| serological studies on human plague in southern africa. part i. plague antibody levels in a population during a quiescent and a subsequent active period in an endemic region. | yersinia pestis fraction l passive haemagglutination studies on human sera obtained randomly during a plague epidemic showed a 10-fold increase in occurrence of antibodies compared with the results obtained on sera from the same population 11 months earlier during a quiescent phase. the pre-epidemic population antibody rate was lower than that in a comparable population tested simultaneously in another endemic region, where a recrudescence of plague was not experienced during the following year. ... | 1975 | 1154171 |