Rickettsia parkeri Proved Fatal in a Child With Profound Chemotherapy-Induced Immunosuppression
A 3-year-old boy receiving chemotherapy for high-risk B-cell acute lymphoblastic leukemia died in Georgia after a Rickettsia parkeri infection progressed from a localized eschar to overwhelming systemic illness. The case is unusual on several levels: this spotted fever rickettsiosis is generally mild to moderately severe, yet here it unfolded in a profoundly immunocompromised child with febrile neutropenia, rapid respiratory decline, shock, and cardiac arrest. Diagnosis arrived only after death had become unavoidable.
The clinical course shows how easily a tickborne infection can disappear inside a familiar oncology syndrome. Fever, pancytopenia, neutropenia, and concern for bacterial or fungal infection naturally drove treatment toward cefepime, then broader antibacterial, antifungal, and antiviral coverage. The tickborne diagnosis sat outside the usual frame until plasma microbial cell-free DNA sequencing and confirmatory pathology identified the organism.
Eschars on the Arm Were the First Clue
The child was admitted in late July 2025 from southwestern Georgia with febrile neutropenia during the second month of delayed intensification chemotherapy. His laboratory profile on arrival was severe: leukocyte count 110/µL, absolute neutrophil count 20/µL, and platelets 19,000/µL. Examination was otherwise unremarkable except for two pink papulonodules with central eschars on the left upper extremity. Those lesions had reportedly been present for about a month and had drained clear fluid. His parents believed they were insect bites because he played in grass around the family home. No tick or insect was ever seen.
That detail mattered clinically because R. parkeri classically produces fever, myalgias, headache, rash, and often an eschar at the bite site. In a child with intact immunity, the skin lesion would have been a prompt diagnostic clue. In this case, the same lesion blended into the background noise of neutropenic fever, where the first instinct is to cover gram-negative bacteria and then expand therapy if the fever persists.
On hospital day 1, cefepime was started after blood cultures were drawn. Fever persisted, cultures stayed negative, and the child remained pancytopenic with an unmeasurable lymphocyte count. Micafungin and acyclovir were added as concern grew for disseminated Candida infection or herpesvirus disease. PCR testing of an unroofed vesicle was negative for herpes simplex virus and varicella zoster virus.
Rash Expansion and Organ Dysfunction Followed Fast
By hospital days 2 and 3, the rash widened from the upper back and arms to numerous pink macules, some with overlying vesicles, eventually involving the face, trunk, and both upper and lower extremities. The distribution was more extensive than the scattered macules and vesicles usually described in R. parkeri rickettsiosis. The facial involvement and the pace of progression signaled a far more aggressive process than the classic presentation.
Imaging added evidence of systemic injury. Chest computed tomography with contrast showed minimal ground-glass opacities. Abdominal ultrasound found hepatomegaly, trace ascites, and thickened inflamed small-bowel loops consistent with neutropenic enteritis. By hospital day 7, hypotension and respiratory failure had developed, forcing transfer to the intensive care unit and bilevel positive airway pressure support.
The antimicrobial regimen expanded again to meropenem, vancomycin, amphotericin B, isavuconazole, and doxycycline. Even that breadth could not reverse the trajectory. The child worsened hemodynamically and became more hypoxic, then required intubation. During the procedure, he suffered a 20-minute cardiac arrest with chest compressions before return of spontaneous circulation. Fixed and dilated pupils followed. Life-sustaining therapy was withdrawn, and he died on hospital day 8.
Cell-Free DNA Sequencing and Tissue Pathology Confirmed the Diagnosis
The diagnostic turning point came after a plasma sample submitted on hospital day 7 returned positive for R. parkeri by microbial cell-free DNA sequencing, with 8,374 molecules per 100 nL. Confirmatory testing at the Centers for Disease Control and Prevention identified R. parkeri DNA by real-time PCR targeting a 96-bp segment of the ompB gene. Skin biopsy sections stained by immunoalkaline phosphatase showed abundant rickettsial antigen in vessel lumina, endothelium, and adjacent dermal tissue.
The pathology fits the organism’s biology. Spotted fever group rickettsiae are endothelial pathogens, and vascular infection explains the rash, capillary injury, and multisystem deterioration. In an immunocompetent host, cellular immune control limits spread. Here, profound lymphopenia from leukemia and chemotherapy likely removed a critical brake on intracellular replication. Experimental work has shown the importance of CD4 and CD8 T cells, with CD8 T-cell activity especially important for clearing rickettsial infection. The child’s immune deficit created the conditions for unchecked vascular invasion.
A second factor may have been inoculum burden. Mouse studies have shown lethality with high-dose R. parkeri exposure, supporting the possibility that a large infectious load can convert an ordinarily milder illness into a fatal one.
Why This Case Changes the Bedside Differential
Only one other immunocompromised R. parkeri case has been documented, in a kidney transplant recipient whose illness remained moderate and resolved with doxycycline. This child’s death widens the clinical concern. Febrile neutropenia often has an obvious explanatory framework, and standard protocols correctly prioritize broad gram-negative coverage. Yet in endemic regions, especially during summer months, an eschar should trigger consideration of spotted fever rickettsiosis even when the patient is already hospitalized for another reason.
The geography and season fit the transmission cycle. R. parkeri is carried by the Gulf Coast tick, Amblyomma maculatum, whose range includes southwestern Georgia. Adult ticks are most active in July and August, exactly when this child became ill. That overlap between ecology and oncology is the practical hazard: a vectorborne infection can begin as a minor-looking skin lesion and then be absorbed into the assumptions of cancer care.
Doxycycline remains the treatment of choice for all rickettsial infections, but recognition must come early enough for it to matter. Unbiased plasma cell-free DNA sequencing can help identify fastidious pathogens in patients whose symptoms do not fit a routine bacterial or fungal pattern, though send-out testing still costs time. In this case, time was the limiting factor, and the delay between presentation and organism identification was fatal.
For clinicians caring for immunocompromised children in tick-endemic regions, the message is concrete. Fever plus eschar deserves a spotted fever differential, even during neutropenia. In a host with collapsed cellular immunity, R. parkeri can behave less like a self-limited rickettsiosis and more like a fulminant endothelial infection capable of death.