HOW TYPHOID FEVER IS CONVEYED. 461 



importance ; and yet it is one on which the most antagonistic opinions 

 are held. 



Among the many ailments which may be transmitted from the sick 

 to the healthy, the ones with which we are most familiar in this coun- 

 try are those which are grouped together iinder the name of "the 

 eruptive fevers." To this group typhoid fever belongs. It includes 

 also small-pox, typhus fever, scarlet fever, and measles. Each consists 

 of an attack of fever of more or less definite duration, and of a local 

 inflammation or eruption : during the course of each its poison is 

 largely reproduced in the system ; and each may be transmitted from 

 the sick to the healthy. 



There are several ways in which a disease may be transmitted : 



1. Its poison may be introduced directly by inoculation, as is daily 

 done in the case of vaccination, 



2. It may pass directly into the surrounding atmosphere from the 

 persons of the sick, and be inhaled by those in their neighborhood, as 

 constantly happens in small-pox, typhus fever, measles, and scarlet 

 fever. 



3. It may be conveyed indirectly, and to a distance, in articles of 

 clothing, bed-linen, etc., and, passing from them, may be inhaled by 

 those who wear or handle them, as often happens in the same diseases. 

 Or it may be conveyed in food or water, and enter the system through 

 the digestive organs, as frequently happens with the poison of typhoid 

 fever. 



When we wish to say that a disease is transmitted from person to 

 person, without defining the mode of transmission, we say that it is 

 coMMUJfiCABLE, The term is a general one, which includes every mode 

 of transmission. 



When we wish to say that a disease may be transmitted by inocu- 

 lation, we say that it is inoculable. 



When we wish to say that the poison may be conveyed in articles 

 of clothing, in linen, in food, in water, etc., we say that these articles 

 have been infected by the poison, and that the disease is iis^fectigus. 



When we wish to say that a disease is produced by personal con- 

 tact with one suffering from it, and that the danger of catching it 

 increases with the closeness and intimacy of such contact, we call it 



CONTAGIOUS. 



A contagious disease, therefore, is one in which the danger of con- 

 tracting it increases as we approach, and diminishes as we recede from, 

 a person suffering from it. It is contactuous. 



Contagion may be defined as direct infection ; and infection as in- 

 direct contagion. In both a poison passes from the sick to the healthy. 

 It is the difference in the mode of conveyance of the poison that makes 

 the difference between the two. The distinction is one of the utmost 

 practical importance, and must be borne in mind in discussing the 

 question of the contagiousness of any disease. An ailment may be 



