The Case for a Diagnosis of Possible Rickettsia felis in a Case Cluster in a Military Family

Dear Dr. Rothwell: We thank Drs. Blanton and Walker for their interest in our case report and for highlighting the need for better diagnostics and cooperation between medical providers, public health authorities, and pest managers. We would also like to thank you and your team for this opportunity to address the letter. We feel that all efforts to better understand the reemergence of flea-borne rickettsiosis will improve public health and, for our population of interest, maintain military readiness. To this end, when we found evidence that the pathogen in this case cluster could be Rickettsia felis, we felt it was a great opportunity to highlight to the military medical community the threat of flea-borne rickettsiosis and a potential undetected role of R. felis. We found it likely these cases resulted from R. felis because of several lines of evidence. First, the index patient had an eschar which is noted in 12% of flea-borne spotted fever although eschar is not associated with murine typhus except one single case report. This symptom may not have been apparent in our manuscript because of a typo in our case report section that should read: “Signs and symptoms included headache, eschar, bumps in his mouth, and a low-grade fever.” Unfortunately, polymerase chain reaction-based species-specific testing was not conducted on any human samples (especially an eschar biopsy on the index patient) in our case study because suitable samples had not been collected. This would have definitively ­confirmed a R. felis diagnosis, through the targeting of its specific genes including ompB that was sequenced in our study to confirm the presence of R. felis in multiple fleas collected from the master bedroom.