Abstract
Following the method of Goodpasture, Zia 1 cultivated successfully typhus Rickettsia of endemic and epidemic types in the chorioallantoic membrane of developing chick embryo. This was confirmed by Wenckebach 2 with endemic typhus, Bengtson and Dyer 3 with Rocky Mountain spotted fever, and Cox 4 with endemic typhus fever and Rocky Mountain spotted fever. These authors made a special study of the distribution of the Rickettsia in the infected embryo and found that whole embryo, brain, liver, chorioallantoic membrane, and yolk sac were infectious for guinea pigs, thus proving the presence of Rickettsial bodies. On the other hand Bengtson was not able to demonstrate any Rickettsia by direct smear in any of the organs. In view of the fact that various viruses have a different distribution in the fertilized egg, it was considered of interest to study the distribution of Rickettsia of the murine typhus fever by cultural methods. The procedure employed was as follows:
Growth of murine typhus Rickettsia in Maitland culture was inoculated on to the chorioallantoic membrane of fertilized eggs 10–12 days old. They were incubated at 34°C for 8–9 days after which the eggs were opened, and the membrane, liver, spleen, stomach, intestine, brain, lungs, heart, and kidney were aseptically removed and inoculated separately on to Zinsser's “tissue-agar” media 5 and Maitland flasks. Direct smear of all tissues were negative except for a few organisms occasionally found in smears made from the membranes. The cultures were examined after 12–20 days of incubation, and Macchiavello's technic of staining was employed for demonstration of Rickettsia. Sections of brain, liver, and spleen were made and stained with eosin and hematoxylin.
Result: It was found that about 80% of the 48 eggs so inoculated showed dead embryos on examination, of which approximately 10% was found to have died of bacterial contamination.
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