Causes

Rat-bite fever can be caused by the two different bacteria, Streptobacillus moniliformis or Spirillum minus, both of which are found in the mouths of rodents.

The disease has been seen in:

• Africa
• Australia
• Europe
• Japan
• 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.

Symptoms

Symptoms depend on the bacteria that caused the infection.

Symptoms due to Streptobacillus moniliformis may include:

• Chills
• Fever
• Joint pain, redness, or swelling
• Rash

Symptoms due to Spirillum minus may include:

• Chills
• Open sore at the site of the bite
• Rash -- may be red/purple plaques

Exams and Tests

This condition is diagnosed by detecting the bacteria in skin, blood, joint fluid, or lymph nodes. Blood antibody tests and polymerase chain reaction (PCR) techniques may also be used.

Treatment

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

Outlook (Prognosis)

The outlook is excellent with early treatment. Untreated, the death rate can be as high as 25%.

Possible Complications

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

When to Contact a Medical Professional

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

Prevention

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.

Alternative Names

Streptobacillary fever; Streptobacillosis; Haverhill fever; Epidemic arthritic erythema; Spirillary fever; Sodoku

References

Washburn RG. Rat-bite fever: Streptobacillus moniliformis and Spirillum minus. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 231.

Updated: 4/15/2012

Reviewed by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.