What is Rat-bite fever?

Rat-bite fever (RBF) is an infectious disease caused by two different organisms, Streptobacillus moniliformis and Spirillum minus. In the United States, Rat-bite fever is primarily due to infection with S. moniliformis. Spirillum minus causes Rat-bite fever cases in countries such as Asia and Africa.

How common is Rat-bite fever in humans in the United States?

Rat-bite fever is rare in the United States. However, since RBF is not a notifiable disease, exact numbers of cases are not known.

How is infection spread to humans?

Rat-bite fever refers to an infection which usually develops after having been bitten or scratched by an infected rat. Other rodents (such as mice and gerbils) may also spread the infection to humans.

Sometimes infection can result from handling infected rats, with no reported bite or scratch.

It is also possible to become infected by ingesting food or drink (such as milk or water) contaminated with rat excrement. This form of the disease is sometimes referred to as Haverhill fever.

Who is at risk for infection?

Persons who are at risk for infection include those who work with animals in labs or pet stores and persons living in dwellings infested with wild rats. People who have pet rats may also be at risk for infection.