Around a pet rat, be sure the animal is secured and not roaming free. Rats will bite or scratch if frightened or handled, so leave them alone.
If you’re accidentally bitten by a rat, you should take it seriously and seek treatment.
This article explains the possible infections that can occur from a rat bite and how to treat the wound or complications that might occur.
First Aid for Rat Bite or Scratch
There are several steps that you can and should take after a rat bite:
If you’re not the victim, practice universal precautions and wear personal protective equipment, if available, when assisting the person who has been bitten. Control the bleeding and clean the wound with soap and warm water. Clean inside the wound. Then be sure to rinse away all the soap, or it will cause irritation later. Cover the wound with a clean, dry dressing. You can put antibiotic ointment on the wound before covering it. If the injury is on a finger, remove all rings from the injured finger in case it swells. Try to trap the rodent after the bite. This way, doctors can examine it later to determine if the animal has an infection.
Signs of Infection
Rat bites often lead to infection. If the wound shows any of these signs in the hours and days after a bite, it may be infected:
RednessSwellingHeatPus drainage
Types of Infections
The main concern with rat bites is that you will develop a specific type of bacterial infection known as rat-bite fever (RBF). Humans can contract this illness if an infected rat bites or scratches them.
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 by a doctor.
Petting or handling an infected animal can transmit the bacteria, as well. People can also get RBF by eating food or drinking water contaminated by rat feces.
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 bacteria are slightly different. The good news is that rat-bite fever can be effectively treated with an antibiotic. If left untreated, though, rat-bite fever can be potentially fatal.
Streptobacillus Rat Bite Fever
Watch for the following symptoms and seek medical attention right away if you experience any of them:
FeverHeadachesVomitingPain in the back and jointsRash 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 backIrritation and a possible ulcer at the bite woundSwollen lymph nodesSwelling around the wound siteA 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.
Haverhill Fever
Another form of rat-bite fever is Haverhill fever. You can contract this type of infection if you consume contaminated food or fluids. Symptoms may include severe vomiting and a sore throat.
Treatment
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 PenicillinErythromycinDoxycycline
Patients with severe forms of rat-bite fever that affect the heart could get high-dose penicillin and may receive the antibiotics streptomycin or gentamicin.
Summary
Rat-bite fever is a serious infection. 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, you should talk to your doctor about the possibility of an infection.
A Word From Verywell
As the old saying goes, prevention is worth a pound of cure. This is especially true when it comes to rat bites.
Even domesticated rodents have an unpredictable nature and may bite you or may carry bacteria that could cause rat-bite fever. Take any wound you receive from a rat seriously and be sure to wash your hands carefully if you touch one.
