Rat-bite Fever (RBF)

What is Rat-bite fever (RBF)?

Rat-bite fever (RBF) is an infectious disease that is caused by a bacteria. People can get infected with this bacteria from contact with infected rodents or consumption of contaminated food or water. If not treated, RBF can be a serious or even fatal disease.

Who gets RBF?

While anyone can become ill with RBF, those who live in buildings with rat infestations, those who handle rats as part of their job (such as those who work in laboratories or pet stores), or those who have rats as pets, may be at increased risk.

How is RBF spread?

RBF is not spread from one person to another. The most common ways the RBF bacteria is spread are:

  • Bites or scratches from infected rodents (such as rats, mice, and gerbils).
  • Handling rodents with the disease (even without a bite or scratch). Rodents that are carrying the bacteria that cause RBF do not show signs of illness, so it's not possible to tell if a rodent carries the bacteria just by looking at it.
  • Consuming food or drink contaminated with the bacteria from rodent droppings or urine.

What are the symptoms of RBF?

People with RBF will often develop a fever and a rash as well as vomiting, joint pain, muscle aches and a headache.

How soon after exposure do symptoms appear?

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

How is RBF diagnosed?

RBF should be suspected in people with rash, fever, and arthritis and a known or suspected history of rodent exposure. The bacteria that causes RBF can be hard to grow in culture but can sometimes be identified in blood or other body fluids.

What is the treatment for RBF?

If you have symptoms of RBF after exposure to rats or other rodents, 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.

Do people who have been in contact with someone with RBF infection need to be tested and treated?

RBF cannot spread between people.

How can RBF be prevented?

You can protect yourself from RBF by:

  • Avoiding contact with rodents or places where rodents may be present.
  • Avoiding consumption of food, milk or water that may have come in contact with rodents.

If you handle rats or clean their cages:

  • Wear protective gloves.
  • Avoid touching your mouth and face after handling rodents.
  • Practice regular hand washing.

How can I learn more about Rat-bite fever?

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Last Updated: May 13, 2025