INFLUENZA THE DISEASE AND ITS EPIDEMIOLOGY 483 



The characteristics of such cases are as follows : the onset is almost 

 regularly abrupt. Typical cases become ill suddenly, without pre- 

 monition. More rarely there are a few days of general tired feeling 

 and malaise, but this is unusual. The first symptoms consist in head- 

 ache, feverishness, loss of appetite, pains in the back and somatic 

 muscles, particularly in the calves of the legs ; sometimes suffusion and 

 burning of the eyeballs, and often mild sore throat. The temperature 

 rises to anywhere from 101 to 104, and this condition continues for 

 two or three days, when the patient gradually returns to normal, but 

 is left quite exhausted. Very oc<?asionally, skin rashes appear in the 

 form of erythematous patches, not at all uniform in appearance and 

 difficult to characterize dermatologically. The spleen is usually not 

 enlarged. The leucocytes range from 5,000 to 9,000. 



Such cases, if they develop respiratory complications at all, suffer 

 from nothing much more than a mild laryngitis or bronchitis, which 

 appears toward the third or fourth day and rapidly subsides. The 

 first 200 or 300 cases which we saw during the last epidemic, among 

 American soldiers in France, developed practically no respiratory 

 symptoms whatever and no focal lesions anywhere. The disease was 

 so brief and mild that it was not recognized as influenza at first, and 

 was spoken of as "three-day fever." The morbidity at such times is 

 high, the mortality practically nil. 



As we study the literature of past epidemics and the observations 

 made on the last epidemic in different places, we find that this experi- 

 ence has been universal. In the 1898 epidemic, Hey f elder speaks of 

 Siberian fever, which was at first looked upon as malaria, and noted 

 the absence of catarrhal symptoms in the respiratory organs. Just 

 before this, the epidemic outbreak in Constantinople was spoken of as 

 "dengue fever," and similar, unrecognized, mild cases characterized 

 the beginnings of the epidemic in Petrograd. During the war-epidemic 

 of 1917 and 1918, Vaughan and Palmer also noted the uncertain and 

 mild characters of the first cases at Camp Oglethorpe (in March, 1918) 

 and in Italy, San Pietro suggested sand-fly fever as a possible diag- 

 nosis. 



These considerations may seem irrelevant in a book of this char- 

 acter, but are important in indicating that etiological investigations 

 on influenza must include a careful study of cases of this kind. In 

 the later periods of the first epidemic waves, as well as in the second 

 and third waves, the overwhelming majority of the cases, because of 

 secondary infection, are respiratory in -character, an important 



