Rat-bite fever is a rare disease spread by infected rodents.

Rat-bite fever can be caused by the bacteria, Actinobacillus muris (formerly called Streptobacillus moniliformis) and Spirillum minus. Most cases of rat-bite fever occur in Japan, where it is called sodoku.

The disease has also been seen in:

• Africa
• Australia
• Europe
• North and South America

Most people get rat-bite fever through contact with urine or secretions from the mouth, eye, or nose of an infected animal. This most commonly occurs though a bite, yet some cases may occur simply through contact with these secretions.

The source of the infection is usually a rat. Other animals that may cause infection include squirrels, weasels, and gerbils.

• Chills
• Fever
• Headache
• Muscle aches
• Open sore at the site of the bite in sodoku
• Rash -- may be red/purple plaques in sodoku
• Swollen, red, and painful joints (not usually seen in sodoku)

This condition is diagnosed by detecting the bacteria in skin, blood, joint fluid, or lymph nodes. Blood antibody tests may also be used.

Rat-bite fever is usually treated with antibiotic therapy. Your health care provider may prescribe penicillin or tetracyclines for 7-14 days.

The outlook is excellent with early treatment.

• Abscesses of the brain or soft tissue
• Endocarditis
• Infection of the heart valves
• Inflammation of the parotid glands (parotitis)
• Inflammation of the tendons (tenosynovitis)
• Pericarditis

Call your health care provider if:

• You or your child has had recent contact with a rat or other rodent
• The person who was bitten has symptoms of rat-bite fever

Avoiding contact with rats or rat-contaminated dwellings may help prevent rat-bite fever. Taking antibiotics by mouth after a rat bite may also help prevent this illness.

Washburn RG. Streptobacillus moniliformis (rat-bite fever). In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 6th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2005: chap 228.