AVIDITY OF IGG TO RICKETTSIA PROWAZEKII AS AN ADDITIONAL CRITERION FOR THE SEROLOGICAL DIFFERENTIAL DIAGNOSIS OF THE EPIDEMIC TYPH AND ITS RECRUDESCENT FORM - BRILL-ZINSSER DISEASE

Abstract

Aim: to investigate the diagnostic significance of avidity index (AI) for IgG toR. prowazekii with the determination of specific G and M class antibodies. Materials and methods. IgG/IgM to R. prowazekii, their titers and AI of IgG were measured in ELISA in 112 serum samples (47 sera from typhus-vaccinated individuals and 65 samples from patients and/or convalescents of epidemic typhus and/or Brill-Zinsser disease, including 18 sera collected during Lipetsk epidemic typhus outbreak in 1998).Results. Methodological approaches for estimation of AI for IgG toR. prowazekii have been determined. The initial period (or acute) of epidemic typhus we serologically detected in 8 cases by identifying of IgM toR. prowazekii only in two sera and IgM as well as IgG toR. prowazekii with low or medium values of AI in 6 samples. In 19 samples from patients we indicated Brill-Zinsser disease due to the presence in them specific IgM and IgG to R. prowazekii with high values AI. In 2 sera from vaccinated persons was established a low AI of IgG at significant diagnostic titers. Conclusion. AI of IgG to R. prowazekii has high prognostic information for differential diagnosis of epidemic typhus and Brill-Zinsser disease.

Keywords

• rickettsia prowazekii
• rickettsia prowazekii
• avidity of antibodies
• specific igg and igm
• epidemic typhus
• brill-zinsser disease
• differential diagnosis