494 PATHOGENIC MICROORGANISMS 



question, on the other hand, finds that the roots of the epidemic go 

 far deeper than this, since his studies of statistics of respiratory 

 diseases in the United States seem to show that as early as December, 

 1915, and January, 1916, there occurred, in New York and Cleveland, 

 sudden and considerable rises in mortality from respiratory dis- 

 eases. In January, 1916, influenza was reported in twenty-two cities 

 of the Union. These epidemics were mild and attracted little at- 

 tention. 



During the winter of 1917, many so-called cases of influenza 

 occurred in Europe among French and British troops. In the winter 

 of 1917, similar cases, supposedly influenza, appeared in many Ameri- 

 can camps. MacNeal states that in November and December, 1917, 

 and January, 1918, there were many cases of so-called influenza in 

 the American Expeditionary Forces. The disease appeared without 

 question at Camp Oglethorpe in March, 1918, a month before it was 

 recognized in any numbers in Europe, almost at the same time at 

 which it seems to have appeared in Spain. 



It cannot be said with definifeness just where the lasi epidemic 

 began, but if we summarize the evidence available at the present 

 time, it would seem that Frost is probably right in that it did not 

 begin in a single place, as previous epidemics are said to have begun, 

 but started in a great many different places almost at the same 

 time. 



Like other epidemics it appeared in successive waves, the first 

 wave probably beginning in 1917 in some places, in the spring of 

 1918 in others. There was an interval, and then in September and 

 October of 1918 the second wave had gathered its full velocity. This 

 was the really fatal wave all over the world. The mortality was 

 enormous. Pearl estimates that in the United States alone, deaths 

 from influenza were not less than 550,000 and this is approximately 

 five times the number (111,179) of American soldiers officially stated 

 to have lost their lives from all causes in the war. In the Surgeon 

 General's report it is stated that influenza, with its complications, 

 is charged with 688.86 admissions of American and native troops 

 for the year 1918, and caused 23,007 deaths, practically 82 per cent 

 of all deaths in the Army being attributed to respiratory diseases. 



Morphology and Staining. The bacillus of influenza 23 (Pfeiffer 

 bacillus) is an extremely small organism, about 0.5 micron long by 



23 Pfeiffer, Deut. med. Woch., ii, 1892; Zeit. f. Hyg., xiii, 1892; Pfeiffer und 

 Beck, Deut. med. Woch., xxi, 1893. 



