140 AIDS TO BACTERIOLOGY 



from the meningococcus, and the probability of the 

 disease in man being derived from animal sources does 

 not appear to be likely. Cerebro-spinal meningitis more 

 often affects country districts than cities (Osier). It 

 arises under cold atmospheric conditions and disappears 

 with the advent of warm weather. Overcrowding, bad 

 sanitation, and privation are cited as predisposing 

 causes. 



In the body the meningococcus has primary residence 

 in the naso-pharynx. While it is there the host is a 

 carrier case, often without developing the disease himself. 

 Though carriers are usually free from the meningococcus 

 in two or three weeks, it persists in a small percentage 

 for two or even seven months. Mayer reported a case 

 probably existing two years. Carriers may develop 

 meningitis after two or three weeks. There is consider- 

 able variation in the number of carriers among contacts 

 in different epidemics. Among 300 soldiers who were 

 contacts Arkwright only found four carriers. In other 

 epidemics as many as 23 per cent, to 37 per cent, have 

 been reported. 



During the stay in the naso-pharynx, whether the host 

 be a healthy carrier or in the incubation stage of the disease, 

 the small drops of secretion expelled during sneezing, 

 coughing, or speaking serve to carry and disseminate the 

 meningococcus. Halliday Sutherland says that infection 

 is carried by currents of warm moving air. Kissing is 

 obviously dangerous. In the developed disease the 

 meningococcus is found in the cerebro- spinal fluid and 

 very often in the blood. 



Where a case is definitely attacked, the cerebro-spinal 

 fluid obtained by lumbar puncture shows distinctive 

 features: an increase of pressure, increase in albumin 

 content, and a polymorphonuclear leucocytosis frequently 

 so marked as to render the fluid quite turbid. An examin- 

 ation of the centrifuged deposit shows the meningococci 

 which are often within the leucocytes. If no diplococci 

 are found, recourse must be had to culture, but even then 

 negative results are sometimes obtained when all the 

 other evidence suggests meningococcal activity. Carrier 

 cases are detected by bacteriological examination of the 

 naso-pharyngeal secretion. As several non- or feebly- 

 pathogenic micro-organisms closely resembling the 



