Occurrence of Infectious Myxomatosis in Southern California.

Abstract

During the summer of 1930 twelve reports from rabbitries in the regions of Santa Barbara, Ventura, and San Diego were made of a disease presenting the following symptoms. The rabbits were acutely ill and exhibited, as a rule, an oedematous condition in the regions of the nose and lips, the external genitalia and a conjunctivitis. A purulent discharge occurred from the eyes and nose. The ears also became greatly thickened and drooped as a rule. Animals that lived longer than a week or 10 days after the appearance of symptoms often developed nodules around the nose, eyes, or on the ears. Upon autopsy, the lymph nodes and spleen were found usually to be enlarged. The nodules and oedematous areas were found to contain a gelatinous material.

The disease was transmitted with facility by rubbing the discharge from the eyes and nose, or the extract from tissues, into the skin, or by injecting the same. Comparison of the above findings with reports of Hobbs, 1 Rivers 2 and others who have studied infectious myxomatosis produced by the South American virus shows striking similarities, the chief difference being that the disease encountered in California is not transmitted with as great ease by contact among experimental animals as is the South American disease. First attempts to transmit the disease by filtrates passed through medium Berkefeld filters were negative, but later attempts with coarser filters were positive.

Dr. Rivers has exchanged histopathological slides and virus and after studying our slides states: “From your sections there is good reason to suppose that the disease you are working with is the so-called infectious myxomatosis of rabbits.”

Certain comparative experiments of the California strain with the South American strain provided by Dr. Rivers are recorded in Table I.