October 3, 1919] 



SCIENCE 



317 



tygiene, applied on the individual scale of 

 safeguarding one person from another, the 

 most difficult of all hygienic regulations to 

 enforce. 



Eetuming now to epidemic poliomyelitis, 

 we may fairly claim that we are in possession 

 of the essential facts which, if widely ap- 

 plicable, should enable us to control the spread 

 of that disease. But we can, I think, hardly 

 claim that up to the present time our accom- 

 plishments in that direction have been re- 

 markable. It is sufficient merely to compare 

 the curve of incidence of the Swedish epi- 

 demic of 1905, before the nature and mode of 

 infection of poliomyelitis were known, with 

 those of the last several years in Massachu- 

 setts and 'New York state for example, in 

 order to conclude that the progress of the 

 epidemics in the several places was practically 

 identical. 



And, indeed, this is what might be expected 

 in view of the difficulties surrounding the 

 prompt and accurate diagnosis of poliomye- 

 litis in its atypical and abortive, often am- 

 bulant forms. Once the disease is introduced 

 under conditions favoring its epidemic spread 

 a wide dissemination of the inciting micro- 

 organism takes place, and a constantly in- 

 creasing number of persons becomes exposed 

 to its presence, before any restrictive measures 

 are put into effect, and indeed also after they 

 have been applied. In the case of poliomye- 

 litis, as in that of influenza itself, a wide 

 distribution of the infectious agent precedes 

 the enforcement of preventive sanitary regula- 

 tions. These considerations do not, of course, 

 warrant intermission of the protective meas- 

 ures now in use, which undoubtedly save many 

 individuals from exposure and thus from po- 

 tential attack; they do, however, offer an ex- 

 planation of why, up to the present time, 

 greater success has not attended efforts at 

 control once the epidemic is under full way. 



The case with the epidemic pneumonias is 

 of another order. They represent theoretically 

 two diseases which should respond to methods 

 of control based upon our knowledge of their 

 mode of infection. In the epidemic strepto- 

 coccus pneumonia and the pneumonia follow- 

 ing influenza we are dealing with pathological 



conditions in which not a newly introduced, 

 extraneous microorganism is operating widely 

 and insidiously, but in which the active mi- 

 crobes concerned are examples merely of in- 

 tensified races of common and almost omni- 

 present species belonging to the flora of the 

 nasopharynx. The infectious agents in these 

 instances are contained within the nasal, 

 buccal and bronchial secretions, and are dis- 

 seminated in the sprayed material which is 

 coughed or otherwise thrown into the sur- 

 roundings of the patients. The lesson there- 

 fore to be derived from the severe experience 

 of the recent pneumonia epidemics is to the 

 effect that measles and influenza patients are 

 not to be assembled into large groups or kept 

 in open wards, but should be placed in sep- 

 arate rooms or cubicles, where they and their 

 attendants may be preserved as far as possible 

 from sputum droplet contamination. In the 

 instance of epidemic pneumonia a chain of 

 direct infection from one patient to another 

 tends to be established, and hence the sanitary 

 control of those diseases is to be sought 

 through the breaking, as it were, of this 

 vicious circle. 



A distinction has now been intimated in the 

 possibilities of direct sanitary control between 

 the two epidemic diseases — namely, poliomye- 

 litis and influenza — introduced from without, 

 and the pneumonias, which are mere, if in- 

 tense, exaggerations of sporadic diseases or- 

 dinarily prevailing. I propose now to lay be- 

 fore you a suggestion as to means of attacking 

 the exotic epidemic diseases which may come 

 to merit serious attention. 



Epidemic diseases in the commonly accepted 

 sense have fixed locations — the so-called en- 

 demic homes of the diseases. In those homes 

 they survive without usually attracting special 

 attention over often long periods of time. 

 But from time to time, and for reasons not 

 entirely clear, these dormant foci of the epi- 

 demics take on an unwonted activity, the 

 evidence of which is the more frequent ap- 

 pearance of cases of the particular disease 

 among the native population and sooner or 

 later an extension of the disease beyond its 

 endemic confines. Thus there are excellent 

 reasons for believing that an endemic focus of 



