Abstract
The following observations have been made in the course of preliminary studies with 48 cultures of the brucella group on 74 rhesus and 14 cynomolgus monkeys:
A single oral administration of 21 different Br. abortus strains produced in 24 Macacus rhesus and 1 M. cynomolgus monkeys nonfebrile infections, followed by the formation of specific agglutinins of moderately high value. The dosage varied from 7 to 400 million and in some experiments it consisted of many billions. The strains identified serologically as abortus or para-abortus varieties and in the dye test as “bovis” or “melitensis” types had been isolated from bovine pathological specimens in the United States, Germany, Hungary, Italy and Switzerland.
Blood cultures have not been successful. The value of the serum agglutinins and their persistence depends on the feeding dose. Rapid disappearance of the agglutinative power to a low titer or to the zero point is worthy of note. A cutaneous application of approximately 20,000 bacteria has induced an infection. The incubation period as indicated by the appearance of the serum reaction varied from 9 to 30 days and is influenced by the infective dose.
The absolute evidence of infection has been secured through the recovery of the organisms from the tissues of 4 monkeys which have been sacrificed on the 34th to 52nd day. Three animals killed on the 43rd, 56th, 199th day furnished sterile cultures. Probably every Br. abortus strain when fed in sufficiently large dosage is pathogenic provided susceptible monkeys are used.
By feeding 100 million Br. abortus type “suis” of bovine, but in all probability of porcine origin which has retained its characteristics through the passage, a febrile disease with anatomical lesions indistinguishable from those of a Br. melitensis infection has been produced.
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