696 TYPHUS FEVEK 



agreement that ordinary cultural methods applied to typhus blood 

 yield no result, but lately some attention has been attracted 

 to the isolation by Plotz of a gram-positive anaerobic bacillus 

 (b. typhi exanthematici) which Olitzky and others have also 

 cultivated from infected lice. Further, a proteus-like bacillus 

 has been isolated from the urine in typhus fever, and though 

 there is no evidence that this organism has any causal relation- 

 ship to the disease, several observers have confirmed the 

 observation that it is agglutinated by the serum of typhus 

 patients up to 1 to 1500,— this being known as the Weil-Felix 

 reaction. 



Rocky Mountain Fever. — This is a typhus-like disease which 

 has been the subject of much investigation in America. The 

 essential pathological anatomy appears to be an inflammatory 

 reaction of .the adventitia of the vessels of the subcutaneous 

 tissue and of the genitalia, with degenerative changes in the 

 media, and a perivascular monocellular reaction. There is also 

 thrombosis in the vessels. There is evidence that the disease 

 is transmitted by a tick, dermacentor andersoni. Monkeys aud 

 guinea-pigs can be infected with the blood, and also by ticks. 

 In the guinea-pig the illness is much more severe and fatal 

 than in typhus infection. There is fever with, in the male, 

 swelling and haemorrhage of the scrotum, swelling and rash in 

 the ears, and swelling and it may be necrosis of the paws. In 

 the vessels in human cases and in infected guinea-pigs, and also 

 in the stomach of the tick, Wolbach has found bodies - 5 to 1 p 

 long, and 0'2 to 0'5 /a broad, which closely resemble the Rickettsia 

 prowazeki. According to Gumming the disease can be distin- 

 guished from typhus by the reaction in the guinea-pig. 



