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Rat Bite Fever, a Fatal Case of Streptobacillus moniliformis Infection in a 14-Month-Old Boy


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Priya Banerjee, M.D.
Forensic Pathology Fellow
Office of the Chief Medical Examiner
State of Maryland
111 Penn St.
Baltimore, MD 21201


Abstract:  Streptobacillus moniliformis is the primary cause of rat bite fever in North America. Children under 12 years of age are primarily infected, presenting with an acute syndrome of fever, rash, and polyarthritis. Common vectors include rats and mice. Transmission is predominantly from a bite or scratch, but contact with or ingestion of food contaminated with feces or saliva has also been reported. We report a fatal case of S. moniliformis infection in a 14-month-old-boy. At home, the child was exposed to filthy living conditions and the family had pet ferrets. Autopsy revealed a red-pink, mostly confluent rash and a circumscribed area suspicious for a possible bite mark. Cerebrospinal fluid cultures were positive for S. moniliformis. This case highlighted key features, such as the morbiliform rash, but lacked lymphadenopathy or joint manifestations. It is important to consider rat or rodent exposure as a source of infection.