The Rickettsiae 389 



gut of the body louse, Pediciilus hunianus, and the head louse, 

 Pedicuhis capitis. Synonyms for the disease include Wolhynian 

 fever, shin bone fever, and five-day fever. 



The two other families, Bartonellaceae and Chlamydozoaceae, 

 listed under the order Rickettsiales will not be discussed. Inter- 

 ested students are invited to obtain further information on these 

 microorganisms from other textbooks in the field and from Bergey's 

 Manual. 



LABORATORY DIAGNOSTIC TECHNICS 



While most clinical laboratories are not equipped or staffed to 

 carry out extensive isolation and identification procedures with 

 respect to rickettsiae, there are serological tests available which 

 when correlated with the clinical findings will corroborate a diag- 

 nosis of disease of rickettsial origin. The diagnosis, however, is 

 primarily a clinical one. 



Weil and Felix in 1915 isolated a strain of the bacterium Pro- 

 teus vulgaris (designated OX 19) from a patient suffering from 

 typhus fever, and by employing a suspension of these bacterial 

 cells as antigen, the serum from typhus patients was found capable 

 of agglutinating the proteus cells. The so-called Weil-FelLx re- 

 action is based upon the production of antibodies (agglutinins) in 

 patients or in animals infected with typhus fever, but agglutinins 

 do not appear much before the tenth day of the disease. 



There is some antigenic fraction held in common by rickettsiae 

 and certain strains of proteus bacteria, although this gram nega- 

 tive rod is not found associated with all cases of typhus fever. 

 Two additional strains of these same bacteria have been found to 

 bear an antigenic relationship to rickettsiae, and these proteus 

 strains have been named OX 2 and OX K. Difi^erences in the 

 agglutinability of these three bacterial strains by the blood serum 

 of infected persons serves as a basis for separating rickettsiae as 

 will be seen in the table which follows. Strong agglutination re- 

 actions are given ratings of four plus, with lesser degrees of clump- 

 ing being indicated by fewer pluses. A plus-minus reaction means 

 it is doubtful. 



