380 PATHOGENIC MICROORGANISMS 



vertical lines across the dashes and see where and how sanitary 

 interference may interrupt the progress of transmission. Thus, in 

 the prevention of the intestinal infections, the municipal and state 

 authorities must care for the water supplies and sewage disposal 

 plants ; the administrative public health authorities must be supplied 

 with a reporting system for the early recognition and demarkation 

 of foci, and must epidemiologically attempt to trace existing cases 

 to their sources, following this with carrier examinations of sus- 

 pected small groups ; physicians must act as the first line of defense 

 in regard to early diagnosis, intelligent, immediate isolation and the 

 collection of the first significant epidemiological information for the 

 use of the health authorities; city cleaning departments and other 

 agencies must aid in preventing fly breeding, in garbage disposal, 

 etc., and last but not least, general educational campaigns must 

 elicit the intelligent cooperation of the public by supplying the 

 simple information which is necessary for individual protection. As 

 a matter of fact, if the public realized that most cases of typhoid 

 and the paratyphoid fevers could be suppressed at the present time 

 by a regular hand washing after defecation and before meals, the 

 problem would be largely solved. 



(3) The third group comprises diseases in which intimate contact 

 between infectious material and the external surface of the body 

 of the new victim is necessary. In some of these diseases trans- 

 mission can take place without a visible break in the skin, as perhaps 

 in plague, rabies, syphilis and some others, where the lesion through 

 which the virus can enter may be so microscopical in size that no 

 visible trauma is apparent. In others, such as the pyogenic infec- 

 tions, glanders, anthrax and the anaerobic infections, trauma of 

 some kind is usually necessary. Few of these diseases can ever 

 become epidemic to any great extent in the ordinary sense of the 

 word. Some of them, however, like the venereal diseases may be 

 regarded as so plentifully endemic, owing to the nature of their 

 transmission, that we may look upon the present condition of com- 

 munities as subject to a constant subacute epidemic state. Venereal 

 diseases are a special sanitary group which requires individual 

 treatment which we cannot enlarge upon in this place. 



(4) In the fourth group are those diseases which are transmitted 

 by insects. Such are malaria, yellow fever and dengue fever, trans- 

 mitted by different species of mosquitoes, African sleeping sickness, 

 pappataci fever, transmitted by flies, Rocky Mountain spotted fever 





