20 



Rats ajid Mice 



Trichina are born, and their migration commences, there is further 

 fever, exhausting diarrhoea, and much pain and swelhng in the 

 muscles. The chance of surviving infection depends upon the 

 vitahty of the patient and the extent to which he is infected. If he 

 survives the migration and encystment of the young Trichina he 

 will be safe, since the parasites now become inert, but he may feel 

 bad effects from their presence for many years. Mortality in cases 

 of trichinosis is high ; in one instance a single pig, converted into 

 sausages, caused 337 cases of trichinosis, and of these 101 

 terminated fatally. 



The pig is infected with Trichina by devouring the bodies of 

 dead rats and mice, or food fouled by the excrement of these 

 animals. The Common Eat is the chief host of the parasite ; the 

 latter is, however, not uncommon in the House Mouse. Eats and 

 mice devour the bodies of their fallen comrades ; they do not 

 despise food contaminated with their droppings ; and rats feed 

 upon the dung of other animals. Further, in slaughter-houses, 

 rats often have an opportunity of feeding upon the trimmings from 

 trichinous flesh ; in Glasgow City Abattoir 3 per cent, of the rats 

 were found to be trichinous. In these various ways these rodents 

 ensure the continued existence, abundance, and wide dissemination 

 of T. spiralis. 



Sokodu, or Eat-bite Fever, results from infection ensuing 

 upon the bite of a rat. The wound is said to heal rapidly and 

 apparently normally, but after an incubation period, varying from 

 a few days to a month, it becomes inflamed and painful. This is 

 followed by rapid variations in temperature, and symptoms of 

 serious systemic infection ; the kidneys in particular are badly 

 affected. Death may occur from nephritis, or from exhaustion. 

 If not immediately fatal, the disease assuities a relapsing form ; 

 its course may extend over several months. In one case it 

 developed into a progressive wasting with recurrent fever lasting for 

 eight years. (For further details and treatment see Longman, p. 26.) 



Influenza in an acute form occurs among horses, and it is 

 conveyed from stable to stable by rats. Where the outbreak of 

 the disease has led to the closing of a stable, the disease usually 

 appears promptly in the other stables of the neighbourhood, 

 because the rats migrate from the closed stable so soon as their 

 food supply stops. An even more striking illustration is afforded 

 by the outbreaks of equine influenza among the ponies of adjoining 

 coal mines. 



