Diagnosing and reintegrating traceability of infectious diseases via metagenomic next-generation sequencing: Study of a severe case of Rickettsia japonica infection

In this study, we present a case of Japanese spotted fever (JSF) caused by Rickettsia japonica and use this case to investigate the process of diagnosing and reintegrating traceability of infectious diseases via metagenomic next-generation sequencing (mNGS). From data relating to epidemiological history, clinical and laboratory examinations, and mNGS sequencing, a diagnosis of severe JSF was concluded. A detailed field epidemiological investigation discovered parasitic Haemaphysalis longicornis from a host animal (dog) in the domicile of the patient, within which R. japonica was detected, along with a diverse array of other potentially pathogenic microorganisms that could cause other infectious diseases. The mNGS provided an efficient method to diagnose JSF infection. This methodology could also be applied to field epidemiological investigations to establish the traceability of infectious diseases.