294 A MANUAL OF BACTERIOLOGY 



been found to carry the meningococcus. The duration of 

 the carrier state is uncertain ; a majority clears in from 

 two to three weeks, but others may persist for ten weeks 

 or longer, and all treatments seem more or less unsatis- 

 factory. The proportion of carriers who become cases of 

 cerebro -spinal fever is not known, but a considerable 

 number escape. While the presence of the meningococcus 

 in the nasopharynx suggests that infection of the meninges 

 is derived from this source via the cribriform plate of the 

 ethmoid, this is not generally accepted, and infection 

 is usually regarded as being conveyed by the blood- 

 stream. 



Anti-Serum and Vaccine. Flexner first prepared an 

 anti-serum by the injection of horses with cultures. The 

 method of preparation recently employed at the Rocke- 

 feller Institute consists in beginning with small and 

 increasing doses of living meningococci injected intra- 

 venously daily for three days, followed by a period of rest 

 of seven days. A second, and sometimes a third, series of 

 similar injections with increased amounts are given. Then 

 another strain is taken, and the same procedure is adopted, 

 and in this way a polyvalent serum for three or four strains 

 may be prepared in nine to twelve weeks. 



In some instances the anti-meningococcal serum has 

 been found very beneficial, markedly reducing the mor- 

 tality ; in others little or no result has followed its use. 

 This difference probably depends on whether the serum is 

 strictly homologous for the infecting organism or no. 

 The serum should be given intrathecally. Vaccine 

 treatment has also been tried in doses of 25 to 100 

 millions to commence with, but the general experience is 

 not favourable. 



Vaccine has also been used for prophylaxis, dose 50 to 

 150 millions intravenously. Sufficient data as to its value 

 are not available. 



