788 MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC ANIMALS 



The incubation period is unknown. 



There is considerable variety in the character of the cases. As a 

 rule the invasion is sudden with headache and vomiting as prominent 

 symptoms. The headache usually increases, with disturbances of 

 vision, restlessness, and pains and rigidity in the muscles of the back 

 and neck. The temperature is irregular and variable, the usual being 

 about 101 to 102. Herpes occurs frequently and a purpuric rash is 

 common, especially in the severe cases, so that the term "spotted fever" 

 has sometimes been given to the disease. The patient usually passes 

 into a stuporous state, though delirium may occur before it. Death 

 may occur in a few hours (fulminant type) or within a week, or occa- 

 sionally may be postponed as late as six months. In all favorable 

 cases the recovery is slow. 



A fibrinous exudate which occurs chiefly at the base of the brain, 

 and the presence of pus cells in the cerebro-spinal fluid, are prominent 

 pathological features, but in the fulminant cases the gross pathological 

 findings may be surprisingly insignificant. 



According to Flexner, serum treatment has reduced the mortality 

 of the disease from about 70 per cent to 30 per cent, and to less than 

 20 per cent if treatment is begun within the first three days. 



The demonstration of the organism in the cerebro-spinal fluid of 

 the typical case may sometimes be an easy matter, but at other times 

 may require a prolonged search. It appears as a Gram-negative coccus, 

 single and in pairs, frequently within pus cells but occasionally extra- 

 cellular. From the usual case it can be obtained in pure culture by 

 sowing the sediment from the spinal fluid upon suitable media. The 

 amount of material planted should be abundant and to supplement 

 these first cultures it is well to incubate the fluid at 37 for twelve to 

 eighteen hours and then make further inoculations. The media used 

 are often blood agar or serum glucose agar, but legumin-trypagar was 

 most successful in the British army during the war. 



As found in culture media the meningococcus will show swollen 

 involution forms often in comparatively young cultures. There are no 

 spores, flagella nor capsules. It can be stained readily by the aniline 

 dyes and with methylene blue will sometimes show metachromatism. 

 It is Gram-negative. 



The temperature relations are of some importance in identifying 

 the coccus. It has a minimum temperature of about 25, an opti- 



