Johnes

What is the pathogen responsible for Johne's disease?

Mycobacterium avium subsp. paratuberculosis

At what age are young calves most susceptible to Johne's disease?

Pre-weaning stage.

What are the stages of infection in Johne's disease?

Initial infection, carriage, sub-clinical, and clinical.

What is a common clinical sign of Johne's disease?

Bubbly diarrhea, weight loss, reduced production.

How can Johne's disease be transmitted?

Through colostrum/milk, feces from infected cattle, environmental spread, and wildlife.

What type of immune response is initially mounted against Johne's disease?

Cell mediated immunity.

What is the prognosis for clinical cases of Johne's disease?

Poor prognosis; animal may need to be culled or bred to beef stock.

What is one method to test for Mycobacterium avium subsp. paratuberculosis in feces?

PCR of pooled samples.

What is the sensitivity of antibody detection (ELISA) for Johne's disease?

Higher sensitivity but lower specificity.

What is a sign that Johne's disease may be progressing?

Increased bacterial shedding in feces.

What should be done with colostrum from positive cases of Johne's disease?

It should not be pooled and should be tested for quality.

What age do clinical signs of Johne's disease typically develop?

Between 2 to 6 years.

What is a critical management strategy for preventing Johne's disease?

Maintain a closed herd.

What is a recommended practice for calf management in relation to Johne's disease?

Snatch calving and minimize exposure to infection sources.

What are the risks associated with breeding from Johne's disease positive animals?

Increased risk of spreading the disease within the herd.

What should be a crucial part of farm management to control Johne's disease?

Regular bulk milk antibiotic testing.

How can fomite spread be minimized on a farm?

By practicing border biosecurity and using clean PPE.

What clinical sign may indicate the presence of edema in Johne's disease?

Bottle jaw or brisket edema.

How can the presence of bacteria or immune response be detected in Johne's disease?

Through fecal testing and serology.

What is a common environmental source of Johne's disease?

Feces from infected livestock.

What should be regularly cleaned to help control Johne's disease?

Calving areas.

What type of vaccination is mentioned in relation to Johne's disease management?

Firebreak vaccination.

What is a recommended practice for youngstock management in relation to Johne's disease?

Minimize exposure to potential infection sources.

What is one consequence of an increased incidence rate of scour related to Johne's disease?

Higher likelihood of introducing infected animals.

How does the immune response change over time in Johne's disease?

It decreases, allowing bacteria to proliferate.

What is a characteristic change in blood tests for animals with Johne's disease?

Low albumin and normal globulin levels.

What is the role of environmental persistence in the spread of Johne's disease?

It allows the pathogen to survive and be transmitted.

How should farms implement a national Johne's management plan?

Through improved management, biosecurity, and strategic testing.

What is a potential source of Johne's disease from wildlife?

Deer and rabbits.

What should animals showing clinical signs of Johne's disease be subjected to?

Cull or breed to beef stock.

What is the term for when calves are removed from their dam to control Johne's disease?

Snatch calving.