109. Streptococcosis of swine.

Question 1

Streptococcoses Aetiology?

Answer 1

Streptococcoses

Aetiology:

• Pyogenic Streptococcus-species
• Gram +ve cocci, chains; Haemolysis (alpha, beta)
• Lancefield-antigens (no connection btwn immunity & atgs – but can be used in diagnostic work)
• Virulence factors – responsible for different kinds of diseases:
• capsule (protection of bacteria from phagocytosis),
• surface proteins (attachment, protective effect),
• EC enzymes (causing lesions – produce less EC enzymes than staph.)
• Resistance: medium (not resistant against disinfectants/heat treatment; can be protected from dehydration & can survive in the environment)
• Related genera: (both don’t belong to streptococcus genus anymore)
• Enterococcus (saprophytes – in immunosuppressed individuals) – can produce probiotics that have
• antibacterial effects
• Lactococcus (used in dairy industry)
• (Streptococci can be found on the MM)

Question 2

Clinical forms, Clinical signs of Streptococcosis?

Answer 2

Clinical signs, clinical forms

• Local: dermatitis, MM, cellulitis; arthritis; mastitis, metritis; abscesses
• Generalised:
• Swine: streptococcosis
• Horse: strangles
• Calf: S. pneumoniae - bronchopneumonia (can cause disease in humans as well)
• Pigeon: S. bovis - septicaemia (can cause mastitis in cows)

Question 3

Swine streptococcosis Occurence and aetiology?

Answer 3

Swine streptococcosis

• Occurrence: widespread

• Aetiology:

• S. suis (Lancefield D group): 35 serotypes (polysaccharide capsule – differentiate serotypes →connection with immunity)
• Virulence factors (capsule, haemolysin, surface proteins)
• Virulence variants (virulence factors occur in different strains in different amounts)
• S. porcinus (Lancefield E, P, U, V) – cause local lesions in growers & fatteners (freq don’t see clinical signs)
• S. dysgalactiae, S. equi subsp. equisimilis (lower importance)

Question 4

Epidemiology of swine streptococcosis?

Answer 4

Epidemiology:

• Clinical forms: Local; Generalised: 1-5 week old piglets, sometimes older (just after weaning)
• Source of infection: litter mates, sows (udder, milk, discharges), environment
• S. porcinus mainly in growers and fattening pigs
• Predisposing effects: overcrowding, iron deficiency, infections (PRRS, circovirus = immunosuppressive)

Question 5

Pathogenesis of swine streptococcosis?

Answer 5

Pathogenesis

• Infection: wound, per os, aerogen
• Development of the disease is influenced by:
• Resistance of the pig / virulence of the strain:
• asymptomatic - local purulent lesions - septicaemia

Question 6

Clinical signs of Swine streptococcosis?

Answer 6

Clinical signs:

• Local:
• swollen joints,
• limping;
• abscessation of LNs
• Generalised:
• anorexia,
• fever (>40oC);
• neurological signs –
• purulent meningitis,
• hyperaesthesia;
• endocarditis,
• peritonitis,
• abortion;
• unwillingness to stand

Question 7

PM lesions of swine streptococcosis?

Answer 7

PM lesions:

• anaemia (due to iron deficiency),
• haemorrhages;
• spleen is rubber-like & enlarged;
• abscesses in the liver;
• purulent arthritis,
• purulent meningo-encephalitis;
• enlarged LNs

Question 8

Diagnosis of Swine streptococcosis?

Answer 8

Diagnosis

• Epidemiology – clinical signs (especially CNS) – PM lesions
• Detection of the agent: bacterium isolation
• Detection of antibodies: ELISA (detecting infection & not the disease)

Question 9

Treatment and prevention of Swine streptococcosis?

Answer 9

Treatment, prevention

• Narrow spectrum AB:
• Penicillin, erythromycin, tetracycline: Individual and mass treatment;
• Bacterium carriage remains (bacteria remain on the MM)
• If resistance: Macrolides
• Avoiding predisposing effects: provide iron, reduce overcrowding etc.
• Vaccine (S. suis): only serotype specific protection (35 serotypes) –
• no cross protection so vaccination is limited