172. Diseases of pigs and sheep caused by haemotropic mycoplasmae.

Question 1

Swine M.suis occurence ethiology and epidemiology?

Answer 1

Icteroanaemia of swine caused by M. suis

Occurrence:

• sporadic,
• worldwide

Etiology:

• Mycoplasma suis (Eperythrozoon suis),
• species specific,
• cannot be cultured,
• replication on red blood cells

Epidemiology:

• Transmission:
• blood sucking parasites (mechanical vectors - lice), surgery (iatrogenic),
• cannibalism
• (fresh blood in contact), intrauterine infection can occur,
• discharges

Question 2

Epidemiology of swine M.suis?

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 of life)
• 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 of M.suis?

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 proliferation -> peribronchial infiltration(immune response)-> epithelial 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 of M.suis?

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 of M.suis?

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 of M.suis?

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 of M.suis?

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

Question 8

Prevention of M.suis?

Answer 8

Prevention: general epidemiological rules

• ͞”all in or all out” isolation of different age groups
• Optimal nutrition and management
• Vaccines: inactivated vaccines, subunit vaccines - will prevent the severe form of disease
• 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 of M .suis ?

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: reach joints
• Clinical signs:
• 3-10 week old piglets (around weaning),
• slight fever, polyserositis, arthritis, restricted movement
• 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