COMMUNICABLE DISEASES 37 1 



interval of space. Itch, for example, is contagious, but not in the least 

 infectious, whereas whooping-cough is infectious, but not contagious. 

 Some diseases are both contagious and infectious, as small-pox and diph- 

 theria. Malaria and yellow fever are infectious, but not in the least con- 

 tagious. Since the distinction between contagious and infectious diseases 

 cannot be clearly drawn, these term are discontinued and the term com- 

 municable diseases is substituted therefor. By communicable disease 

 we mean any disease which may be transferred from the sick to the well, 

 either directly through close contact or indirectly through more or less 



>i V -x^ I 



Fig. 88. — Bacillus anthracis. This bacillus is spore-forming and causes the cattle 

 disease known as anthrax. This disease is especially common among sheep and cattle 

 and may be transmitted to man, especially those working with the wool, hides and 

 meat of infected animals. The two chief forms of anthrax in man are mahgnant P"st"le 

 and woolsorter's disease. The dried spores of this bacillus will live for years and will 

 withstand the boiling temperature for hours. Vaccinating animals against anthrax is 

 commonly practised now. Anthrax is frequently confused with glanders, an equine 

 disease caused by the Bacillus mallei, a. Non-spore-bearing bacilli; b. chains of cells; c, 

 spore-bearing bacilli. Cell-walls and plasmic contents are stained, the spores are un- 

 stained. 



distance in space. A pandemical disease is one which spreads over or 

 pervades the entire earth. La Grippe or influenza is such a disease. The 

 last pandemic destroyed more lives than were kUled during the entire 

 period of the World War, and this despite the fact that the mortahty rate 

 in this disease is not high. The case rate was very high, about equal m 

 numbers to the entire armies engaged in the World War. In the past Asi- 

 atic cholera and plague have been pandemical in scope. In modern times 

 pandemics are prevented by the national quarantine services, and any 

 extensive epidemic in any country or state is prevented by the state and 

 community quarantine. That is, this is certainly true as far as the disease 

 are concerned concerning which we know the cause. The only reason 

 why influenza became pandemical is because we are not as yet aware ol 

 the primary cause. A disease which is more or less wide spread over a 

 country is spoken off as an epidemic. For example, cerebrospinal mening- 

 itis and pneumonia may be epidemical. Diphtheria is often epidemic m a 

 community, and as above stated, it is likewise infectious and contagious. 



