Clinical characteristics and outcomes of Rickettsia japonica infection: A retrospective case series of five patients

Abstract

Objective

To characterize the clinical manifestations of Rickettsia japonica (R. japonica) infection and to generate evidence facilitating early diagnosis and targeted treatment.

Methods

We retrospectively reviewed the clinical data of five patients with R. japonica infection who were treated in the Emergency Department, Xiling Campus, Yichang Central People's Hospital, between January 2023 and December 2024.

Results

All patients were residents of Yichang City, Hubei Province, aged 58–70 years, and 80% (4/5) were farmers. The onset of illness occurred exclusively between May and September, and all patients reported a definite history of outdoor exposure. The predominant clinical manifestations were fever, rash, and eschar. Laboratory findings revealed thrombocytopenia, elevated aspartate aminotransferase (AST) and creatine kinase (CK), as well as increased inflammatory markers including C-reactive protein (CRP), procalcitonin (PCT), and interleukin-6 (IL-6). R. japonica nucleic acid was detected in all patients by metagenomic next-generation sequencing (mNGS) of blood samples. Three patients initially received empirical doxycycline therapy, which was subsequently adjusted to a standard regimen after diagnostic confirmation. Defervescence occurred at a median of two days (range, 1–7 days), followed by gradual resolution of rash and alleviation of systemic symptoms. All patients achieved complete clinical recovery and were discharged without complications.

Conclusion

This study highlights the importance of heightened clinical awareness of R. japonica infection, emphasizing the integration of epidemiological context with hallmark clinical features – particularly fever, rash, and eschar – during peak transmission seasons in endemic areas. Early recognition allows the timely initiation of doxycycline therapy, which is essential for achieving favorable outcomes. Moreover, metagenomic next-generation sequencing (mNGS) provides the definitive identification of pathogens and guides targeted antimicrobial therapy.