TYPHUS AND MONKEYS 335 



eastern provinces, and in Algeria, Tunis, and Morocco. 

 It is a disease of cold and temperate climates rather than 

 of the tropics. 



In the last century typhus was distinguished definitely 

 and clearly from " typhoid " or "enteric" fever, and from 

 "relapsing" or "famine" fever, with which it had pre- 

 viously been confounded. The bacterial germs causing 

 enteric and relapsing fevers are now known, and have been 

 isolated and cultivated, and the mode in which they are 

 conveyed into the body of a previously healthy patient is 

 ascertained. But until the past year we knew neither 

 the parasitic germ which causes typhus fever nor the 

 mode by which it passes from one individual to another. 

 A vague idea that it was spread through the air prevailed. 

 Typhus is remarkable for the frequency with which the 

 nurses and doctors attending a case become infected. 

 About 20 per cent, of those attacked by it die, but in 

 persons above forty-five years of age the mortality is much 

 greater — about half succumb. 



Dr. Nicole and his colleagues of the Institut Pasteur in 

 Tunis have recently had the opportunity of studying 

 typhus there. They found that the ordinary local monkey 

 could not be made to take the disease. But a drop of 

 blood of a typhus patient injected into a chimpanzee 

 (which is far nearer akin to man) produced the disease 

 after an incubation period of three weeks. This fact was 

 definitely established. From what is now known as to 

 relapsing fever, malaria, yellow fever, plague, and sleeping- 

 sickness, it seemed probable that some migratory insect 

 must be the carrier of the typhus infection from man to 

 man. The typhus patients brought into the hospital at 

 Tunis were carefully washed before admission, and no 

 infection of other patients or nurses took place in the 

 wards, although the cases were not isolated, and bugs 

 were abundant. The only cases of infection which 



