Rat-bite fever

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

  • Alternative Names
    • Streptobacillary fever; Streptobacillosis; Haverhill fever; Epidemic arthritic erythema; Spirillary fever; Sodoku

  • Causes
    • 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:

      • Asia
      • Europe
      • 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:

      • Gerbils
      • Squirrels
      • Weasels
  • 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
      • Fever
      • 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:

      • Skin
      • Blood
      • Joint fluid
      • Lymph nodes

      Blood antibody tests and other techniques may also be used.

  • Treatment
    • Rat-bite fever is treated with antibiotics for 7 to 14 days.

  • Outlook (Prognosis)
    • The outlook is excellent with early treatment. If it is not treated, the death rate can be as high as 25%.

  • Possible Complications
    • 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
  • 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.

  • 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. 8th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2014:chap 233.