Rat-bite fever is an acute, rare disease caused primarily by Streptobacillus moniliformis. In some parts of the world, particularly Asia, another bacterium Spirillum minus causes spirillary rat bite fever. Rats can carry these bacteria but generally do not show any signs of illness. It can be transmitted throughout food or water that is contaminated with rat feces or urine. Symptoms depend on the bacteria that caused the infection. Symptoms include recurrent fever, rash, and arthralgias. This condition is diagnosed by detecting the bacteria in skin, blood, synovial fluid, or lymph nodes.
The exact incidence of Rat-bite fever is not known and many cases go undiagnosed since this bacteria is likely to respond to empiric antibiotic therapy. In Australia, it is considered one of the top five rodent-borne infections. Rat-bite fever may cause complications like infection of the brain or soft tissue, infection of the heart valves, inflammation of the parotid glands, the tendons and the heart lining. It is easily treated with treated with antibiotics (penicillin or tetracyclines for 7-14 days). Patients who have rats as pets should be advised to take proper protective measures against infection.