CHAPTER XXIII 



THE COMMON COLD, THE PNEUMOCOCCUS AND A CONSIDERATION 

 OF THE PNEUMONIAS 



THE COMMON COLD 



IN dealing with infections of the respiratory tract of man, it is 

 impossible to avoid referring briefly to a condition, which, though 

 mild, is perhaps the most common of all such infections, is unques- 

 tionably transmitted from person to person, and yet is etiologically 

 entirely obscure. The condition is of great importance because of 

 the great loss of economic efficiency which wholesale infection of a 

 population with the common cold entails, and because of the fact 

 that the catarrhal inflammation of the nose, throat and upper 

 bronchii, which accompanies the cold, prepares a site for the lodg- 

 ment and multiplication of influenza bacilli, pneumococci, strepto-. 

 cocci, diphtheria bacilli, perhaps meningococci, and other organisms 

 that may lead to more serious disease. Also, the sneezing, coughing 

 and expectoration of individuals suffering from colds results in the 

 promiscuous distribution of bacteria lodged, by chance, in the respir- 

 atory passages of such people. Carriers of virulent organisms of 

 various kinds, such as diphtheria bacilli, meningococci, streptococci, 

 pneumococcus types I, II, and III, etc., begin, in the course of 

 their colds, to distribute the virulent organisms they carry to others. 

 They not only spread the virus that has given them the "cold," but 

 scatter a spray which contains the virulent organisms to which they 

 themselves are immune, and, therefore, not only directly infect sus- 

 ceptible contacts, but transmit to them directly a condition which 

 will make it possible for these virulent organisms to lodge in their 

 mucuous membranes, and perhaps cause the secondary more serious 

 diseases. A circuit of carrier distribution is so started, and it has 

 been variously proved that during the colder months of the year, 

 when colds abound, the carrier rate of all respiratory diseases 

 increases. If we consider that in any large group of people there 

 may be three or more per cent of meningococcus carriers, similar 



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