J. F. SULLIVAN AND CLARENCE H. THOMPSON, JR.
TURKEYS, like chickens, are subject to a respiratory disease that has a chronic course.
The name "infectious sinusitis" (IS) has been suggested to differentiate it from a similar appearing ailment caused by a deficiency of vitamin A.
The term "swellhead" is used commonly to describe the characteristic appearance of infected birds once the sinuses have become distended with exudate.
The name "air-sac infection" is applied to this disease when the symptoms and lesions are confined to the lower part of the respiratory tract.
In a study conducted by the National Poultry Improvement Plan in 1953, "sinusitis" was cited as one of the four most important diseases of turkeys in 11 of the 19 leading turkey-raising States. It is serious because affected turkeys lose appetite and weight and treatment takes time and money.
The agent that causes IS in turkeys is a pleuropneumonialike organism, which cannot be distinguished from the agent that causes chronic respiratory disease (CRD) in chickens. Agents recovered from either chickens or turkeys, when injected into susceptible birds in the laboratory, produce characteristic symptoms and changes in tissues.
IS is contagious a point that distinguishes it from deficiency of vitamin A. IS may be spread by direct contact or indirectly in contaminated air and dust. The causative agent has been isolated from eggs laid during certain stages of the disease. That fact strongly suggests that transmission through eggs and incubation has some part in the general spread of the disease.
The first symptoms may be overlooked or discounted as being unimportant. Birds at first shake their heads in an effort to dislodge the discharge that accumulates in the nasal passages. The discharge often can be seen on the feathers of the wings. Foamy secretions appear later in the eyes. A noticeable swelling of the sinuses follows.
These symptoms, unchecked, may culminate in impaired vision, inability to find food, and rapid loss of weight.
In some cases the main lesions are confined to the lower part of the respiratory tract, where they cause the development of generalized symptoms of respiratory distress (air sac infection).
The primary lesions usually are confined to the sinuses and their lining membranes. The excessive amount of exudate resulting from the inflammation of these membranes causes the sinuses to dilate until they produce a visible swelling of the face. The consistency of the discharge is variable. It is watery in the early stages and becomes progressively thicker as the infection continues. In a few advanced cases the material is cheesy.
In outbreaks where the lesions are confined to the air sacs and lower parts of the respiratory tract, the findings at autopsy are like those noted in CRD infections in chickens.
The symptoms and lesions observed in infected poults are characteristic and furnish ample evidence to justify a presumptive diagnosis of infectious sinusitis. Confirmation of a diagnosis of this type may be established in the laboratory by bird or egg inoculation techniques, or by isolation and identification of the causal agent of the disease in enriched bacteriological media.
Antibiotics, including streptomycin, Aureomycin, and Chloromycetin, have been used to treat infectious sinusitis of turkeys with varying degrees of success. These drugs may be mixed in the feed, injected directly into the affected sinus, or, in the lower respiratory form of the disease, administered intramuscularly. The intramuscular methods, which assure each bird an adequate therapeutic dose, seem to be best.
PROGRAMS designed to prevent the spread of infectious sinusitis to clean areas and flocks serve as one of the chief means of combating the disease. Poults should be obtained from a reliable hatchery where healthy breeder flocks are maintained under adequate supervision. Eggs from flocks showing any active respiratory infection should not be set. Breeder flock replacements should never be obtained from an unknown source or from a flock with a recent history of respiratory disease, because of the danger of obtaining apparently healthy carriers.
Infectious sinusitis can be eradicated by marketing the entire flock. If flock conditions are such that a less severe method is desired, the flock should be isolated, and all birds known to be infected should be removed. Infected birds may be identified by physical examination.
It is generally advisable to market the rest of the flock as early as possible.
J. F. SULLIVAN is a veterinarian employed by the Animal Disease and Parasite Research Branch of the Agricultural Research Service.
CLARENCE H. THOMPSON, JR., is a veterinarian employed by the State Experiment Stations Division of the Agricultural Research Service. He has degrees from Kansas State College. Dr. Thompson was formerly with the Animal Disease and Parasite Research Branch.