntary Paratuberculosis Control Program.
• Mycobacterium avium subsp. paratuberculosis (MAP) was detected using liquid culture and the BACTEC 960 system, with multivariable logistic regression analyzing risk factors.

Main Results:

• Larger herd size was significantly associated with an increased risk of positive MAP herd status (OR=1.17).
• A higher proportion of purchased cows annually correlated strongly with positive MAP herd status (OR=5.44).
• These findings align with previous research identifying herd size and animal acquisition as critical risk factors.

Conclusions:

• Herd size and the proportion of purchased cows are significant management-related risk factors for Mycobacterium avium subsp. paratuberculosis (MAP) herd status.
• Preventing MAP introduction by managing new animal acquisitions and minimizing calf exposure to adult animals/feces are vital control strategies.
• Prioritizing biosecurity measures focused on animal introduction and calf management is essential for effective paratuberculosis control programs.