Murine Typhus in Heart and Kidney Transplant Recipients: First Reported Cases Diagnosed by Microbial Cell-Free DNA Sequencing.

Murine typhus, caused by Rickettsia typhi, is a flea-borne illness that can present as an undifferentiated febrile syndrome and is often underrecognized in immunocompromised individuals. We report the first known cases in heart and kidney transplant recipients, both diagnosed using microbial cell-free DNA (mcfDNA) sequencing. The heart transplant patient presented with encephalopathy and hyponatremia, while the kidney transplant patient had fever and gastrointestinal symptoms. In both cases, mcfDNA sequencing enabled early detection of R. typhi prior to IgG seroconversion, allowing timely initiation of doxycycline and clinical recovery. These cases underscore the protean manifestations of murine typhus in solid organ transplant recipients and the utility of molecular diagnostics in this population. Clinicians should consider murine typhus in febrile transplant patients, especially those residing in or returning from endemic areas, to facilitate early recognition and appropriate treatment.