[Unexplained fever after exposure to rats: rat bite fever or Haverhill fever].

A 24-year old man presented himself to the emergency ward with complaints of fever, nausea, headache, muscle ache and chest pain. Two weeks before presentation he had been bitten by a pet rat. We determined that he had bacteraemia caused by a Streptobacillus moniliformis infection, which led to the development of an illness called rat bite fever. S. moniliformis is a pleomorphic gram-negative rod-shaped bacterium that is considered part of the normal nasopharyngeal flora in rats. It is the cause of two similar illnesses: rat bite fever and Haverhill fever. Clinicians should consider these infections in the work-up of unexplained fever or sepsis, certainly in the presence of known exposure to rats. Treatment consists of antibiotics.