VACCINES IN PROPHYLAXIS OF DISEASE 219 



first two years of life. Almost everybody is 

 susceptible and the majority of persons have 

 the disease sometime during their life. Sus- 

 ceptibility decreases with age, but it may be 

 seen in adult life and even in old people. 



Cause The cause of whooping-cough is a 

 small bacillus first described by Bordet and 

 Gengou in 1900 and isolated in pure culture by 

 Bordet in 1905. The bacillus is called Bacillus 

 pertussis or sometimes the Bordet bacillus. The 

 causal relation of the Bordet bacillus to whoop- 

 ing-cough was demonstrated by Mallory, who 

 examined the trachea and lungs of three patients 

 that died of whooping-cough in the Boston City 

 Hospital. Moreover, Mallory successfully inocu- 

 lated animals and produced the typical disease, 

 and succeeded in recovering the bacillus in pure 

 culture from the tissues of the animal after it 

 was killed. 



Vaccination Any means for efficient prophy- 

 laxis against whooping-cough is of inestimable 

 value. While the use of a vaccine for prophy- 

 laxis against this disease is rather recent, nev- 

 ertheless it has already attained a place for 

 itself in immunology and has demonstrated the 

 rationale of thus immunizing against the dis- 



