Rat bite fever rash: what to know

Rat bite fever is a bacterial infection associated with rats and other rodents. The rash may consist of small red or purple spots, raised areas, or patches on the hands and feet, and it can spread to other parts of the body. It may appear alongside fever, chills, headache, muscle aches, vomiting, or painful joints. A rash after a bite can also have other causes, including a local wound infection or a separate viral illness, so its appearance alone cannot identify the cause.

Wash the bite or scratch with running water and soap, cover it with a clean dressing, and avoid scratching the rash. Note when the exposure happened, where it occurred, whether the skin broke, and whether the animal can be identified safely. Arrange prompt medical assessment and mention any fever, joint symptoms, or worsening redness. A clinician may examine the skin and wound and decide whether testing or prescription antibiotics are needed.

Seek urgent care for a rapidly spreading rash, severe weakness, confusion, trouble breathing, fainting, repeated vomiting, a very painful or swollen joint, or redness and swelling moving away from the wound. Same-day advice is appropriate for any fever after a rat bite or contact with rodent saliva, urine, or droppings, especially when the wound is on the hand, face, or near a joint.

Ask whether the rash pattern fits rat bite fever, whether the wound needs a culture or other test, which antibiotic plan is suitable, and how to monitor the skin and joints during recovery.