MEDICAL SOCIETY DISCOVERY

The mode of infection of Infantile Paralysis has been discovered by officers of the Bussey Institute and of the Medical School working in collaboration with the Massachusetts State Board of Health. It has been found that the ordinary stable fly or Stomoxys Calcitrans transmits the virus of the disease. The discovery is a brilliant example of modern experimentation.

The well-established fact that diseases have been carried by insects led the State Board of Health, of which Dr. Henry P. Walcott '58, of the Corporation, is chairman and Dr. Mark W. Richardson '89 is secretary, to start a through investigation of the disease along those lines in the summer of 1911. Mr. C. T. Brues, instructor in economic entomology in the Bussey Institute, and Dr. Philip A. E. Sheppard, M.D. '10, took charge of the research. They sought to find insects whose habits fitted in with the occurrence of the disease both as to place and time. After eliminating all non-migratory insects and all whose bite would have attracted particular attention, they finally concluded that the stable fly was the only insect whose habits could be made to account for the scattered infection of Infantile Palalysis and for its occurrence only in the late summer and early autumn.

The next step was to see by experiment whether the stable fly could carry the virus. The investigation was transferred to the Medical School, where it proceeded under the charge of Professor M. J. Rosenau. Working with Mr. Brues, he infected monkeys with the disease by injection, and then allowed them to be bitten by the stable flies. These flies then bit other monkeys, and after various difficulties, it was found that in six cases out of twelve the animals were infected. The principle was now confirmed by further experimentation at Washington and the proof that the fly carries the virus was made complete.

The adult stable fly feeds exclusively on the blood of animals, and less commonly on human beings. They do not enter houses and are inactive in rainy weather. The control of the insect will probably prove very difficult, and its eradication impossible, but methods will surely be developed to reduce the number of its breeding places and to decrease its danger to human beings.