798 MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC ANIMALS 



infected before enlistment; ther^e were no deaths. When comparison is 

 made with the best results obtained in the army from sanitary measures 

 alone without the vaccination, Major Russell estimates that in 1913 there 

 was "only one one-hundred-and-sixty-seventh of the loss of time from 

 duty because of typhoid fever." 



Asiatic Cholera* 



Microspira comma 



The disease is endemic in parts of India whence epidemics have 

 spread throughout the world. America has been visited by several 

 epidemics and at the sea ports more frequently, chiefly New Orleans. 



The disease occurs naturally only in man. The incubation period 

 is from part of a day to ten days, usually about three days. 



In its most characteristic form the disease begins with few or no 

 prodromata. It is marked by fever, sudden onset of purging and 

 vomiting followed by cramps and severe depression. Evacuations 

 finally become almost, a colorless Uquid, "rice-water stools." The 

 cramps may occur in the whole muscular system most frequently in 

 the legs and are often extremely painful. A stage of complete collapse 

 finally occurs. There are, however, many variations from these 

 typical cases. The mortality is usually given at from 45 to 50 per 

 cent. 



Aftef death there are found extensive acute degenerative changes in 

 'the kidneys; the gastro-intestinal tract shows marked changes in the 

 lining membrane which may be necrotic, sodden and in some places 

 stripped away. 



■ The cholera vibrios may sometimes be seen in enormous numbers in smears from 

 t3^ical stools. For a positive diagnosis, however, the organism must be cultivated. 

 The usual method is to inoculate -a i per cent peptone solution from the stool, in- 

 cubating at 3v° for from four to eight hours and sowing plates from the very surface 

 of the liquid, either of gelatin or alkaline agar or both. The vibrios are m to 5m 

 long by about o.Ufi wide, and are curved slightly like a comma or sometimes in a 

 half circle. These comma forms are best seen in broth cultures. The ends 

 are usually rounded. In young cultures the organisms are usually arranged 

 singly, occasionally two may be found end to end in the form of an "S." There is 

 no capsxxle, and no spore formation. There, is a single terminal flagellum, and the 



* Prepared by Edward Fidlar. ' 



