THE PARATYPHOID GROUP 349 



efficiency of refrigeration of meats in the warmer months. The incu- 

 bation period may be as brief as four to six hours, or as long as twenty- 

 four to seventy-two hours after ingestion of the infected food. The 

 initial symptoms are usually a severe headache and chill, rapidly 

 followed by acute gastro-intestinal disturbances, dizziness, nausea 

 and vomiting, abdominal pain and diarrhea. Nervous symptoms and 

 marked restlessness are characteristic of the severe and fatal cases. 

 Usually the symptoms and fever abate within a week; they may 

 persist for several weeks. The mortality is, as a rule, low, averaging 

 from 1 to 2 per cent. The conspicuous lesion observed at autopsy 

 is an intense hyperemia of the gastro-intestinal mucosa, usually with- 

 out noteworthy involvement of Peyer's patches. Fatty degeneration 

 of the liver is common. Bacilli (usually B. enteritidis or B. cholerae 

 suis, 1 less commonly B. paratyphosus beta) may be isolated from the 

 feces and blood stream in many of the acute cases during the first 

 few days of the disease. They are almost invariably recovered from 

 the heart blood and spleen at autopsy. Serum reactions, especially 

 specific agglutinins, may be demonstrated at the end of the first week 

 in many but not all cases. 



An epidemic of meat poisoning is characterized by the sudden, prac- 

 tically simultaneous onset of symptoms in those who have eaten the 

 contaminated food, and the limitation of the disease to the primary 

 cases. Secondary infection is uncommon. It should be remembered 

 that not all epidemics of meat poisoning are caused by members of 

 the paratyphoid group of bacteria. 



Distribution of Organisms. The hog cholera bacillus (B. cholera? 

 suis, B. suipestifer) is frequently found in the intestinal tracts of 

 swine, rats and mice; probably somewhat less commonly in cattle. 

 B. enteritidis is a frequent inhabitant of the intestinal contents of 

 rats and mice, and relatively uncommon in healthy cattle. 2 It is 

 suspected that a postmortem infection of beef is more common than 

 an antemortem invasion; this is reasonably suggested by the wide 

 distribution of rats and mice in slaughter houses. The organisms 

 possess the somewhat unusual property of rapidly diffusing them- 

 selves through the substance of meat after they have been distributed 

 on the surface of it by careless handling. Unless infected meat is 

 thoroughly cooked, the organisms are not killed, and they may not 

 be even weakened if the degree of heat and time of exposure is insuffi- 



1 Bainbridge, Lancet, March 16, 23, 30, 1912. 



2 Ibid. 



