MICROBIAL DISEASES OF MAN AND ANIMALS. 641 



characteristic histological feature is the crowding of the lymph spaces 

 by proliferated endothelial cells. 



Perforation and hemorrhage of the bowel, peritonitis, myocarditis, 

 thrombosis, etc., render typhoid fever a dangerous disease. The fatality 

 varies considerably; at one time estimated at 25 per cent, it has been 

 brought down to 10 to 15 per cent by modern methods of treatment and 

 has been given in Minnesota as low as 4 per cent. 



Eberth found the organism in 1880 by the examination of the mesen- 

 teric glands and spleen of fatal cases. Gaffky cultivated it in 1884. 

 The causal relationship has been a matter of gradual acceptance through 

 evidence furnished by the study of such immunity processes as agglutina- 

 tion, bacteriolysis, and complement deviation, and finally by the high 

 percentage of positive blood cultures. Conclusive evidence is afforded 

 by the development of typhoid fever following the ingestion of pure 

 cultures with suicidal intent. 



The agglutination reaction of Gruber and Widal is universally em- 

 ployed in diagnostic laboratories. The blood serum of typhoid patients, 

 after a certain period of the disease, will cause a characteristic clumping 

 of the bacilli when mixed with pure cultures. The fresh serum from a 

 clot may be used, or, more conveniently, dried blood from which a watery 

 extract can be made. In positive cases the reaction is present in at least 

 the one-fiftieth dilution and usually in the one-hundredth or higher dilu- 

 tions. The culture employed should be 18 to 24 hours old; it should be 

 freely agglutinable and show no artificial clumping, characters not 

 possessed by all strains, especially those recently isolated. Cultures 

 killed by a small percentage of carbolic acid have been recommended 

 for constancy in place of the living organisms. When the microscopic 

 method is used the reaction should be distinct in about one hour. 



An immune body capable of binding complement in the presence of 

 typhoid antigen is said to occur in typhoid sera before the agglutinative 

 property appears. 



The detection of the typhoid bacillus in the circulating blood has 

 recently been very widely successful and furnishes the best support for 

 the diagnosis of the disease. While blood culture may be hardly practical 

 in public health laboratories, it has become a routine measure in the 

 modern hospital. Blood is taken aseptically from a vein and about i to 

 5 c.c. is introduced into culture media, of which fluid media containing 

 ox-bile and agar plating media containing glucose have been most strongly 

 41 



