Rat bite fever is an acute, rare disease caused primarily by the bacterium Streptobacillus moniliformis. Spirillary RBF or sodoku is caused by Spirillum minus and occurs mostly in Asia. Rats are carriers (the reservoir) of both bacteria but rarely show signs of illness. 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 excreta. Actual incidence of Rat bite fever is unknown because it is not a notifiable disease, and many cases go undiagnosed since the bacteria responds to empiric antibiotic therapy.
Symptoms of the streptobacillary form include recurrent fever, rash, polyarthritis and spirillary form causes relapsing fever, rash, and regional lymphadenitis. The disease is diagnosed by detecting the bacteria in skin, blood, synovial fluid, or lymph nodes. Rat-bite fever is treated with antibiotics (penicillin or tetracyclines for 7-14 days). Alternative drugs include ampicillin, cefuroxime, and cefotaxime for the patients who are allergic to penicillin.