A disease of the mouth, fauces, nose and eyes, associated with the formation of false membranes, has been long recognized in birds (hens, ducks, pigeons, etc.), and is known to bird-fanciers by the names of roup, and diphtheria. The disease is characterized by the presence of a local inflammation in patches, associated in the early stages, with a free serous discharge, but, later, with the formation of white, or grayish, fibrinous exudate, which may be at first firm and smooth, later soft and cheese like, and still later in many cases more or less necrotic and sloughing. In Dr. Moore’s experience this is more common on the conjunctiva than on the nares or fauces. The interior of the eye was not involved in the inflammation. Beneath the false membrane the mucosa was devoid of epithelium and the underlying tissue was red, raw and angry, bleeding readily when handled, and infiltrated with an excess of lymphoid cells.
The lesions however were by no means constant. In some even of the fatal cases, the exudate was merely muco-purulent, while in others the false membrane was quite abundant.
The gravity of the affection also varies in different outbreaks or in the same outbreak at different times. Sometimes it runs a very rapid and fatal course, while at others it becomes chronic and comparatively dormant and the great majority recover.
In its more virulent form it is readily inoculable on birds, mice, rats, and rabbits, while the milder cases are not easily propagated in this way.
The false membrane contains a variety of saprophytes, and among them the pathogenic bacillus, which may be obtained in pure culture by inoculating it on a rabbit or mouse. Emmerich believed this bacillus to be identical with the Klebs-Löffler bacillus of diphtheria in man, but Löffler recognizes it as essentially distinct.
The bacillus diphtheriæ avium is 0.8 to 1.5μ long, by 0.8 to 1.2μ broad. The ends are oval so that short specimens seem round. In bouillon cultures they form chains or clumps. They stain in aniline dyes, most deeply at the poles. Are not stained by Gram’s method. They are non-motile, ærobic, grow in agar, and alkaline bouillon, but render the latter acid in one or two days. Do not grow on peptone gelatine, nor produce gas with sugars. Are killed in 5 minutes at 58° C. (137° F.). Are killed by dryness in 24 hours, by sulphuric acid (0.25 ∶ 100) in 10 minutes, by lime water in 1 minute, and by sulphur fumes.
Pathogenesis. Eight rabbits inoculated subcutaneously with 0.1 cc. of the bouillon culture died in 18 to 36 hours. Of several white and gray mice inoculated only one died. Inoculations of mature hens subcutem and on the nose had no effect. Inoculation of a six weeks old chicken caused death in 4 days with bacilli in the liver and blood (Moore). Inoculation of pigeons produced the disease (Löffler). It seems doubtful whether the milder forms part with their virulence to birds, when cultivated artificially, or whether a special susceptibility is required in order to render the inoculation effective.
Prevention. Besides the general conditions of good hygiene, cleanliness, pure air, and pure water, the strict exclusion of the germ is the great desideratum. New fowls should not be taken into a flock, when they show any indication of disease in the mouth, throat, nose or eyes, nor when they come from a flock in which such signs of disease can be found. When examination of the flock, from which they are sold, cannot be made, the new fowls should be placed by themselves in quarantine until proved sound. Sound flocks should not be allowed to wander at large and mingle with the birds that are unsound, or open to suspicion. Neither should they be allowed to come in contact with manure from suspected poultry yards. If disease of air passages, mouth or eyes appears, separate at once the diseased fowl, and sprinkle roost, house and yard with dilute sulphuric acid, quicklime, or other disinfectant.
Treatment. Beside separation and disinfection the local use of antiseptics to the surface divested of the false membrane gives the best promise. Boric acid solution (4 ∶ 100) or sublimate solution (1 ∶ 5000) may be applied to the eye. For the nose and mouth somewhat stronger applications may be made.
Prevention of infection to man. The essential difference of the Klebs-Löffler bacillus of diphtheria in man, and the microbe of this affection in fowls does not exclude the necessity of avoiding contagion from birds to man. Among reported cases of such infection are: (1) That at Wesselhausen, where 4 attendants on the fowls contracted the disease from the sick fowls at a time when no other cases existed in the human population: (2) That of Sebdon where 6 persons suffered and 10 fowls fed by a hospital attendant also suffered: (3) That of Tunnis in which diphtheria prevailed in fowls, and soon also in those who fed them producing an extended epidemic: (4) That of Jacksonville, Ill., where a diphtheritic chicken, conveyed the disease, with fatal effect, to a child which fondled it (Moore).