Riemerella Pasteurella Infection

Infection with Riemerella (Pasteurella) Pasteurella is a contagious, widely distributed disease that primarily affects young ducks and turkeys. Other waterfowl, chickens, and pheasants also may be affected. The epidemiology and pathogenesis are not understood. Ducks are believed to be infected when Pasteurella is introduced into toenail scratches of the webbed foot. Turkeys may be infected by injuries or by the respiratory route when another pathogen disrupts the respiratory epithelium.

Affected ducks, usually 2-7 wk old, often have ocular and nasal discharges, mild coughing and sneezing, tremors of the head and neck, and incoordination. Stunting may occur. Fibrinous exudate in the pericardial cavity and over the surface of the liver is the most characteristic lesion. Fibrinous airsacculitis is common, and infection of the CNS can result in fibrinous meningitis. The spleen and liver may be swollen. Pneumonia may be seen. Mortality is usually 2-30%.

Affected turkeys, usually 5-15 wk old, often exhibit dyspnea, droopiness, hunched back, lameness, and a twisted neck. Fibrinous pericarditis and epicarditis are the most pronounced lesions. There may also be fibrinous perihepatitis, airsacculitis, and purulent synovitis. Osteomyelitis, meningitis, and focal pneumonia are seen occasionally. Mortality is 5-60% and condemnations 3-13%.

Diagnosis is based on signs, lesions, and isolation and identification of the causative organism, because other diseases, particularly colibacillosis and chlamydiosis, may produce similar lesions. Chocolate agar medium is recommended for isolation, although blood agar is also used, with incubation at 37°C in a candle jar or under 5% carbon dioxide. The isolate should be serotyped because the information may be needed for vaccine selection and epidemiology. Biochemical characteristics can be used to differentiate this organism from other bacteria that cause important diseases of ducks and turkeys, particularly Escherichia coli and Pasteurella multocida . Impression smears help to determine whether chlamydia is involved.

Careful management practices are important for prevention of infection. Rigid sanitation and depopulation are necessary for elimination of the disease. A bacterin and, more recently, a live vaccine, which include the three most common immunotypes of R Pasteurella , are available for use in ducks. An autogenous oil-emulsion bacterin can be used in turkeys. A combination of penicillin and streptomycin, or sulfaquinoxaline can be used for initial treatment, but an antibiotic sensitivity test should be performed.