Rat Bite Treatment With or Without Infection

A bite or scratch from a rat causes rat bite fever

A rat bite can be dangerous if it develops into a bacterial infection, called rat bite fever. If you are bitten by a rat, take it seriously and treat it right away.

While rats are generally more afraid of you than you are of them, you can never be sure how a wild animal will act. Even pet rats can bite if they are frightened and can harbor the same kinds of bacteria in their mouths as wild rodents.

This article explains the different types of infections that can occur from a rat bite, how to treat the bite at home, and when to call a healthcare professional.

how to treat a rat bite

Verywell / Brianna Gilmartin

Right After a Rat Bites: First Aid Steps

There are several steps should take right after you or someone else has been bitten by a rat:

  1. If you're assisting someone else who has been bitten by a rat, practice universal precautions and wear personal protective equipment if available.
  2. Control the bleeding by pressing firmly on the wound with a gauze pad or clean paper towel, Clean the wound with soap and warm water, being sure to clean inside the wound. Be sure to rinse away all the soap, or it will cause irritation later.
  3. Cover the wound with a clean, dry dressing. You can put antibiotic ointment on the wound before covering it.
  4. If the injury is on a finger, remove all rings from the injured finger in case it swells.
  5. Try to trap the rodent after the bite. This way, a health professional can examine it later, if necessary, to determine if the animal has an infection.

When to See Your Doctor

Even if you have treated the bite at home, aways consult your healthcare provider after a rat bite. You may need a tetanus immunization or stitches. Wounds on the face or hands are of special concern due to the risk of scarring or loss of function and should always be evaluated.

Infected Rat Bite: How to Tell

A rat bite looks like a small puncture wound or small cut. Rat bites often lead to infection. Symptoms of rat bite fever usually begin within three to 10 days after being bitten. If the wound shows any of these signs in the days after a bite, it may be infected:

  • Fever
  • Redness
  • Swelling
  • Heat
  • Pus drainage
  • Joint pain or swelling
  • Rash on the hands and feet (typically two to four days after the fever begins)

Types of Rat Bite Fever

Rat bite fever is not common. However, cases may not always be identified since the bacteria are difficult to diagnose, and the condition often responds well to prescribed antibiotics. There are between 20,000 and 40,000 rat bites in the United States each year; the risk of developing rat bite fever is estimated to be about 10%.

Petting or handling an infected rat can transmit the bacteria even if you aren't bitten. People can also get RBF by eating food or drinking water contaminated by rat feces. If rats are able to enter your home, it is possible for them to bite people in their sleep.

The two bacteria responsible for rat bite fever are: 

  • Streptobacillus moniliformis or S. moniliformis (most common in the United States)
  • Spirillum minus or S. minus (most common in Asia)

The signs and symptoms of infection from each bacterium are slightly different. Fortunately, rat bite fever can be effectively treated with an antibiotic. If left untreated, though, rat bite fever can potentially be fatal.

Streptobacillus Rat Bite Fever

Watch for the following symptoms and seek medical attention right away if you experience any of them:

  • Fever
  • Headaches
  • Vomiting
  • Pain in the back and joints
  • Rash on the hands and feet, usually accompanied by one or more swollen joints

Symptoms of rat bite fever usually appear three to 10 days after the exposure or bite but may occur up to three weeks later. A rash usually appears two to four days after the fever.

Just because the bite or scratch seems to be getting better, don't assume you're in the clear. The infection can still be in your body. In fact, you may not have a fever until after the wound is healed.

Complications from S. moniliformis infections include the formation of pockets of infected fluid, called abscesses, in your belly or other parts of the body. The infection can also lead to hepatitis in the liver, meningitis, pneumonia, and a kidney disorder known as nephritis.

Approximately 10% of people who develop S. moniliformis die of the infection.

Spirillum Rat Bite Fever

Symptoms of S. minus RBF usually come on one to three weeks after being exposed to an infected rodent. They are more variable than streptobacillus RBF, but may include:

  • Fever, which may go away and come back
  • Irritation and a possible ulcer at the bite wound
  • Swollen lymph nodes
  • Swelling around the wound site
  • A purple or reddish rash

Without treatment, S. minus RBF can be fatal as the infection spreads to the heart, brain, lungs, or other internal organs.

Rat Bites and Rabies Risk

Rats are not a major source of rabies infection. In fact, it's very rare for humans to contract rabies from any rodent. Bat bites are the most common source of rabies. Raccoons, skunks, and foxes can also transmit the disease.

Haverhill Fever

Another form of rat bite fever is Haverhill fever. You can contract this type of infection if you consume food or fluids that have been contaminated by bacteria from a rat. Symptoms may include severe vomiting and a sore throat.

Antibiotic Treatment for Rat Bite Fever

Rat bite fever should always be treated by a doctor. If untreated, rat bite fever can cause serious complications that could lead to death. Your doctor will prescribe antibiotics, which usually include:

  • Amoxicillin 
  • Penicillin
  • Erythromycin
  • Doxycycline 

Patients with severe forms of rat bite fever that affect the heart may receive high-dose penicillin and the antibiotics streptomycin or gentamicin.

Summary

Rat bite fever is a serious infection that is often harmful to humans. S. moniliformis bacteria found in American rats is associated with rash and flu-like symptoms. S. minus bacteria found in Asian rats may cause swollen lymph nodes and irritation around the wound. Both types of bacteria cause an infection that can be fatal if it’s not treated. 

Thankfully, the condition can be cured with antibiotics. Avoiding interaction with rats whenever possible is the best prevention, but if you do find yourself bitten, scratched, or even exposed to a rat, contact a health professional right away.

Frequently Asked Questions

  • Can you get rat bite fever from a mouse?

    Yes, it is possible to get rat bite fever from a mouse. Other rodents can carry the bacteria for rat bite fever, including mice, squirrels, gerbils, and guinea pigs. If you are bitten by a mouse or other rodent, be sure to clean the wound and contact your healthcare provider.

  • Can mice carry rabies?

    Mice can carry rabies, but it is extremely rare. There are very few documented cases of rabies-infected mice. In addition, it is unknown if they can transmit it to humans. The same is true for hamsters, guinea pigs, chipmunks, rats, rabbits, and hares. To be on the safe side, it may still be worth contacting your healthcare provider if you get bit by a rodent or wild animal.

11 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention (CDC). Signs and Symptoms of Rat-Bite Fever.

  2. Rodino KG, Miller NE, Pethan KD, DeSimone DC, Schuetz AN. The brief case: rat bite fever from a kiss. J Clin Microbiol. 2019;58(1). doi:10.1128/JCM.00677-19

  3. Centers for Disease Control and Prevention (CDC). How is Rat-Bite Fever Spread?

  4. Connecticut Department of Energy and Environmental Protection. Rodent management.

  5. Akter R, Boland P, Daley P, Rahman P, Al Ghanim N. Rat bite fever resembling rheumatoid arthritis. Can J Infect Dis Med Microbiol. 2016:7270413. doi:10.1155/2016/7270413

  6. Centers for Disease Control and Prevention (CDC). Rat-Bite Fever (RBF): Etiologic Agent.

  7. National Environmental Health Association. Rat Bite Fever.

  8. Centers for Disease Control and Prevention (CDC). Avoid Risk of Rabies from Bats.

  9. Madhubashini M, George S, Chandrasekaran S. Streptobacillus moniliformis endocarditis: case report and review of literature. Indian Heart J. 2013;65(4):442-6. doi:10.1016/j.ihj.2013.06.019

  10. Centers for Disease Control and Prevention (CDC). Rat-Bite Fever (RBF): Infection in Animals.

  11. Centers for Disease Control and Prevention (CDC). Other Wilds Animals.

Additional Reading
  • Centers for Disease Control and Prevention. Rabies.

  • Centers for Disease Control and Prevention. Rat-bite fever.

Rod Brouhard, EMT-P

By Rod Brouhard, EMT-P
Rod Brouhard is an emergency medical technician paramedic (EMT-P), journalist, educator, and advocate for emergency medical service providers and patients.