Topic 105 - Paratuberculosis (RED) Flashcards
What is paratuberculosis?
a chronic enteritis affecting mainly cattle, sheep and goats
Another name for paratuberculosis
Johnes disease
Occurrence for paratuberculosis
Worldwide, very frequent in large scale farms
Host susceptible for paratuberculosis
Most susceptible is the cattle, but also sheep and goat are main hosts
Causative agent for paratuberculosis
M. avium subspecies paratuberculosis
Incubation time of paratuberculosis
long
8-12 weeks
Over 9 months of incubation before clinical signs appear
How is paratuberculosis shed?
Faeces ⭢ Start shedding before clinical signs
Milk
!! They shed lifelong !!
Age susceptible for infection of paratuberculosis
Every age is susceptible, but depending on when they get infected they show clinical sign or have asymptomatic shedding
1. Infection before 6 months of age = Clinical signs appear later
2. Infection after 6 months of age = asymptomatic and sheds the bacteria
At which age does the clinical signs appear in case of paratuberculosis?
at 2-5 years of age, typically appear after 2nd or 3rd calving
The clinical signs appear after predisposing factors
Clinical signs in sheep and goats are less frequent
Predisposing factors for clinical signs of paratuberculosis to appear:
Pregnancy
Parasite infection
Immunosuppression
Route of infection in case of paratuberculosis
Per os
Pathogenesis of paratuberculosis
1. Infection per os
2. Bacteria reaches the gut, and there is a replication intra cellularly in T-lymphocytes and macrophages
3. There is a lysis of macrophages and released bacteria are phagocytes by macrophages causing a cytokine production of T-lymphocytes and there is a cellular infiltration in the gut wall
4. As a result, the gut wall till be thicker, causing decreased absorption and protein loss through the lumen of the microvilli and appear in the gut
5. There will be a diarrhoea with a terrible smell and weight loss, causing a drop in milk production.
Clinical signs in case of paratuberculosis
Weight loss
Decreased milk yield
Severe diarrhoea: Watery, smelly and painful
The diarrhoea is squirting out, like jet
Post mortem lesions in case of paratuberculosis
Sheep and goats will have milder lesions, but the lesions are quite severe in cattle
1. Wall of small intestines are thickened
2. Transverse folds
3. Enlargement of lymph nodes
Diagnostic methods for paratuberculosis
With epidemiological data, clinical signs and PM lesions, we can have a good diagnosis
- Ziehl Neelsen staining is enough to diagnose
- PCR is used
- Allergy testing is used: Johnin/paratuberculin and avian tuberculin
Treatment methods for paratuberculosis
NO TREATMENT !!
Prevention methods in case of the disease, paratuberculosis
Movement restrictions !!
- Infected animals may only be transported to slaughter
- Disinfection
- Not using infected pastures for a year
Prevention methods in order to decrease the spread of paratuberculosis within the herd
- Isolation of sick animals
- Good hygiene
- Clean water
- Diseased animals should be culled
Vaccination in case of paratuberculosis
!! gives cross reaction with M. bovis, a vaccine can only be used with permission from the authority in countries free from tuberculosis and in closed herds !!
Use live and inactivated vaccine, they are quite effective
How to eradicate paratuberculosis
- Test and slaughter ⭢ Not feasible, very difficult
- Generation shit ⭢ carefull of re-infections !! We separate the calves after birth
- Herd replacement
Definition of disease free herd in case of paratuberculosis
- There are no clinical signs of the disease
- Laboratory examinations are negative
- There are no lesions in slaughtered animals
