Introduction

Rat bite fever (RBF) is a rare zoonosis caused worldwide by Streptobacillus monoliformis with Spirillum minus cases restricted to Asia.1 Transmission arises mainly by scratches or bites from colonised rats.1 At-risk groups include veterinarians, sewerage and laboratory workers or rat owners.1 Patients typically present within 7 days of exposure with an acute febrile illness characterised by headache, myalgia, migratory polyarthralgia and a rash.2 In the UK, one–two cases are diagnosed per year3 predominantly caused by S monoliformis.2 It is likely underdiagnosed due to a wide differential diagnosis and low culture sensitivity.2 If not suspected and treated with an appropriate antibiotic such as penicillin, mortality may reach 13%.1