A 24-year-old uninsured previously healthy female, “Bianca” presented at the Laguna Beach Community Clinic with a chief complaint of a long-lasting fever that had been present for the past three weeks.
Medical history and review of symptoms were negative, especially for new exposures or travel. Her only medication was Orthotricyclen for contraception. She had made her sexual debut in the past six months with her fiance.
Temperature was 99°F, and other vital signs were within normal limits. Urine chorionic gonadotrophin and urine dipstick were negative. A full examination, including a pelvic exam was negative. The patient’s assessment was “viral syndrome.”
Bianca applied for the Family Planning Access Care and Treatment Program and routine STI testing was performed for gonorrhea, chlamydia, syphilis and HIV. All tests were negative. I also took and complete blood count, chemistry panel and monospot.
The patient was instructed to increase her oral fluids, take over the counter antipyretics as directed and return in two days.
That night, I received phone call from Bianca informing me that she had begun vomiting. I instructed her to go to the ED for evaluation. A computed tomography scan of the abdomen was normal, and she was discharged with a diagnosis of viral illness.
Bianca collapsed just before leaving the ER, became hypotensive and unresponsive. She was admitted to the ICU, intubated, placed on a ventilator and dopamine was initiated.
Pertinent laboratory results from the clinic included:
- Bili: 1.9 (0.1-1.5)
- Alk Phos: 146 (27-142)
- AST 202 (1-45)
- ALT 127 (1-55)
- WBC 3.0 (4.1-11.3)
- Platelet count 64 (150,000-400,000)
- Monospot negative
- GC/Chlamydia, HIV, RPR negative
All of the laboratory results were faxed to the hospital.
By the second day in the ICU, Bianca’s condition deteriorated to such an extent that the hospital called her parents on the East coast and advised them to come urgently.
The hospitalist treating Bianca consulted an infectious disease specialist, who recognized and accurately diagnosed murine typhus (see explanation below). The patient was immediately administered intravenous doxycycline 100 mg twice daily.
With her parents at the bedside, Bianca improved dramatically. By the end of her third day in the hospital, she was extubated and transferred to the floor. She eventually went home at the end of the fourth day.
A history taken later was significant for Bianca’s two dogs playing with a dead possum in her backyard. She admitted to hugging and kissing her dogs often.
What is murine typhus?
Murine typhus is an uncommon flea-borne infection caused by Rickettsia typhi. Humans can become infected with exposure to infective flea feces. In the United States, domestic cats and their fleas and opossums may harbor both R. typhi and R. felis, which are virtually indistinguishable.
The primary pathophysiological process of R. typhi infection is an inflammatory vasculitis manifested by perivascular infiltration of lymphocytes, macrophages, plasma and mast cells.
Murine typhus is underdiagnosed because of it’s nonspecific symptomatology, which is frequently mistaken for a viral illness. Furthermore, patients are unlikely to remember having had flea bites.
Clinical manifestations include fever, headache, chills and myalgias. Nonspecific gastrointestinal symptoms include nausea, vomiting, diarrhea and abdominal pain. A fine, maculopapular rash appears in some patients at the end of the first week of illness. Typically, it begins on the trunk, and spreads to the periphery without affecting palms and soles.
Laboratory findings include thrombocytopenia in up to 49% of infected patients, normal WBC, mild leukocytosis or leukopenia and abnormal liver function tests in 60% to 90% or patients.
Murine typhus treatment guidelines recommend initiating empiric treatment with doxycycline for nonpregnant adults or chloramphenicol in pregnant women. The diagnosis is confirmed with serology tests after the course of therapy is concluded. The mainstay of diagnosis is the indirect fluorescent antibody test, which is available through state health department laboratories.
Preventive measures include prompt removal of outside pet food, trimming vegetation and covering trashcans to discourage rats and opossums from yard areas.
Since most cases of murine typhus occur in Texas and California, it behooves nurse practitioners in these regions to have a higher index of suspicion for murine typhus in the setting of nonspecific febrile illness.
Karen Deck, MSN, NP-BC, is from San Juan Capistrano, Cali.
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