MICROBIAL DISEASES OF MAN AND DOMESTIC ANIMALS 747 



local lowered resistance occur. The prevention of this may be accom- 

 plished by strict antiseptic treatment of wounds. 



Pneumonia* 



Streptococcus pneumonicB 



The occurrence of a diplococcus in the large majority of cases, 

 especially of the lobar type of pneumonia, has caused this coccus to be 

 regarded as practically specific and warrants the name of Micrococcus 

 pneumonia, Diplococcus pneumoniae, or Pneumococcus. As occasional 

 causes of pneumonia should be mentioned Streptococcus pyogenes, 

 Staphylococcus pyogenes var. aureus, B. coli. Bad. diphtherice, Bact. 

 influenzce, B. capsulatus mucosus (pneumobacillus), B. typhosus 

 and Bact. tuberculosis. 



Pneumonia is world-wide in its distribution and is estimated to 

 form anywhere from i to 7 per cent of all cases studied in internal 

 medicine. It appears to be more frequent in regions subjected to 

 sudden changes of temperature. 



The incubation period is two or three days 6f rather indefinite 

 prodromata. 



The onset of the disease is marked by a chill, pain in the side, and 

 rise in temperature. The respirations become frequent. The fever, 

 as a rule, runs between 102° and io5°F. for from five to ten days and 

 then in favorable cases terminates by a sudden drop of temperature 

 to normal within a few hours (crisis). 



The most striking pathological findings are a marked congestion 

 and oedema of the lungs following which the lung becomes solid, 

 airless and of a dark red color, the alveoli showing, microscopically, 

 a fibrinous exudate with large numbers of red blood cells, some leucocytes 

 and desquamated epithelium. Thereafter the lung becomes slightly 

 softer and is of a gray color, while microscopically the red cells degener- 

 ate and leucocytes are more frequent and more evident. The final 

 stage, resolution, is marked by the liquefaction and absorption of the 

 contents of the alveoli and the entrance of air. 



Death occurs from toxasmia or complications such as carditis, men- 

 ingitis, etc. Roughly about 10 per cent of all deaths are due to pneu- 



* Prepared by Edward Fidlar. 



