502 



SCIENCE 



[N. S. Vol. XLIX. No. 1274 



vention : First, public indifference. People do 

 not appreciate the risks they run. The great 

 complexity and range in severity of the re- 

 spiratory infections confuse and hide the 

 danger. The infections vary from the com- 

 mon cold to pneumonia. They are not all 

 separate entities by any means. An attack 

 which begins as a coryza or rhinitis may 

 develop into a pharyngitis, tonsilitis, laryn- 

 gitis,- bronchitis or pneumonia. The gravity 

 increases with the progress toward the lungs. 

 The infection sometimes seems to begin in the 

 chest, sometimes in the throat, sometimes in 

 the head. It may stop where it started or 

 pass through several phases. This is the story 

 of the common cold. It is generally more 

 discomforting than dangerous. Most people 

 get well without skillful treatment, or indeed 

 any great interference with business. N"o 

 specific virus is known to produce it. 



There is another group of diseases, a more 

 unusual one, which is often at first confused 

 with the foregoing. This includes the specific 

 infections such as diphtheria, measles and 

 scarlet fever. Influenza is in this class. The 

 symptoms at the b^inning may be identical 

 with those of the common cold and the true 

 nature of the disease escape notice until the 

 patient shows unmistakable and alarming 

 symptoms. By that time other persons may 

 be infected. 



The second factor which stands in the way 

 of prevention is the personal character of the 

 measures which must be employed. The 

 enteric infections can be controlled by pro- 

 cedures of a general sort which impose no 

 great restriction upon the conduct of the in- 

 dividual, but this is not true of the respir- 

 atory infections. The waste products of in- 

 fluenza containing the infective virus are not 

 deposited in a vessel or sewerage system where 

 they can be properly dealt with, as in typhoid. 

 The excreta of the nose and throat are 

 projected into the air and allowed to pollute 

 the hands, the food, the clothing and, in fact, 

 the entire environment of the infected person. 

 This is done unconsciously, invisibly, unsus- 

 pectingly. General methods directed against 



this kind of germ distribution must neces- 

 sarily be of limited value. 



It is an epidemiological point of great in- 

 terest that the kind of preventive measures 

 which must be taken in order to control the 

 respiratory infections devolve upon the per- 

 sons who are already infected, while those 

 who are liable to contract the disease can do 

 little to protect themselves. The burden is 

 placed where it is not likely to be well carried. 

 It does not lie in human nature for a man 

 who thinks he has only a slight cold to shut 

 himself up in rigid isolation as a means of 

 protecting others on the bare chance that his 

 cold may turn out to be a reaUy dangerous 

 infection. 



Third, the highly infectious nature of the 

 respiratory infections adds to the difficulty of 

 their control. The period of incubation varies 

 considerably; in some infections it may be as 

 short as a day or two. And the disease may 

 be transmissible before the patient himself is 

 aware that he is attacked. 



This list of the obstacles which stand in the 

 way of controlling the respiratory diseases 

 may fittingly be closed by remarking that 

 healthy persons often carry about in their 

 persons the germs of disease, thereby uncon- 

 sciously acting as a continuing danger to 

 themselves and a menace to others. It is not 

 to be wondered at, therefore, that of all the 

 things which were done to stop the spread of 

 influenza, nothing seems to have had any 

 material effect upon it. 



This may all seem very discouraging but it 

 need not depress anybody. The control of 

 typhoid once seemed an impossible task. To 

 rightly measure a difficulty is often the first 

 step toward overcoming it. 



What is said here of the influenza pandemic 

 is put forward only as the writer's view at 

 the present time. Nobody can now speak 

 authoritatively upon this subject. When all 

 the facts are brought together some of the 

 ideas which are held to-day may be foimd to 

 require modification. We are still too close 

 to the event to fully measure it. Individual 

 researches and the efforts of innumerable 

 workers, must be reported and evaluated. The 



