Nonnegligible Seroprevalence and Predictors of Murine Typhus, Japan

Abstract

To elucidate the epidemiology of murine typhus, which is infrequently reported in Japan, we conducted a cross-sectional study involving 2,382 residents of rickettsiosis-endemic areas in Honshu Island during August-November 2020. Rickettsia typhi seroprevalence rate was higher than that of Orientia tsutsugamushi, indicating that murine typhus is a neglected disease.

Keywords: Japan; Japanese spotted fever; Orientia tsutsugamushi; Rickettsia japonica; Rickettsia typhi; bacteria; cross-sectional studies; flea borne; murine typhus; rickettsia; scrub typhus; seroepidemiological studies; spotted fever group rickettsiosis; typhus; vector-borne infections.

Figure 1

Seroprevalence rates of Rickettsia typhi and Orientia tsutsugamushi in study of seroprevalence and predictors of murine typhus, Japan. R. typhi IgG was detected in 11.3% (95% CI 10.0–12.6) of participants and O. tsutsugamushi IgG was detected in 7.9% (95% CI 6.9–9.1) of all participants. The seroprevalence of both infections was compared using the McNemar test. The estimated seropositivity ratio was 1.42 (95% CI 1.20–1.68).

Figure 2

Predictors of Rickettsia typhi IgG seropositivity in study of seroprevalence and predictors of murine typhus, Japan. Shown are adjusted odds ratios for age per 10-year increase; population density increase; residential geographic features, such as coasts, forests, farmland, and rivers and lakes; and wilderness per 10-hectare increase. Bushes refer to areas with small trees and weeds.