SPECIAL FORMS OF CONJUNCTIVAL INFECTION 147 



them. The contagiousness is so very great that every one of the 

 fifteen inoculations which have so far been made, and mostly with 

 pure cultures, have caused the disease (Morax, Weeks, Weichsel- 

 baum, MUller, Hofmann, and Luerssen). Hofmann obtained this 

 result with cultures 110 to 120 hours old. Only once did Muller fail 

 to obtain a positive result on inoculating his own conjunctiva with an 

 attenuated virus (how reduced was not stated). Even in Weeks' six 

 inoculations with mixed cultures five were positive. 



An almost invariable susceptibility therefore appears to exist. 

 Koch-Weeks conjunctivitis is to be classed with the most contagious 

 infectious diseases which we know of. The course of these arti- 

 ficially induced inflammations and the findings in their secretions 

 quite correspond to those of the original affection from which the 

 material was obtained. By continuous instillations for several hours 

 of a sterilized (heated to 58 C.) or of a filtered culture, Morax and 

 Elmassian obtained a transient catarrh of the human conjunctiva. 

 The filtered cultures had less action. The toxin, therefore, mostly 

 lies in the bacilli (the same is true for influenza bacilli Kolle and 

 Delias). 



After an attack immunity only occurs to a limited extent. Morax 

 and Petit, L. Muller, Usher, and Fraser have several times observed 

 repeated attacks in the same individual within a short period of time. 

 AVeichselbaum and Miiller inoculated an individual four weeks after 

 recovery from a former inoculation conjunctivitis, and again got a 

 positive result. In spite of this, we cannot exclude the possibility of 

 some degree of immunity after an attack, 1 and, further, such a sup- 

 position most readily accounts for the subsidence of an epidemic. 

 The continued presence of virulent organisms on a practically healthy 

 conjunctiva for a long time after the inflammatory reaction has ceased 

 also favours this view. L. Muller reported a case favouring the per- 

 sistent presence of Koch- Weeks bacilli on the healthy conjunctiva 

 after an inflammation had subsided, and several months of perfect 

 health had ensued ; no reinfection could have occurred in the case, 

 and he considered it due to a relapse. 



Miiller also quotes that in himself an attenuated virus produced no 

 conjunctivitis, but that it caused a conjunctivitis of only one day's 

 duration in another individual. 



That susceptibility varies is shown by the fact that a very slight 



1 For the related disease influenza such a condition is affirmed by many (Baumler, 

 Wassermann, Clemens, Parsons, etc.), although it cannot be produced in animals (Kolle 

 and Doenitx). 



102 



