760 MICROBIOLOGY OF DISEASES OP MAN AND DOMESTIC ANIMALS 



The only remedy seems to be the recognition of the principle that 

 harboring or having in possession a case of infectious disease, unknown 

 to the proper officials, is a crime against society, and that the excuse 

 that the person harboring such case did not know it to be such should 

 be of no more weight than the plea of ignorance of the law which is 

 not allowed in other and often far less serious matters. 



The official isolation of infectious cases involves also official responsi- 

 bilities regarding the release from isolation after the acute attack is 

 over. Officially to declare a person dangerous to the community does 

 no harm to the community if a mistake is made. An official declaration 

 that a person is no longer dangerous and is therefore free to enter into 

 the community life again may, if mistaken, result in a widespread 

 outbreak. No more delicate task confronts the public health official 

 than the making of this decision. 



In diphtheria, the examination of cultures from the throat and nose 

 of the person in question and the repeated failure to find the bacterium 

 of diphtheria is usually considered a safe criterion. In scarlet fever, 

 complete and continued restoration of the throat and nose to normal 

 conditions, together with absence of ear discharges, should be required, 

 yet is not perfect; for it is not very unlikely that the scarlet fever 

 infective agent, whatever it may be, can continue in a recovered scarlet 

 fever throat as the diphtheria bacterium may remain in a recovered 

 diphtheria throat. In other diseases the decision is based on similar 

 lines the disappearance of crusts in smallpox and chickenpox, of 

 discharges in measles, on restoration to normal of whooping cough; 

 but in all these diseases the analogy with diphtheria may hold to a 

 greater or less extent. In tuberculosis, the patient is infective as long 

 as Bact. tuberculosis can be found in the sputum; in typhoid fever the 

 patient is likewise infective as long as the urine or faeces show the 

 typhoid bacillus. In these two diseases, however, quarantine or 

 even isolation is not officially carried out nor release from restriction 

 officially given to any great extent or with any marked uniformity. 



Full sanitary nursing precautions regarding a typhoid fever patient's 

 discharges should continue for an average of three months after 

 recovery. 



PUBLIC HEALTH METHODS 



By request of the editor, there are here inserted the rules followed^n the isola- 

 tion and quarantine of the ordinary infectious diseases in London, Canada, where 



