Rare case of Rat Bite Fever reported in NEJM

Dr Stephane Giorgiutti and Dr Nicolas Lefebvre at Nouvel Hôpital Civil, Strasbourg, France have reported a rare case of Rat Bite Fever. The case has appeared in the New England Journal of Medicine.

Rat-bite fever (RBF) is an infectious disease caused by two different bacteria:

• Streptobacillus moniliformis, the only reported bacteria that causes RBF in North America (streptobacillary RBF)


• Spirillum minus, common in Asia (spirillary RBF, also known as sodoku)

People typically become infected with these bacteria after contact with rodents carrying the bacteria. Person-to-person transmission does not occur. According to CDC, the symptoms of Rat Bite Fever include Fever, Vomiting, Headache, Muscle pain, Joint pain or swelling (about 5 in 10 people with RBF have this), Rash (occurs in about 3 out of 4 people with RBF)

The symptoms usually begin 3 to 10 days after contact with the bacteria, but can be delayed as long as 3 weeks. By this time, any rodent bite or scratch wound that caused the infection has usually healed. Within 2 to 4 days after the fever begins, a rash may appear on the hands and feet. This rash looks like flat, reddened areas with small bumps. One or more joints may then become swollen, red, or painful. The symptoms that develop with Haverhill Fever (the type of infection that can follow after consuming contaminated food or water) are similar to Streptobacillary RBF but may include more severe vomiting and sore throat.

According to history, a previously healthy 36-year-old woman presented to the infectious diseases clinic with a 3-day history of fever, arthralgias, myalgias, and headache. She reported no recent travel or new sexual contacts. She stated that she had been bitten on her left hand by a pet rat approximately 10 days before the presentation. Physical examination revealed a maculopapular rash on the feet (Panel A) and hands (Panel B), with pustule formation (Panel C). The right ankle, left knee, and left wrist were swollen and tender to palpation. The patient was admitted to the hospital, and empirical treatment with intravenous ceftriaxone was initiated.

The cultures of a blood sample obtained at presentation were positive within 24 hours for Streptobacillus moniliformis, a gram-negative bacillus commonly found in the oropharyngeal flora of rats. A diagnosis of rat-bite fever was made. With ongoing treatment, the fever and arthralgias resolved within 3 days and 6 days, respectively. The patient was discharged on hospital day 7 and completed a course of treatment with oral amoxicillin. She remained well at follow-up 3 months later.