169. Mycoplasma diseases of swine

Question 1

Occurence and aetiology?

Answer 1

Enzootic pneumonia of Swine/Mycoplasma pneumonia of Swine

Occurrence: widespread, worldwide

• Mainly large scale farms
• great economic impact
• Poor growth rate,
• decr feed conversion (higher feed cost),
• predispose to 2dary

Aetiology: M. hyopneumoniae

• ONLY swine is susceptible (domestic and wild boars)
• virulence variants, surface proteins (adhesion, cytotoxic effect - damage respiratory epithelial)

Question 2

Epidemiology?

Answer 2

Epidemiology:

• Infection via aerogen (need close contact, especially in high density of animal),
• direct contact, tracheal discharge: respiratory infection
• Slow spread within the herd, frequently see consequences (poor weight gain) and not the direct CS
• High morbidity, low mortality
• Most frequent in growers between 3 and 6 months (maternal immunity in first 2 months oflife)
• Predisposing factors:
• Management:
• nutrition, overcrowding, stable, temperature, autumn, winter, humidity, NH3, mixing of
• animals, transporting to feeding unit
• infective agents: PRRS, circovirus, A. pleuropneumoniae, P. multocida, H. parasuis, B. bronchiseptica, Porcine respiratory disease complex (CRDC)
• losses are influenced by management

Question 3

Pathogenesis?

Answer 3

Pathogenesis:

• Aerosol infection Bacteria attach to the respiratory epithelium, alveoli (cytotoxic effect) damage of the epithelial cells( block cilia movement and then damage cilia)
• damage the alveolar macrophages, release of cytokines peribronchial infiltration(immune response) epithelial proliferation
• proliferation
• Immune suppression:
• secondary infections (A. pleuropneumoniae, H. parasuis, P. multocida, B. bronchiseptica, pyogenic bacteria)
• delayed immune response which help secondary infection
• Limited to the lungs (cannot enter blood, NO septicemia)

Question 4

Clinical signs?

Answer 4

Clinical signs:

• incubation 10-16 days
• Atypical, fever, anorexia, 1st sign - dry cough (increasing intensity)
• interstitial pneumonia (increasing, spontaneous), poor development, low weight gain
• secondary infections can complicate and modify clinical signs

Question 5

Pathology?

Answer 5

Pathology:

• Frequently seen in slaughterhouse
• Atelectasia in the anterior lobes (liver-like), interstitial pneumonia, peribronchial infiltration, pleuritis is absent (if see, then secondary infection),
• enlarged lymph nodes
• Histology: peribronchial, perivascular, interalveolar cell growth, lymphoid cells, histiocytes

Question 6

Diagnosis?

Answer 6

Diagnosis:

• Epidemiology - clinical signs - PM lesions
• Detection of agent: isolation (difficult, very slow, often overgrowth by other bacteria in respiratory tract), PCR, IF,
• ELISA (antigen detection)
• Detection of antibodies: ELISA, immunoblot, CFT, not usually used, wide infection at herd level, not reliable

Question 7

Treatment?

Answer 7

Treatment:

• Antibiotics (tiamulin, macrolides, lincomycin, fluoroquinolons, tetracyclines)
• Mass treatment in feed, water - regular treatment for 10-14 days (will not be allowed in the future)
• Remain carriers
• Improving management
• Prevention: general epidemiological rules

Question 8

Prevention?

Answer 8

Prevention: General epidemiological rules

• “all in all out” isolation of the different age groups
• Optimal nutrition and management
• Vaccines: inactivated vaccines, subunit vaccines - will prevent the severe form ofdisease
• Vaccination of piglets: from 1 week of age then 4 weeks later (in endemic), better at 6-8 weeks of age
• (after maternal immunity)
• Vaccination of pregnant sows: higher maternal protection
• Cannot prevent colonisation, only prevent clinical signs, efficacy can be diminished by
• immunosuppressive infection

Question 9

Eradication?

Answer 9

Eradication:

• 1) SPF (most reliable), retaining old sows in breeding, herd replacement
• 2) Generation shift (using antibiotics)
• Sows: treatment of sows before farrowing till weaning
• or sero-negative sows keep in breeding
• Early weaning
• Isolation of the piglets
• Control: bacteriological and serological examination, laboratory diagnostics of pneumonic diseases,
• slaughter house control

Question 10

Diseases caused by M. hyorhinis and M. hyosynoviae?

Answer 10

Diseases caused by M. hyorhinis and M. hyosynoviae

M. hyorhinis : lower economic impact than a)

• Widespread, present on the mucous membranes of healthy animals
• Mainly asymptomatic infection, sometimes bacteriaemia ʹ reach joints
• Clinical signs: 3-10 week old piglets (around weaning), slight fever, polyserositis, arthritis, restrictedmovement
• Pathology: inflammation of serous membrane (pericarditis, perihepatitis, etc)

M. hyosynoviae

• Carried in the upper respiratory tract
• 30-40 kg growers (fattening pigs, 3-4 months old)
• Septicaemia (slight fever), inflammation of joints - arthritis, bursitis, restricted movement
• Treatment