CHRONIC RESPIRATORY DISEASE/INFECTIOUS SINUSITIS

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Causative Agent(s)

Mycoplasma gallisepticum causing chronic respiratory disease in chickens and infectious sinusitis  in  turkeys.  This  is  the  most  pathogenic  of  all  avian  mycoplasmas.

Clinical Presentation and Epidemiology

From bird to bird (aerosol), on fomites and via eggs (vertical transmission). Once infected, birds remain carriers for life. Airsacculitis indicates a secondary infection (usually E. coli). Chickens – Inapparent infection or variable respiratory distress, rales, coughing, and sneezing. High morbidity, low mortality. Turkeys – More severe than in chickens. Nasal discharge with foaming of eye secretions. Swelling of paranasal sinuses is common. Airsacculitis may be seen. Decreased  weights  and  egg  production.  Encephalitic  form  has  been  reported.

Diagnostic Consideration

Enzyme Linked Immunosorbent Assay or rapid plate agglutination test (more sensitive) for screening. Tube hemagglutination inhibition test or culture techniques for confirmation. Polymerase Chain Reaction available.

Management and Treatment

Must consider secondary pathogens. Antibiotics in feed and water (start with parenteral in turkeys). Choice of drugs include chlortetracycline or oxytetracycline at 200g/ton of feed for

5 to 7 days, erythromycin (25mg/kg for 5 days), tiamulin 25-50mg/kg PO for 3-5 days, enrofloxacin 12.5mg/kg PO for 3-5 days. These may help with clinical signs, but do NOT cure infection. Tylosin has been injected subcutaneously at 1.3-2.2 mg/kg body weight or administered at 0.5-0.75 g/l drinking water for 3-5 days.

Bacterins are available which will prevent egg production losses, but not infection. Live vaccines are also available.