Rat Bite Fever: Symptoms, Transmission, and Treatment

Medically Reviewed By Michaela Murphy, PA-C
Was this helpful?

Rat bite fever is a bacterial infection typically caused by Streptobacillus moniliformis and Spirillum minus, commonly found in the throat of rodents. It is commonly transmitted to humans through bites or scratches from infected rodents. Treatment typically includes antibiotics. This article discusses the causes and symptoms of rat bite fever. It also goes over diagnosis and treatment options.

What is rat bite fever?

Image of a white rat cleaning its face on a wooden floor
Saptak Ganguly/Stocksy United

Rat bite fever is a bacterial infection caused by Streptobacillus moniliformis and Spirillum minus, which are carried by rats and transmitted to humans through bites. It can also less commonly be caused by Streptobacillus notomytis (S. notomytis).

Rat bite fever can be transmitted through scratches or bites from other rodents as well, such as squirrels, mice, and hamsters. This condition can also spread to humans through the bites of animals like cats and dogs that have been bitten by an infected rodent. However, this is less common.

You can also get rat bite fever by eating or drinking foods or liquids that have been contaminated with rodent urine or feces. In this case, it is known as Haverhill fever.

Read about rat bites.

How common is rat bite fever?

Rat bite fever is not common in the United States. It is more common in Japan, where it is known as sodoku. It has also been reported in Africa, Europe, and Australia.

Rat bite fever is more common in areas where rats live closer to humans or where there are large numbers of wild rats — for example, in cities and also in developing countries where living conditions may be more crowded and less rodent-proof.

What are symptoms of rat bite fever?

The symptoms of rat bite fever include:

  • fever or chills 
  • muscle aches and pains
  • headache 
  • nausea and vomiting 
  • generalized skin rash 
  • broken skin at the bite site 
  • painful swelling of the lymph nodes in your:
    • neck
    • groin
    • armpits
    • abdomen 
  • joint pain and swelling

Symptoms and incubation periods may differ depending on the bacteria that causes rat bite fever. If you experience any of these symptoms, it is important to seek medical attention immediately. 

How is rat bite fever transmitted?

Rat bite fever is transmitted through the bite or scratch of an infected rat or other rodents. However, it can also be transmitted through ingesting food or water contaminated by rat droppings, urine, or saliva.

In some other cases, it may spread through contact with surfaces containing the bacteria because the bacteria can enter the body through open skin, such as cuts.

It is important to note that rat bite fever does not spread from one person to another.

What are treatments for rat bite fever?

Treatment for rat bite fever is usually supportive and may include antibiotics if the person is at risk of developing a life threatening infection. These antibiotics can include penicillins, such as penicillin G, or tetracyclines, such as doxycycline, which can be prescribed for a period of 14 days or more, depending on the severity of the symptoms. Doxycycline is generally prescribed only if you have an allergy to penicillin.

You can also take over-the-counter pain relievers like ibuprofen (Advil), acetaminophen (Tylenol), and naproxen (Aleve) to help with pain and inflammation. It is also a good idea to drink plenty of fluids to prevent dehydration and get plenty of rest.

If you are experiencing more severe symptoms than a fever, contact your doctor as soon as possible. Severe cases of rat bite fever may require hospitalization.

How do doctors diagnose rat bite fever?

Doctors may diagnose rat bite fever by taking a thorough medical history and conducting a physical exam. Your doctor will ask questions about your symptoms, how long you’ve had them, your risk factors, and whether you’ve recently been in contact with rodents or other animals.

They’ll also want to know if any family members have been ill recently.

Your doctor will examine the area of your body where a rat or other rodent bit you. If there’s swelling or redness around the wound, it is likely a sign of rat bite fever. If you cannot pinpoint precisely where you were bitten because it happened a while ago, doctors may order blood tests to help identify the cause of your symptoms.

What are possible complications of rat bite fever?

There are multiple possible complications of rat bite fever, including:

What is the outlook for people with rat bite fever?

The outlook for people with rat bite fever depends on the severity of their symptoms and how quickly they seek treatment.

In most cases, people who are treated early and receive proper care have a positive outlook and will recover within 1 or 2 weeks. However, If the condition is left untreated, it can have a mortality rate of up to 10%.

Other frequently asked questions 

Michaela Murphy, PA-C, has reviewed the questions people frequently ask about rat bite fever.

Can rat bite fever be cured?

Yes, rat bite fever can be cured using antibiotics such as penicillin and doxycycline. However, it’s important to seek treatment as soon as possible. 

Should I be worried about rat bite fever?

Yes, rat bite fever can lead to serious complications if left untreated. In some cases, it can even lead to death. If you develop any signs and symptoms of this condition, seek medical attention immediately. It is important to remember, however, that rat bite fever is rare in the United States.

How long does rat bite fever last?

The length of time that rat bite fever lasts can vary. In most cases, it will last between 1 and 3 weeks. However, it can sometimes be longer or shorter than that.


Rat bite fever is a bacterial infection that’s usually transmitted through the bite of a rat or other rodent. It is caused by the bacteria Streptobacillus moniliformis and Spirillum minus, commonly found in rodents. It can also less commonly be caused by the bacteria S. notomytis.

Symptoms include fever, headaches, joint pain, and a rash that can also develop on the skin at the site of the rat bite. These symptoms may appear within 2 days of being bitten.

Treating rat bite fever may include antibiotics like penicillin and doxycycline and pain relievers like ibuprofen.

To prevent it, avoid contact with rats or other rodents. If a rat or other rodent bites you, seek medical attention right away.

Was this helpful?
Medical Reviewer: Michaela Murphy, PA-C
Last Review Date: 2023 Feb 2
View All Infections and Contagious Diseases Articles
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
  1. Gupta, M., et al. (2022). Rat-bite fever. https://www.ncbi.nlm.nih.gov/books/NBK448197/
  2. Information for health professionals and laboratory personnel. (2019). https://www.cdc.gov/rat-bite-fever/health-care-workers/index.html
  3. Signs and symptoms of rat-bite fever. (2019). https://www.cdc.gov/rat-bite-fever/symptoms/index.html