(615) Critical Clues in a Pediatric Case of Rocky Mountain Spotted Fever With Severe Complications

Introduction: Rocky Mountain Spotted Fever (RMSF) is a tick-borne illness caused by Rickettsia rickettsii, known for its diverse presentations and high fatality rate. Traditionally associated with specific US geographic regions, the disease epidemiology has been expanding. Subsequently, early treatment with doxycycline based on a high clinical index of suspicion, prior to confirmatory testing, has been advocated for by the CDC. We present a case of fatal RMSF in a 17-year-old female who presented with nonspecific symptoms of fever, myalgias, and multisystem inflammatory signs, which diverted initial management towards a presumptive diagnosis of multisystem inflammatory syndrome in children (MIS-C).

Description: Our previously healthy patient presented with headaches and myalgias and was admitted to the pediatric ICU in culture-negative septic shock, necessitating vasoactive support and broad-spectrum antibiotics. On hospital day 3, she had a rapid neurological decline, requiring intubation and mechanical ventilation. As she developed multi-organ dysfunction, she met criteria for a presumptive diagnosis of MIS-C and showed transient improvement after receiving IVIG. However, in the following 2 days she developed a petechial rash on her wrists. Further history revealed recent exposure to dogs and travel to Northern Mexico. This prompted additional testing, which confirmed Rickettsia rickettsii through cell-free DNA sequencing and antibody testing. Within one week of admission, she developed diffuse cerebral edema with cerebellar tonsillar herniation and succumbed to brain death shortly thereafter.

Discussion: The significance of this case lies in its demonstration of RMSF's ability to mimic other multisystem inflammatory conditions, such as MIS-C, which can distract from the underlying diagnosis. The critical clue came from her recent travel history to a region now recognized for recent RMSF outbreaks. A current review of the literature reveals a growing recognition of RMSF's varied presentations and an increasing number of cases outside documented endemic regions. This case underscores the need for heightened clinical vigilance and communication between public health departments and clinicians. Our case was likely among the 3 US fatalities mentioned in the CDC press release in December 2023.