SESSION TITLE: Infectious Disease Cases II
SESSION TYPE: Affiliate Case Report Slide
PRESENTED ON: Wednesday, October 28, 2015 at 11:00 AM - 12:15 PM
INTRODUCTION: Murine typhus is caused by a small gram-negative obligate, intracellular bacterium. In the mid 1940’s, over 5000 cases were reported annually, but with eradication of flea vector this has reduced dramatically. Upon entry into the host this bacterium parasitizes the endothelial cells proliferating causing vasculitis, ischemia, and thrombus formation leading to multi-organ dysfunction. Confirmation with serology may take too long, therefore the clinical decision to treat should be made based on the patient’s presentation which at times can be very non-specific and misleading. Though lung involvement is uncommon, this can present with pulmonary infiltrates, edema, and rarely as acute respiratory distress syndrome (ARDS) leading to respiratory failure. Early clinical recognition and treatment of murine typhus is very important, as death is a very rare complication upon prompt initiation of appropriate antibiotics.
CASE PRESENTATION: A 40-year-old male presented with fevers, and epigastric pain for one week. Physical exam revealed a maculopapular rash on the chest, and upper extremities. Given that the patient worked as an animal groomer, he was started on empiric doxycycline for suspected rickettsiosis. On hospital day two, the patient developed hypoxic respiratory failure, with computed tomography demonstrating biapical pulmonary infiltrates and a small right-sided pulmonary effusion. His respiratory failure gradually improved and serologies later confirmed the diagnosis of murine typhus after his discharge home.
DISCUSSION: Endothelial injury is the key element in the pathogenicity of endemic typhus. Murine typhus pneumonitis is thought to be secondary to capillary leak as a result of the endothelial damage. While rare, lung involvement can present as pulmonary infiltrates, edema, pleural effusion and even more rarely as ARDS. One review article discovered a prevalence rate of cough and abnormal chest radiographs to be around 30% and 16%, respectively. Among the 1,060 patients in the review, only two fatalities were reported, both associated with severe disease complicated by ARDS.
CONCLUSIONS: While rare, murine typhus can be complicated by potentially fatal respiratory failure. Therefore the initiation of treatment should be based upon index of suspicion, paying particular attention to any patient presenting with fever of unclear etiology with exposure to cats, opossums, and their fleas.
Reference #1: Van der Vaart TW et al. Emerg Infect Dis. 2014;20(8):1375-1377.
Reference #2: Civen R, Ngo V. Clin Infect Dis. 2008;46:913-918.
DISCLOSURE: The following authors have nothing to disclose: Sharareh Shahangian, Jennifer Fu, Janine Vintch
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