This is a previously healthy 41-year-old man who presented with fevers, headache, and neck stiffness for 5 days. He also reported photophobia, anorexia, insomnia, nausea but no vomiting. He denied any recent travel and was not aware of any insect bites. The patient had a faint macular rash on his upper chest and abdomen, was febrile to 39°C, with HR 86, RR 24, and O2 sat 96% on room air. There was prominent neck stiffness but no focal neurological deficit. Lumbar puncture showed 9 nucleated cells with monocytic predominance, glucose of 61 and protein of 28. WBC 8,000 with bandemia of 53%, platelets of 117, elevated creatinine of 1.37, AST 63, ALT 96. Chest radiograph was normal and abdominal ultrasound demonstrated fatty liver and splenomegaly.
The patient was started on empiric acyclovir for suspected viral meningitis, which was discontinued on day 4 due to a negative HSV PCR. Doxycycline for suspected murine typhus was initiated despite initially negative IgM/IgG titers (<1:64).
On hospital day 2, the patient still had a fever of 41.3°C and developed hypoxemic respiratory failure requiring high-flow supplemental oxygen. Serial chest radiographs showed bilateral pulmonary opacities consistent with acute respiratory distress syndrome (ARDS). PaO2/FiO2 was 125 consistent with moderate ARDS. Echocardiogram showed normal EF, BNP of 50. Aggressive respiratory treatments were initiated: providing high flow oxygen, BIPAP as well as diuresis.
On day 3, the patient began to improve as he was requiring less supplemental oxygen, headaches subsided, and he became afebrile. On the day 6, day of discharge, repeat serologies demonstrated a 4-fold increase in Typhus IgG (1:256) and 8-fold increase of IgM (1:512) titers. He was discharged to finish a course of doxycycline.
Discussion:
Murine (endemic) typhus is a flea-borne disease caused by Rickettsia typhi. It is commonly under diagnosed because of its non-specific clinical findings, early phase false negative serologies, and is therefore prematurely labeled as a viral illness. Although murine typhus usually follows a benign course, pulmonary involvement can be life threatening. Symptoms can be as mild as a cough or dyspnea to severe and life-threatening ARDS requiring intubation. It is suggested that the severe manifestations are due to damaged pulmonary microcirculation leading to pulmonary capillary leak and ultimately ARDS.
Conclusions:
Murine typhus is frequently encountered by hospitalists, especially in Southern California. It is frequently under recognized; therefore a high level of suspicion should be entertained in anyone with malaise, fevers, headache and rash. Pulmonary involvement in murine typhus is also underreported and can range from mild symptoms to ARDS. Murine typhus should be considered in the differential diagnosis for idiopathic ARDS. It should be emphasized that pulmonary involvement may require higher level of care. An early initiation of anti-rickettsial antibiotics may prevent worsening respiratory status.