136. Haemorrhagic septicaemia of cattle.

Question 1

Occurence and Aetiology of Haemorrhagic septicaemia of cattle?

Answer 1

Occurrence:

• Tropical & subtropical areas – India, Sri-Lanka, SE-Asia, Africa, other sporadic (Europe, US)

Aetiology:

• P. multocida B:2 (Asia), E:2 (Africa), other
• • (B & E = capsule type, 2 = cell wall type)
• • Capsule – protects the bacterium → causing septicaemia

Question 2

Epidemiology of Haemorrhagic septicaemia of cattle?

Answer 2

Epidemiology

• Hosts: cattle, buffalo, ruminants, sometimes other (horse, donkey, pig)
• Predisposing factors (accumulation of factors needed): monsoon, exhausting work
• In endemic areas: ½-2 year old animals (maternal Abs to younger than 1/2y & >2y have active immune

protection)

• High morbidity, high mortality – in non-endemic regions (close to 100%)
• Reconvalescent animals from previous outbreak: carrier animals

Question 3

Pathogenesis?

Answer 3

Pathogenesis

• Source of infection: carrier animals (discharge)
• Infection: aerogenic (p.o.) infection, close contact is needed
• Colonisation in MM of upper resp. tract
• Asymptomatic carriage lasts until presence of predisposing effects
• Bacterium propagation in the tonsils → lymph & BVs → blood
• Septicaemia, endotoxin effect (responsible for clinical signs)

o Coagulopathy, damage of the endothelial cells

o Cell wall protects the bacterium in the blood, when the bacterium dies the endotoxin (LPS) is

released

• Can colonise the lungs & cause pneumonia
• 8-24 hours death (acute)
• Protection: humoral (Igs)

Question 4

Clinical signs?

Answer 4

Clinical signs

• Forms: peracute, acute, subacute

• Fever,
• depression,
• anorexia,
• serous nasal discharge,
• salivation, oedema (larynx – harsh voice, head),
• dyspnoea (neck stretched, open mouth breathing),
• listlessness,
• diarrhoea,
• pneumonia

Question 5

Pathology?

Answer 5

Pathology

• Peracute often don’t see any pathological signs
• more seen in acute & subacute/chronic
• Peracute:
• haemorrhages,
• serous fluid in the body cavities,
• SC oedema (yellow, gel-like),
• enlarged LNs
• Subacute:
• haemorrhagic
• gastroenteritis,
• fibrinous pleuropneumonia (not extended!)

Question 6

Diagnosis?

Answer 6

Diagnosis

• Epidemiology – clinical signs – lesions
• Detection of the agent: bacterium isolation, identification (blood, organs), PCR (serotyping)
• Detection of antibodies (when disease is not v fast): ELISA, immunoblot

Question 7

Treatment?

Answer 7

Treatment

• Bad outcome when you already see the clinical signs
• Treatment used in case of contact animals
• Early antibiotic treatment: Penicillin, tetracyclines, macrolides, potentiated sulphonamides
• Rest

Question 8

Prevention?

Answer 8

Prevention

• Avoiding predisposing factors (however cannot influence monsoon)
• Vaccine: inactivated (oil/alugel, 6-12 months protection), attenuated

o Giving 2 vaccines – year long protection