BORDETrGENGOU BACILLUS 



505 



respiratory infections, and the general infectiousness is very high, 

 since susceptible children definitely exposed do not often escape. 

 After the disease has set in, the patient may remain infectious for 

 others all through the disease and long into convalescence. It is 

 best to keep children isolated for several weeks after the cough 

 has subsided. It has been possible to reproduce conditions simu- 

 lating the disease in monkeys and in dogs, and there is a suspicion 

 that the disease may be transmitted by domestic animals, especially 

 dogs. Though this is not absolutely certain, Rosenau and other 

 sanitarians advise care in this regard. 



Prevention consists in early diagnosis and isolation, exclusion 

 from school and absolute avoidance of close contact with other 

 children. Quarantine should continue, as stated above, for several 

 weeks after the cough has completely subsided. 



In 1900 Bordet and Gengou 2 observed in the sputum of a child 

 suffering from pertussis a small ovoid bacillus which, though similar 

 to the influenza bacillus, showed a number of morphological char- 

 acteristics which led them to regard it as a distinct species. As they 

 were at first unable to cultivate this organism, their discovery 

 remained questionable until 1906, when cultivation succeeded and 

 the biology of the microorganism was more fully elucidated. 



Morphology. The morphology of this organism is described by 

 them as follows: The organism in the sputum, early in the disease, 

 is scattered in enormous numbers indiscriminately among the pus 



** 



FIG. 53. BORDET-GENGOU BACILLUS. 



cells, and at times within the cells. It is extremely small and ovoid, 

 and frequently is so short that it resembles a micrococcus. Often 

 its polos stain more deeply than the center. In general, the form 



- Bordet et Gengou, Ann. de 1 'inst. Pasteur, 1906. 



