An 80-year-old man with psoriasis on ustekinumab and type 2 diabetes mellitus (A1c 5.9) presented with seven days of fever. Two weeks prior to presentation, he underwent epidural steroid injection to the cervical spine for treatment of chronic neck pain. One week later, he developed fever to 103 °F. The patient had recently been in contact with a flea-ridden dog. He also reported a mouse infestation in his house, for which he had been trapping and disposing of the dead carcasses himself. He denied headache, neck stiffness, cough, diarrhea, dysuria, or a new rash. Physical examination was unremarkable. Complete blood count was notable for a white blood cell count of 14,600 cells/microliter and a platelet count of 145,000 cells/microliter. Liver function tests revealed an alanine aminotransferase (ALT) of 95 IU/L and aspartate aminotransferase (AST) of 110 IU/L. The patient was started on empiric vancomycin and ceftriaxone. Blood and urine cultures remained without growth. CT with contrast of the cervical spine did not show evidence of an epidural abscess. Despite broad spectrum antibiotics, the patient’s fever curve remained unchanged. Given his exposure history, Rickettsia typhi serologies were sent and the patient was started on empiric doxycycline, with rapid improvement in his fever curve and resolution of his lab abnormalities. He was discharged to complete a seven-day course of doxycycline. R. typhi IgG returned positive at a titer of 1:64, confirming the diagnosis of murine typhus infection.
Discussion:
Murine typhus is often overlooked by practitioners given the non-specific presentation of this disease entity. While murine typhus is described in tropical regions, within the United States up to 21 and 72 cases are reported annually in southern California and Texas, respectively. Murine typhus is spread by rat, mouse, and cat fleas with rats, domesticated cats, and opossums serving as hosts. Patients present with fever but may also report headache, arthralgias, or a maculopapular rash. Lab abnormalities may include leukocytosis, leukopenia, or transaminitis. In this patient, murine typhus was considered from the time of presentation. However, given his immunocompromised state and recent epidural steroid injection, a thorough investigation to rule out other sources of infection was completed. The patient’s rapid defervescence on doxycycline increased suspicion for murine typhus infection, which was diagnosed after discharge based on elevated titers of R. typhi IgG.
Conclusions:
This case highlights the importance of considering murine typhus in patients presenting with fever and either recent travel to a tropical region or residence in southern California or Texas. Patients with suspected murine typhus should be started on appropriate antibiotics without delay while waiting for R. typhi serologies.