754 INFECTION AND IMMUNITY. 



contagious- scntial virus. Close contact, as by kissing, or the 



ness. . , . -i p , 



common use of eating utensils is a means of trans- 

 mission. The opinion has been advanced by Weill 

 and Pehn that pertussis is contagious only during 

 the catarrhal stage of the disease. "Of ninety- 

 three non-immune children who were placed with 

 fifteen children who were in the convulsive stage, 

 none became sick" (cited by Gotschlich). This 

 point is not sufficiently established, however, to 

 warrant modifications of prophylactic measures. 

 Whooping cough is often epidemic and is more 

 common in cities where contact with the infected 

 is more likely to occur than in the country. The 

 incubation period is from seven to fourteen days. 



Isolation is more difficult than in the more acute 

 contagious diseases, yet contact with other chil- 

 dren should be avoided as much as possible, and 

 the patients should be withdrawn from school 

 until recovery is complete. 



Pertussis is almost exclusively a disease of chil- 

 dren, although older people may be attacked. Sus- 

 ceptibility is not general. One attack usually con- 

 fers immunity. A varying degree of leucocytosis 

 is excited by the infection (12,000 to 45,000), the 

 significance of which is not known. It is chiefly 

 mononuclear. 



serotherapy. Serotherapy for whooping cough has not ad- 

 vanced to a point where we can speak with as- 

 surance concerning it. Manicatide (1903) im- 

 munized horses and sheep with the organism which 

 he cultivated from a large number of cases. He 

 reports that cure may be accomplished in from 

 two to twelve days when the serum is used within 

 the first fifteen days of the disease. The bacillus of 

 Manicatide differs from the influenza-like organ- 



