Rat bite fever (Streptobacillary fever; Streptobacillosis; Haverhill fever; Epidemic arthritic erythema; Spirillary fever; Sodoku) is an acute, rare disease caused primarily by the bacterium Streptobacillus moniliformis. Another bacterium Spirillum minus causes spirillary rat bite fever in Asian countries. Rats are carriers (the reservoir) of both bacteria but rarely show signs of illness. Disease has been reported in mice, birds, guinea pigs, and nonhuman primates. The majority of cases are due to the animal's bite. It can also be transmitted throughout food or water that is contaminated with rat feces or urine.
The disease is most often seen in Asia, Europe, North America. The exact incidence is unknown. Higher risk groups include laboratory workers, the owners of pet rats, pet shop personnel and veterinarians. Since rats have become popular pets, children now account for more than 50% of cases. Symptoms of the streptobacillary form include recurrent fever, rash, and arthralgias and the spirillary form causes relapsing fever, rash, and regional lymphadenitis. Rat bite fever can be treated readily with antibiotics (penicillin and tetracyclins), but untreated S. moniliformis infections are estimated to be fatal.