248 EPIDEMIC CEREBROSPINAL MENINGITIS 



Experimental inoculation shows that the ordinary laboratory animals 

 are relatively insusceptible to this organism. An inflammatory condition 

 may be produced in mice and guinea-pigs by intra-peritoneal injection, 

 and a fatal result with symptoms of collapse may follow ; in such cases 

 the organism does not seem to undergo very active multiplication, though 

 it may sometimes be cultivated from the blood, and none of the lesions in 

 the nervous system are reproduced. Similar results are produced by the 

 endotoxin in dead cultures, and occasionally the lethal dose of the dead 

 organisms may equal that of the living (Gordon). There is thus evidence 

 that an active endotoxin plays an important part in the pathology of the 

 disease. Flexner and also Stuart M 'Donald have shown that cerebro- 

 spinal meningitis may be produced in monkeys by injections of the 

 organism into the spinal canal, the latter observer finding that exudate 

 containing meningococci was more effective than cultures. In such 

 experiments the organism extends upwards to the brain, and produces 

 meningitis within a very short time. The resulting lesions, both as 

 regards their distribution and general characters, and also as regards the 

 histological changes, resemble the disease in the human subject. Even 

 these animals, however, are manifestly less susceptible than the human 

 subject. 



The meningococcus can usually be found in the naso-pharynx 

 of patients suffering from the disease, and there is no doubt that 

 this is the usual channel of infection. In cases where recovery 

 occurs, the organism may persist for a varying period of time, — 

 usually only for a week or two, but sometimes for months. 

 There is difference of opinion as to the route by which the 

 organism passes from the naso-pharynx to the meninges. One 

 view is that it passes directly by the lymphatics to the base of 

 the brain, but satisfactory evidence of this is wanting. The 

 other view is that it passes by the blood stream; this is in 

 accordance with what occurs in other infections, and is also 

 supported by the fact that in some very acute cases with 

 purpuric eruption, it has been found in the blood before 

 meningeal symptoms have appeared, and also occasionally in 

 septicaemic types without meningitis. For a considerable time 

 it has been known that contacts with cases of cerebro-spinal fever 

 often harbour the meningococcus in the naso-pharynx, that is, 

 are "carriers," and during the war this subject has been 

 extensively investigated. In fact, the examination of contacts 

 has become a routine procedure. The percentage of '' positives " 

 amongst contacts varies ; sometimes it has been found to be 

 twenty or even higher. Non-contacts also have been examined 

 during epidemics, and amongst them also a considerable propor- 

 tion, though not so great as amongst contacts, have been found 

 to be carriers. In some carriers the organism occurs sparsely 

 amongst other organisms, but in others in fairly large propor- 

 tion, and occasionally in almost pure culture. In the great 



