Rat Bite Fever

Rat bite fever is an infection characterized by sudden onset of fever, chills and headache caused by two different bacteria, actinobacillus muris and spirillum minus. Actinobacillus muris is responsible for the illness in North America, South America and Europe while spirillum minus causes illness in Asia. As the name implies the illness is spread through the bite of rats.

Where does it occur?

Actinobacillus muris is found in North America, South America and Europe infecting rats, mice, squirrels and possibly animals that feed on them like cats, dogs and weasels.

Spirillum minus is found primarily in Asia, but use of rats & mice in laboratory research means it can be seen worldwide in this setting.

How is it transmitted?

The bacteria is transmitted primarily through the bite of rats, however it can also be contracted (actinobacillus muris) by ingesting food contaminated by rat feces or saliva.

What is the risk for travelers?

The risk should be low if staying in hygienic accommodations.

How soon after exposure will one develop symptoms?

Infection caused by actinobacillus muris is typically seen a week after exposure, however it may be seen up to 3 weeks after.

Infection due to spirillum minus can be seen anywhere from 1 to 4 weeks after exposure.

What are the signs and symptoms?

The sign and symptoms vary depending on which bacteria are causing the infection.

Actinobacillus muris: (North America, South America and Europe).

There is a sudden onset of fever, chills, body aches, muscle and joint pains. Few days later a generalized whole body rash that is red in color and varies from blotchy to sandpaper or prickly type or bruise like appears. Nearly half the affected people develop swollen and painful joints, primarily the large joints like knees, ankles, elbows, wrists, shoulders and hips. Symptoms can wax and wane for weeks. If untreated it can spread to involve the heart, central nervous system, liver, spleen etc and result in death.

Spirillum minus: (Asia).

The initial bite is not noticeable in most cases, but a few days to weeks later there is painful, swollen lymph glands in the region of the rat bite. Shortly thereafter there is onset of fever, chills and sweats, however unlike above there is not much joint pains or swelling. Subsequently the person develops a rash that is varied from small red flat patches to violaceous and blotchy. The original area of rat bite that was not noticeable now becomes a small ulcer with redness and pus. The symptoms can come and go for weeks. Again if left untreated the infection can spread to multiple organ systems and lead to death.

Are there any lab tests to diagnose the illness?

The bacteria can be cultured from skin lesions, blood and body fluids

Is there any treatment?

Antibiotics like penicillin and doxycycline are effective

Is the infected person contagious?

There is no person to person transmission of the illness.

What preventive measures can be taken?

Avoid rat bites by staying in well screened and hygienic accommodations.

advice for your illness and travel
learn about an exotic disease