COMMUNICABLE DISEASES. 



22 3 



Name of disease. 



Incubation 



period, 



days. 



Primary cause. 



Nature of 

 communicability. 



Carriers or sources 

 of infection. 



Vaccinia. . . 



3-6 



Unknown Contagious by inocu- 

 lation only. 



Cow virus, human 

 vaccinia. 



Varicella, chick- 

 en-pox. 



14-15 Unknown Contagious Those affected. 



Whooping cough.. 



Unknown Very infectious 



Exposure to those 

 affected. 



Dengue 



Protozoa ? . . . . Infectious . 



Mosquito (culex fati- 

 gans) . 



'Pneumonia 



Micrococcus pneu- Infectious, 

 moniae (Diplococ- 



cus). 



Carried by persons. 



Dysentery (bacil- 

 lary) 



Amoeba dysenteriae. Infectious Polluted water supply. 



Malta fever. . . 



Beri-beri. . 



6-10 



Micrococcus meli- Infectious 



tensis. 



Goats' milk, stings of 

 insects. 



Months. Micrococcus? Infectious A tropical disease. 



Pellagra. 



Aspergillus species.. Neither infectious nor 

 contagious. 



Mouldy foods, corn 

 especially. 



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 

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

 tain diseases the prognosis is rather uncertain, the mortality rate being high 

 at times and again low, as in scarlatina, 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 scarlet fever, measles and diphtheria may 

 have after-effects or sequelae 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 



