Immunological Relationship Between Spotted Fever and Exanthematic Typhus

Summary and Conclusions The inoculation of a highly virulent strain of spotted fever virus into guinea-pigs recovered from typhus infection has shown that these animals are highly resistant to the new infection. There is a very low mortality rate as compared with normal animals and the duration of the febrile reaction is shorter. The transfer of the virus through a series of typhus-immune guinea-pigs shows a further decrease in activity for these animals, while the virus retains its virulence for normals. Whether the typhus infection is orchitic or non-orchitic, including the typical Old World “Breinl” strain, seems to make no difference in the resistance to the spotted fever infection. Cross-reactions with the technic of agglutination and of complement fixation are reported with spotted fever immune sera and typhus rickettsiae. From the experimental data presented we conclude that there is a definite immunological overlapping between spotted fever and typhus infection.