Serological Evidence on the European Type of Typhus Fever in China

Fletcher and Lesslar described what they called tropical typhus from the Federated Malay States. By using several strains of B. proteus × for the Weil-Felix test they showed that, though clinically the same, urban cases gave a positive agglutination with the X19 (Warsaw) strain while those from rural districts gave positive tests only with the Kingsbury strain. Spencer and Maxcy using the variants of X19, X2, and Xk (Kingsbury) found that the sera of patients with endemic typhus invariably agglutinated to a high titre the X19 strain, but possessed no appreciable group agglutinins for other strains. With Rocky Mountain spotted fever, however, X19 organisms were agglutinated significantly only in a minority of cases and to a lower titre than in endemic typhus; moreover, agglutinins for X2 and Xk were also found in a considerable proportion of these cases. Felix and Rhodes have recently studied more extensively the sera of patients with typhus and typhus-like diseases from various parts of the world and confirmed the above findings. There seems no doubt that some endemic diseases clinically simulating typhus give positive Weil-Felix reactions with the Xk strain to high or low titres, but not with the usual X19 strain, while still others give negative tests with any known strain. Felix and Rhodes propose to consider the various forms of typhus and typhus-like diseases as serological types of typhus. According to them the typhus nature of those diseases which give negative Weil-Felix reactions but otherwise are typhus-like may later be proved when corresponding types or variants of B. proteus × are isolated.