Rat-bite fever (RBF)

Rat-bite fever (RBF) is an infectious disease that can be caused by two different bacteria. Streptobacillary RBF is caused by Streptobacillus moniliformis in North America while spirillary RBF or sodoku is caused by Spirillum minus and occurs mostly in Asia. People usually get the disease from infected rodents or consumption of contaminated food or water. When the latter occurs, the disease is often known as Haverhill fever. If not treated, RBF can be a serious or even fatal disease.


Symptoms are often different for the two types of RBF:

  • Streptobacillary RBF
  • Spirillary RBF

Streptobacillary RBF Symptoms

  • Fever
  • Vomiting
  • Headache
  • Muscle pain
  • Joint pain
  • Rash

Symptoms usually occur 3-10 days after exposure to an infected rodent, but can be delayed as long as 3 weeks. By this time, any associated bite or scratch wound has usually healed.

Within 2-4 days after fever onset, a maculopapular rash may appear on the hands and feet. This rash is identified by flat, reddened areas with small bumps. One or more joints may then become swollen, red, or painful.

Spirillary RBF (also known as Sodoku) Symptoms

Symptoms can vary and often include:

  • Fever (that may occur repeatedly)
  • Development of an ulcer at the bite wound (when applicable)
  • Swelling near the wound
  • Swollen lymph nodes
  • Rash (occurs following partial healing of the wound)

These symptoms usually occur 7-21 days after exposure to an infected rodent.

The symptoms associated with Haverhill fever (RBF you can get from consuming contaminated food or water) can differ from those that occur when you get the disease through bites and/or scratches. The most notable differences may include more severe vomiting and sore throat.


There are several ways people can get RBF. The most common include:

  • Bites or scratches from infected rodents (such as rats, mice, and gerbils).
  • Handling rodents with the disease (even without a bite or scratch).
  • Consuming food or drink contaminated with the bacteria.

RBF is not spread from one person to another.

Who is at risk?

Any person who is exposed to the bacteria that cause RBF is at risk for getting the disease.

Some people who may be at increased risk include those who:

  • Live in rat-infested buildings.
  • Have pet rats at their home.
  • Work with rats in laboratories or pet stores.


If you have any symptoms of rat-bite fever after exposure to rats or other rodents, please immediately contact your health care provider. Be sure to tell your provider of your exposure to rodents.

If you have RBF, your doctor can give you antibiotics that are highly effective at curing the disease. Penicillin is the antibiotic most often used. If you are allergic to penicillin, your doctor can give you other antibiotics.

Without treatment, RBF can be serious or potentially fatal. Severe illnesses can include:

  • Infections involving the heart (endocarditis, myocarditis, or pericarditis)
  • Infections involving the brain (meningitis)
  • Infections involving the lungs (pneumonia)
  • Abscesses in internal organs

While death from RBF is rare, it can occur if it goes untreated.