Rat Bites: First Aid, Transmission and Treatment

Picture of Rat Bites


Rats are equipped with large teeth and administer painful bites when threatened. Healthy rats typically avoid people and prefer to be active when buildings are quiet. However, when cornered, they will lunge and bite to defend themselves. The saliva of some species of rats carries hazardous diseases, such as leptospirosis and Hantavirus. In rare cases, rat bite victims may contract rat-bite fever. Humans bitten by rodents are also susceptible to tetanus infections.

Rat bites may be shallow or deep. Some display single puncture wounds, while others display multiple abrasions. Bleeding often occurs. Although infection is rare, all rodent bites should be promptly and thoroughly cleaned and disinfected. Tetanus immunizations may be required for those who have not received them in recent years. Despite common belief, no rodent bites in North America have ever resulted in the transmission of rabies. However, a person bitten by a rat should seek a medical professional.


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.


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:Set featured image

  • Gerbils
  • Squirrels
  • Weasels

Signs and Symptoms

Rat-bite fever symptoms can vary depending on which organism is responsible for the disease. When the disease is caused by S moniliformis, the bite, which usually heals quickly, is followed 3 to 10 days later by:

  • Fever and chills
  • Headache
  • Skin rash (mostly on the arms and leg )
  • Muscle pain
  • Arthritis (particularly in the knees)
  • Vomiting and diarrhea
  • Complications (eg, abscesses, pneumonia, meningitis, heart inflammation)

With infections caused by S minus, the site of the bite may appear to heal initially, but 7 to 21 days later, the following symptoms may surface:

  • Fever and chills
  • Headache
  • Ulceration at the site of the bite with red streaks
  • Swelling of the lymph nodes
  • A skin rash with reddish-brown or purple plaques
  • Muscle pain and arthritis (rare)
  • Vomiting and sore throat (Haverhill fever)
  • Complications (eg, infection of the heart, pneumonia, meningitis, hepatitis)

Both forms of rat-bite fever may result in recurrent fevers, sometimes for months or years.


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.


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.

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

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