RATS 149 



From what has been said it is obvious 

 that rats cause enormous damage to humanity, 

 which is counterbalanced by the almost 

 infinitesimal good they do as scavengers. I do 

 not propose to consider in detail the harm 

 they do as disease-carriers, but one cannot 

 forget that the rat is the primary host of 

 Trichinella spiralis, which, when conveyed 

 from the rat to the pig, and — by eating un- 

 cooked or imperfectly cooked pork — from the 

 pig to man, causes severe and very fatal 

 epidemics, and enforces the expenditure of 

 large annual sums on meat inspection. They 

 further convey a virulent form of equine 

 influenza from one stable to another, and also 

 the ' foot-and-mouth ' disease. But what is 

 infinitely more important to man than all the 

 other injuries put together is the harm they 

 bring to suffering humanity by conveying, 

 the bubonic plague from one patient to 

 another. The plague under which India and 

 great parts of Burma are ' groaning and 

 travailing,' is caused by a specific bacillus 

 discovered in 1894 by Yersin at Hong-Kong. 

 It flourishes in other vertebrates besides man 

 and the rat, but, owing to the migratory 

 habits of the latter, the rat is the most effective 

 agent in the spread of the disease. Both 

 species of rat seem about equally susceptible, 

 and the presence of the microbe showed no 



