CHAPTER XVIII. 



ORIENTAL PLAGUE. RELAPSING FEVER. TYPHUS FEVER. YELLOW 



FEVER. 



THE PLAGUE. 



THE plague is a highly infectious disease, having its origin in 

 putrefaction and filth, in tropical climates. The virus in its effects 

 resembles that of typhus. The period of incubation varies from a 

 few hours to a week. The disease produces high temperature and 

 decomposition of the blood, and dark hseinorrhagic patches appear 

 on the skin, but there is no eruption. Lymphatic inflammation and 

 buboes almost invariably occur. The virus is intensified by warmth 

 and overcrowding in houses, and dissipated by exposure to fresh air. 



When the plague occurred in this country it was recognised as a 

 foreign pestilence from the East, and once imported it was fostered 

 and intensified in virulence wherever there was filth, putrefaction, 

 and overcrowding. The disease, like the small-pox, was communicated 

 from one person to another. If a case occurred in a house other 

 inmates were liable to suffer from the disease, while visitors to the 

 house ran a similar but less risk. There was a good deal of variation 

 both in the infectivity of the virus and in the susceptibility of 

 individuals, so that one contemporary writer remarked that " no 

 one can account for how it comes to pass that some persons shall 

 receive the infection and others not.' ; 



Medical men were credited with enjoying an extraordinary degree 

 of immunity, though there were members of the medical profession 

 who undoubtedly died of the plague. This tradition has been 

 supported, to a certain extent, by the experience of the plague 

 in modern times. In the epidemic in Egypt, in 1835, of the ten 

 French physicians engaged there, only one died ; and while those 

 who buried the victims of the plague were liable to suffer from 

 it, and many did so, yet the medical men made more than one 

 hundred post-mortem examinations without any death resulting. 



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