Rat bite fever on Vancouver Island: 2010-2016

Background: Rat bite fever (RBF) is a rare bacterial zoonotic infection caused by Streptobacillus moniliformis and Spirillum minus, which are found naturally in rodent respiratory tracts. Recently, multiple cases of RBF were observed on Vancouver Island, British Columbia.

Objective: To conduct a case series analysis of cases of RBF on Vancouver Island between 2010 and 2016 to characterize the epidemiology, presentation, microbiology and treatment of RBF.

Methods: Cases were identified through queries of discharge diagnosis and microbiology laboratory information. Clinical details were collected through review of electronic and paper chart reviews of hospital documentation from Island Health.

Results: Eleven cases of RBF on Vancouver Island were identified between 2010 and 2016. Most cases of RBF were confirmed with identification of S. moniliformis by culture or molecular techniques. All cases presented with fever, and a subset had one or more of the following: myalgia, rash, polyarthralgia, joint effusions, and emesis. All cases were successfully treated with penicillin, ceftriaxone or doxycycline. Seven cases required hospitalization, but there were no deaths or significant morbidity.

Conclusion: This is the largest single case series of RBF in Canada. Diagnosis requires a high index of suspicion by clinicians and early intervention is necessary to prevent morbidity and mortality.