99. Blackleg.

Question 1

Occurence, aetiology?

Answer 1

Occurrence:

• endemic,
• ruminants (sometimes pigs and others),
• summer ʹ autumn (seasonality)

Aetiology:

• C. chauvoei
• Fastidious, present in the gut (gut soil cycle)
• Toxins: alpha (haemorrhagic necrotic toxin ʹ lethal toxin), beta, gamma, delta
• Active carbohydrate fermentation (produce large amount of acid +gas) = key factor!!

Question 2

Epidemiology?

Answer 2

Epidemiology

• Gut-soil, soil infection
• PO infection: spore
• Cattle: mainly endogenous (eat through soil) (cannot be connected to external predisposing effect),
• 2 months - 2 years old (not less than b/c maternal immunity, not older cause already met bact)
• Sheep: wound infection (shearing, mass treatment, iatrogenic)
• Other species rare

Question 3

Toxin effect?

Answer 3

Toxin effect:

• Alpha toxin gets into the blood & the brain
• responsible for the death of the animals

Question 4

Clinical signs?

Answer 4

Clinical signs

• Sudden onset;
• Incubation 1-3 days
• General: fever,
• depression,
• increased heart and breath rate
• Typical lesions in the muscles:
• oedema in large muscle masses,
• swelling
• painful, warm, crepitate;
• later painless, cold
• o In case of wound infection local lesions at place of entry
• o Movement problems, lameness

Question 5

Pm lesions?

Answer 5

PM lesions

• Lesions of suffocation (haemorrhages)
• Large muscles: oedema, gas,
• rancid smell (active fermentation of CH),
• muscles haemorrhagic,
• very dark b/c of the inhibited circulation

Question 6

Diagnosis?

Answer 6

Diagnosis

• Epidemiology
• clinical signs
• post mortem lesions
• Detection of the agent: Bacterium culture (p.m. C. septicum!),
• staining,
• IF (cannot differentiate from Cl. septicum),
• IHC,
• PCR
• (Cannot detect Abs)

Question 7

Differential diagnosis?

Answer 7

Differential diagnosis

(differentiate from all diseases where there is oedema formation):

1. malignant oedema,
2. purulent lesions,
3. abscesses,
4. anthrax,
5. pasteurellosis,
6. bluetongue

Question 8

Treatment?

Answer 8

Treatment

• Bovine: endogenous Æ Fast course: AB treatment is late
• Ovine: fresh wounds - wound toilette: surgery, disinfection (oxidative), Abs (penicillin)
• o Hyperimmune serum
• o Treatment of the herd (vaccine, antibiotics)

Question 9

Prevention, control?

Answer 9

Prevention, control

• Prevention of infection
• sterility,
• hygiene of farrowing,
• avoid wounds
• Vaccination
• Anaculture, anatoxin - polyvalent: 2-3 months, 2 vaccinations & yearly
• 10-12 months of protection