i8 4 INFECTION AND IMMUNITY 



" If the observer limits his field of examination and judgment 

 to certain parts of Europe and the United States, he may find 

 little clinical evidence of the active spread of leprosy by con- 

 tagion. Observation shows that leprous germs introduced into 

 these favoured regions do not take root and spread; they rarely 

 survive the death of the leper. In New York, for example, large 

 numbers of lepers coming from countries where leprosy is en- 

 demic have lived for years, many of them have been sent to gen- 

 eral hospitals, where they have died, and yet, so far as is known, 

 no case of indigenous leprosy can be traced to association or 

 contact with these patients. The same experience has been 

 noted in London, Paris, and Berlin, where lepers from other 

 countries have flocked for treatment and have been received in 

 the general hospitals without special measures of isolation, and 

 yet no case of leprous contamination has been traced to contact 

 with them." 



The same author calls attention to the fact that 

 one hundred and sixty Norwegian leper immigrants 

 have settled in our Northwestern States, where most 

 of them have eventually died, but no cases have oc- 

 curred among those associated with them. On the 

 other hand, leprosy has extended in Louisiana, in 

 the Sandwich Islands, and in many other parts of 

 the world, as a result, apparently, of the introduction 

 of cases from other endemic foci of infection. 



Morrow believes that the main factors which lead 

 to the propagation of the disease are individual 

 predisposition and insanitary surroundings. Certain 

 authors insist that a fish diet has the effect of estab- 

 lishing a predisposition to the disease. In support of 



