The incidence and significance of Phase 1 complement-fixing antibody in Q fever

Abstract

1. An attempt has been made to follow up a consecutive series of seventy-two patients for the presence of Phase 1 C.F. antibody approximately 2 years or more after the acute illness. Fifty-one of the series were tested.2. Fifteen of the fifty-one patients had detectable amounts of antibody, generally in low titre.3. The presence of Phase 1 antibody correlated well, in older age-groups, with the duration of convalescence following the acute illness. There was no correlation with the duration of fever.4. All cases with Phase 1 antibody also had Phase 2 antibody, usually in slightly higher titre. In no case in which Phase 2 antibody was absent or present in low titre was Phase 1 antibody found.5. It is suggested that the presence of Phase 1 C.F. antibody is an indication of past persistent infection. It cannot necessarily be concluded that it is an indication of present persisting infection.We wish to thank Dr H. Silverstone, Senior Lecturer in Medical Statistics, University of Queensland, for statistical advice.