Mycoplasma-Related Diseases

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Name of the mycoplasma Name of the disease Signs and lesions Diagnosis and comments
Mycoplasmal (Enzootic) Pneumonia Age: 6 weeks to market age (especially 2-4 month old pigs)
Clinical: persistent, dry cough and dyspnea with flare-ups of pneumonia. Good appetites but unthrifty.
Lesions: Cranioventral lobules of clearly demarcated gray consolidation, mucopurulent exudate in airways. Morbidity variable/mortality low. Histologically there is marked lymphoid hyperplasia around airways.
Often diagnosed on the basis of signs, lung lesions at necropsy and slaughter. IFAT of lung lesions may reveal mycoplasmas. Difficult to culture. Serology (CF, ELISA, and IHA) is sometimes used for herd diagnosis. Improved housing and ventilation with reduced stocking density help in control.

Mycoplasma hyorhinis

This organism can be found in association with various lesions in swine but a primary role in
disease is unclear.

Mycoplasmal Polyserositis
and Arthritis
Age: Usually in 3-10 week old pigs but sometimes in young adults. 
Clinical: Acutely affected pigs visibly ill and with fever. Abdominal tenderness with preference for sternal recumbency.
Lesions: Serofibrinous pericarditis, pleuritis and peritonitis. Later there may be fibrous adhesions. Arthritis often severe in one or more joints; later, villous hyperplasia, possibly pannus.
Isolation of the organism from acute cases. Morbidity 20 to 35% but mortality low. Infection may persist in joints but many lame pigs slowly recover with internal adhesion and poor gains. Differentiate from Haemophilus parasuis andStreptococcus suis.**
Mycoplasma hyosynoviae Mycoplasmal Arthritis Age: In pigs 12-24 weeks old.
Clinical: Lameness, difficulty in arising, kneeling in some. Often in straight legged, muscular pigs with hidden joint swellings. Serofibrinous exudate with synovial membranes swollen.
History, signs and lesions are suggestive. May respond well to lincomycin, tylosin, or tetracycline injection. Isolate organism from acutely infected joints. Differentiate from Haemophilus parasuis andStrep. suis, erysipelas.**

CF - complement fixation
ELISA - enzyme-linked immunosorbent assay
FA - fluorescent antibody
IFAT - immunofluorescent antibody test

IHA - indirect hemagglutination
* Many other mycoplasmas have been isolated from swine but these three are the only ones clearly identified with disease.
** Haemophilus parasuis and Streptococcus suis cases often have arthritis and/or synovitis and a fibrinous meningitis.

Meningitis usually is absent in the mycoplasmoses