RICKETTSIA BODIES 645 
morbidity, which was recognized for the first time during the World 
War. The prodromal symptoms are not distinctive ; the onset is usually 
sudden and associated with headache, general malaise and nuiscidar 
weakness, congested conjunctivte, together with an enlarged and hard 
spleen, and frequently a rash suggestive of that of typhoid fcAer. 
The head, back and joints ache painfully, although the latter are not 
swollen, and pains in the shins are distinctive, although not always 
present. In some respects the disease resembles influenza. Swift^ 
recognizes three types of febrile reaction: (1) a single short fever, 
resembling that of influenza in its general features; (2) a regular or 
irregular intermittent or relapsing febrile reaction, and (3) a longer 
sustained fever with moderate remissions, suggesting enteric fever. 
Koch- believed trench fever to be a mild or abortive type of recurrent 
fever. 
The blood picture is not distinctive and in general the close resem- 
blance of the clinical features to other well-known infections has 
doubtless been a potent factor in preventing an earlier recognition 
of the disease. 
The first important contribution to the disease was the proof of 
its transmissibility to normal individuals by the injection of blood 
from an infected individual in the acute stage. The incubation period 
varied from five to twenty days. It was believed at first that the virus 
was intracorpuscular and not present in the serum of patients, but 
subsequent studies^ by the Research Committee of the American 
Red Cross showed that citrated plasma contained the infective agent. 
This observation was confirmed by the British Commission.^ 
The natural mode of transmission is through the louse." Infected 
lice placed upon normal subjects induced the disease in volunteers 
after a latent period of from one to two weeks. It appears that lice 
do not become infective until a minimal period of about five days 
from the time of biting an infected individual has elapsed. Patients 
may be infective for lice for months. The injection of crushed lice 
was unsuccessful in inducing infection, although the virus appears to 
withstand drying in the feces of lice for several days. The virus is 
occasionally demonstrable both in the urine and sputum of trench 
fever patients. 
The nature of the virus awaits adequate confirmation. Nankivell 
and SundelF believed a spirochete, smaller and less undulant than 
Treponema pallidum, was the inciting agent. Couvy, Dujarric and 
Riviere^ described two varieties of spirochetes observed in the blood 
1 Jour. Am. Med. Assn.. 1919, 73, 1807. 2 Deutsch. med. Wchnschr., 1917, p. 1425. 
3 McKee, Renshaw and Brunt: British Med. Jour., 1916, i, 225. 
^ Report on Trench Fever, Medical Research Committee, American Red Cross, 
Oxford, 1918. 
^ Byam, Carroll, Churchill, Lloyd, Sorapure and Wilson: Trans. Soc. Trop. Med. 
and Hyg., 1918, 11, 237. 
•= Davies and Weldon: Lancet, 1917, i, 18.3. ' Lancet, 1917, ii, ()72. 
8 Compt. rend. Soc. de biol., 1918, 81, 22. 
