Rickettsiae are a type of bacteria that can live only inside the cells of other organisms. Murine means related to rats and mice. Thus, the rickettsiae that cause murine typhus live mainly in rats and mice (the hosts).
Murine typhus occurs throughout the world, although not many people are infected. The infection is transmitted to people by rat, mouse, and cat fleas.
In the United States, most cases of murine typhus occur in suburban areas of Hawaii, Texas, and California. In these states, the rickettsiae often live in opossums and cats.
Symptoms of murine typhus begin about 6 to 18 days after bacteria enter the body. People have shaking chills, fever, and a headache. The fever lasts about 12 days. A rash may appear a few days after other the other symptoms. At first, it occurs only in a few places on the torso, then spreads to the limbs.
Murine typhus rarely causes death, but death is more likely in older people.
The diagnosis of murine typhus is suggested by symptoms.
To confirm the diagnosis, doctors may do an immunofluorescence assay, which uses a sample taken from the rash (biopsy). Or they may use the polymerase chain reaction (PCR) technique to enable them to detect the bacteria more rapidly.
Doctors may do blood tests that detect antibodies to the bacteria. However, doing the test only once is not enough. The test must be repeated 1 to 3 weeks later to check for an increase in the antibody level. Thus, antibody tests do not help doctors diagnose the infection immediately after someone becomes ill but can help confirm the diagnosis later.
There is no vaccine to prevent murine typhus.
Prevention of murine typhus involves measures to reduce contact with infected fleas.
Treatment of murine typhus usually consists of the antibiotic doxycycline, given by mouth. People take the antibiotic until they improve and have had no fever for 48 hours, but they must take it for at least 7 days.
Chloramphenicol is also effective but can have serious side effects and is not available in the United States.