COMMUNICABLE DISEASES. 



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In some diseases the mortality rate is very high, as in yellow fever, 

 beri-beri, tetanus, cholera, plague and leprosy. In others it is low, as in 

 syphihs, gonorrhea, malaria, whooping cough, mumps and varicella. In cer- 

 tain diseases the prognosis is rather uncertain, the n^ortahty rate being high 

 at times and again low, as in scariatina, small-pox, measles and grippe. Some 

 diseases run a somewhat variably rapid course as pneumonia, diphtheria, 

 spinal meningitis, bubonic plague and Asiatic cholera, ending either in death 

 or recovery. Other diseases, as scariet fever, measles and diphtheria may 

 have after-effects or sequete which often assume a chronic course and may 

 finally result in death. Certain diseases run a regular course which varies 

 but little as to the sequence of symptoms and duration, as typhoid fever 

 (five weeks). Others run a variably chronic course, ending either in death 



