Rat-bite fever

Causes and Risks:
Rat-bite fever is caused by two separate organisms, Streptobacillus moniliformis and spirillum minus, which is introduced into the body by the bite of a rat (may occur in other wild animals as well). The disease spectrum varies depending on what organism predominates. The incubation period is one week or less and begins with fever and chills, headache, muscle aches, weakness and sore throat. A rash appears on the 2nd or 3rd day, often on the hands or feet. An arthritis develops in approximately 50% of infected people.

Symptoms subside within 1 week but irregular recurrences of the same symptoms will occur over the next several months. The illness ultimately is self-limiting and symptoms disappear. An occasional untreated case can be fatal.

A slightly different presentation of this illness is cause by Spirillum minor, which is also carried by rats and other rodents. It has a longer incubation period and the site of the bite develops into an open crusted sore. (This is sodoku).

Prevention:
Avoiding wild rats, other rodents, and rodent-contaminated products prevents rat-bite fever.

Symptoms:



Signs and Tests:
No testing is usually necessary. Occasionally, tests may be recommended to determine the specific cause of the symptoms.

Treatment:
The goal of treatment is to eliminate the infection with appropriate antibiotics:

  • penicillin (drug of choice)
  • streptomycin
  • tetracycline
  • erythromycin
  • cephalosporins

Note: Oral tetracycline is usually not prescribed for children until after all the permanent teeth have erupted; it can permanently discolor teeth that are still forming.

Prognosis:
Full recovery is expected with treatment.

Complications:



Call Your Healthcare Provider:
Call your health care provider if your child has had a recent injury or exposure to a rat or other rodent and has symptoms similar to those listed here.


Rodents (mice and rats) can be infested with fleas, lice, and mites. They are also capable of carrying a variety of infectious diseases. Courtesy of the Centers for Disease Control.)



Insects such as lice, mites, and fleas infest rats and carry a number of infectious diseases. (Courtesy of the Centers for Disease Control.)



The roof rat is one of the many rodents that can carry disease. (Courtesy of the Centers for Disease Control.)