Rat-bite fever is a rare bacterial disease spread by infected rodents.
Rat-bite fever can be caused by 2 different bacteria, Streptobacillus moniliformis or Spirillum minus. Both of these are found in the mouths of rodents.
The disease is most often seen in:
- North America
Most people get rat-bite fever through contact with urine or fluids from the mouth, eye, or nose of an infected animal. This most commonly occurs through a bite, yet some cases may occur simply through contact with these fluids.
A rat is usually the source of the infection. Other animals that may cause this infection include:
Symptoms depend on the bacteria that caused the infection.
Symptoms due to Streptobacillus moniliformis may include:
- Joint pain, redness, or swelling
Symptoms due to Spirillum minus may include:
- Open sore at the site of the bite
- Rash with red or purple patches and bumps
- Swollen lymph nodes near the bite
Exams and Tests
This condition is diagnosed by detecting the bacteria in:
- Joint fluid
- Lymph nodes
Blood antibody tests and other techniques may also be used.
Rat-bite fever is treated with antibiotics for 7 to 14 days.
The outlook is excellent with early treatment. If it is not treated, the death rate can be as high as 25%.
Rat-bite fever may cause these complications:
- Abscesses of the brain or soft tissue
- Infection of the heart valves
- Inflammation of the parotid (salivary) glands
- Inflammation of the tendons
- Inflammation of the heart lining
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
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.
Streptobacillary fever; Streptobacillosis; Haverhill fever; Epidemic arthritic erythema; Spirillary fever; Sodoku
Washburn RG. Rat-bite fever: Streptobacillus moniliformis and Spirillum minus. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 8th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2014:chap 233.
Update Date 12/7/2014
Updated by: Jatin M. Vyas, MD, PhD, Associate Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.