The coccus is .6 to .8μ in diameter, in short chains of 2 to 8 cells, or in some media much longer. Involution forms are common, and Norgaard claims to have seen indications of fission in two directions to form tetrads. The organism stains in the usual aniline dyes, as well as by Gram’s and Gram-Weigert’s method. It is nonmotile, ærobic, facultative anærobic, grows in solid and liquid media that is neutral, or slightly acid or alkaline (not if strongly acid), best at 98.6° F., and slower at the room temperature. In alkaline peptonized beef bouillon in 24 hours it forms threads and balls on the sides and bottom of the tube, leaving the liquid clear. On agar there are formed small shining, grayish colonies 1.5 mm. in diameter with brownish centre and bluish periphery. With all the sugars it produces acid, but no gas. It does not coagulate milk. On gelatine colonies are formed in four days, and there is no liquefaction.
History of the Outbreak. The outbreak commenced early in January, without any obvious occasion for the introduction of infection. There had been no chicken disease on the place for 25 years, and no chickens had been purchased except from a neighboring farm where the stock remained healthy. They had been fed on corn meal, wheat bran, wheat tailings and whole corn, together with scorched wheat from a burned barn. The poultry houses were clean and well aired, and after they had been closed there was no abatement of the disease. The water was from a stagnant pool receiving drainage from the stable, but this was no new condition and January is not the driest month with the foulest water. The suggestion may be hazarded that the infection may have been introduced by the usual infection bearer, the buzzard, or by some other wild bird, or mammal.
Pathogenesis. Among the chickens the most rapid and fatal cases were in pullets, then among the laying hens, while the capons and cockerels were less severely affected, and some survived from three to seven days.
Those inoculated intravenously as a rule sickened on the second or third day with a temperature of 110.7° F., and were found dead the following morning.
Some took injections of .25 to 1cc. in the pectoral muscles with impunity.
Chickens that had fasted 24 hours, took each daily for 3 days, a few cubes of bread soaked in a fresh bouillon culture. Death followed in four out of six, in from four to thirteen days from the beginning of the experiment. The birds gradually became listless, refused to eat, and remained quiet in a corner of the cage, with closed eyes and head drooping until it rested on the ground. Diarrhœa was frequent but not invariably present.
Chickens fed on the chopped up viscera of rabbits that had died of the disease perished in 3 to 10 days.
A white duck inoculated intravenously with .5cc. of peptonized beef bouillon culture, took ill on the 8th day, and died on the 12th. There was loss of coördination and use of the wings, temperature 109° F., and necropsy showed valvular endocarditis containing the streptococcus. A second duck sickened on the 11th day, but recovered after three days’ illness. Killed on 21st day, all cultures from heart, spleen and kidney remained sterile. Subcutaneous, intramuscular and feeding experiments failed to produce the disease in ducks.
A pigeon injected with .5cc. bouillon culture intravenously died on the fourth day with the internal lesions of chickens, and blood extravasations on head and neck. Intra-muscular injections and feeding experiments were fruitless.
In rabbits, intravenous injections of 1 to 1.5cc. led in 24 hours, to temperature of 105.3° F., without impairment of appetite, or other marked sign of illness, and as a rule the subject is found dead next morning. Intra-abdominal and intrapleural injections kill in two to four days, and subcutaneous ones in three days. In addition to the lesions found in chickens, there is often bloody urine, a sanguineous lymph on and beneath the cerebral meninges and in the fourth ventricle, and deep congestion of the cancellated tissue of the vertebræ. Streptococci are abundant in the lesions.