The Rickettsiae 



391 



for about a year with Rocky Mountain spotted fever and over a 

 year for t\phus. Vaccines for the prevention of other rickettsial 

 diseases are being investigated at the present time. 



Antibiotics have come to the rescue in man's fight against these 

 diseases. Terram\'cin is highly rickettsiostatic. In experimental 

 infections in chick embryos it appears to be one of the most effec- 



Fig. 70. Typhus vaccine. Formalin-killed preparation of epidemic 

 typhus rickettsiae from chick embryo yolk sac cultures. (Courtesy of 

 Lederle Laboratories Division, American Cyanamid Company, New 

 York.) 



tive antibiotics against the microbes of scrub typhus, Rocky Moun- 

 tain spotted fever, epidemic typhus, and rickettsialpox. Clinical 

 literature seems to bear out these experimental laboratory findings. 

 Aureomycin and Chloromycetin have also proven quite effective in 

 combatting some of these infections. 



By constant vigilance and by application of knowledge gained 

 in war and peace, diseases of rickettsial etiology can be effectively 

 controlled, and some of these scourges, second only to plague, 

 should become epidemics of the past. 



