THE PNEUMOCOCCUS 105 



The pneumococcus is closely allied to the streptococcus, 

 from which it is sometimes hard to distinguish. 



Four varieties of pneumococci are recognized, as fol- 

 lows : 



Type I, found in about 30 to 50 per cent, of all cases of 

 pneumonia, and has a mortality of about 25 per cent. 



Type II, found in from 15 to 40 per cent, of the cases 

 of pnuemonia, and has a mortality of about 60 per cent. 



Type III, also called the Pneumococcus mucosus, causes 

 from 5 to 15 per cent, of the cases of pneumonia, and has 

 a mortality of about 60 per cent. 



Type r\" is often found in normal throats. It causes 

 about 20 per cent, of the cases of pneumonia and has a 

 low mortality rate, from 5 to 10 per cent. 



Serum treatment appears to give the best results in 

 pneumonia due to Type I. 



When collecting specimens of sputum for laboratory 

 tests to determine the type of pneumococcus present, 

 care should be taken that the specimen is fresh, collected 

 in a sterile bottle without disinfectant, and sent at once to 

 the laboratory. 



The pneumococcus is responsible for most of the cases 

 of lobar pneumonia and for more than half of the other 

 forms of 1 neumonia. Other infections in which the pneu- 

 mococcus is frequently the causative agent are pleurisy, 

 otitis media, with its complicating mastoiditis, meningitis, 

 endocarditis (inflammation of the valves of the heart), 

 rhinitis (inflammation of the nasal passages), tonsillitis, 

 arthritis (inflammation of joints), conjunctivitis, and 

 keratitis (inflammation of the outer ('()\ering of the eye- 

 ball). 



Usually when the pneumococcus invades the lungs an 



