A Study of the Complement Fixation and Weil-Felix Reactions in Wild Rats as Related to the Isolation of the Virus of Endemic Typhus

Abstract

The complement-fixation, Weil-Felix, and virus-isolation tests were compared as a means for the diagnosis of endemic typhus fever in experimentally infected white rats and naturally infected wild rats. In the white rats the correlation between the complement-fixation and virus-isolation tests was 100% insofar as tested, i.e., to 6 months following infection. Among wild rats from infected areas, the complement-fixa- tion test showed a large % of positive results. However, in this instance, correlation between the complement-fixation and the virus-isolation results was poor since positive serol. findings apparently persisted much longer than transmissible virus. No titer range could be established as indicating present infection. In nontyphus areas the results of the complement-fixation test were uniformly negative. A positive Weil-Felix test apparently indicates a recent infection since the reaction in white rats experimentally infected disappeared between the 14th and 20th day following inoculation. However, accurate information on this point in regard to the wild rats was not obtained. In any case positive Weil-Felix reactions were infrequent among the rats in the areas studied. The complement-fixation reaction as applied to rat-control programs should be a valuable aid in preventing the spread of endemic typhus to man.