Mario R. Castaneda

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Mexican typhus virus can be passed through ticks by the method of rectal injection. The virus will remain alive in the ticks for at least 12 days. These studies, together with one of our preceding publications and the work of Dyer, demonstrate that there are at least three insects-bedbugs, fleas and ticks-which must be considered as possibilities in(More)
In a preceding paper from this laboratory, Zinsser and Castaneda (1) reported upon the development of a method by which reliable agglutination reactions could be obtained, with Rickettsia suspensions, in sera from convalescent typhus patients and in those of convalescent or vaccinated animals. The experiments carried out by this method showed a definite(More)
The intradermal inoculation of Mexican typhus virus into immune guinea pigs produces a local reaction which is similar in its appearance to the lesion observed in the skin of normal animals submitted to the same treatment. The reaction in the immune animal appears earlier and fades sooner than the lesion in the normal guinea pig. The inoculation of(More)
1. The absorption of typhus sera (human or antityphus horse serum) with Proteus X-19 removes only the Proteus agglutinins, leaving the Rickettsia agglutinins intact. 2. The absorption of typhus sera with Mexican Rickettsiae removes the agglutinins for both the Rickettsia and Proteus X-19. 3. While normal or formalinized Rickettsiae are not agglutinated by(More)
The above experiments demonstrate that guinea pigs and rats subjected to vitamin-deficient diets to a point at which deficiency symptoms appear, and then inoculated with typhus virus, exhibit clinical pictures which indicate a far more severe infection than that observed in normal animals after inoculation. There is also a wider distribution of Rickettsiae(More)
1. Vaccines consisting of formalinized Rickettsiae of Mexican typhus fever, obtained by our X-ray rat method, produce definite resistance in guinea pigs to subsequent infection with the virus of this disease. 2. The resistance so produced amounts to complete immunity when the subsequent infectious dose is moderate-that is, consists of typhus blood or of(More)
1. The blood of guinea pigs convalescent from Old World and New World typhus infection develops agglutinating properties for the tunica and rat Rickettsiae of the New World diseases and for the louse Rickettsia of the Old World disease. 2. The two microorganisms are closely related, though probably not identical. 3. Human convalescents of both varieties of(More)
We have adduced evidence that guinea pigs can be completely or partially protected by three injections of typhus tunica material in which there are moderate numbers of Rickettsiae, treated for from 24 to 48 hours with a 0.2 per cent formalin solution. We believe that the immunization is due to the presence of the Rickettsiae, since in our preceding(More)