Informational Item

Murine Typhus

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What is murine typhus?

Typhus is caused by a small bacteria call Rickettsia. The term “murine” indicates that the disease is related to rats. In the United States typhus occurs mostly in the Southeastern and Gulf States and in Southern California. Typhus is also found in remote areas of North, Central, and Southern Africa, middle and western areas of Asia, and Mexico.

Today, fewer than 80 cases are reported annually in the U.S. Most of these cases occur in Texas and California. California cases tend to occur in suburban foothill settings in Southern California due to exposure to certain animals and their fleas.

How is murine typhus transmitted?

Fleas carry the bacteria and shed it in their feces. When a flea bites a person and begins to suck blood, it will often also defecate near the bite site. A person who scratches the flea bite can scratch some of the infectious feces into the bite wound. The bacteria can also enter through contamination of the eye, nose, or mouth. Rarely, the disease may also be acquired by inhalation of dried infective flea feces. During development, however, flea larvae fail to mature at temperatures below 55˚F (13˚C) and above 95˚F (35˚C). They die at relative humidity below 45% and above 95%, and hence, are rarely found outdoors in arid climates such as ours in the Coachella Valley. So, although rats are commonly found locally, the deficiency of fleas greatly reduces the risk of disease transmission.

How does the disease maintain itself?

Most commonly, the bacteria lives in rats, mice, and other small mammals and their associated fleas. In southern California and Texas, fleas from cats and opossums have been carriers of the disease. The highest incidences of cases occur during the summer months when rats and their fleas are most active and abundant.

What are the symptoms of this disease and how is it treated?

Most infected persons experience fever, headache, and joint pain six to fourteen days after contact with an infected flea. A common sign is a rash that begins on the chest and spreads to the sides and back. The rash may last only a few hours. Extremely high fever (106˚ F) may last up to two weeks. Very few people who get typhus die, but people over fifty years of age can get severely ill. Fortunately, antibiotics can effectively treat typhus.

Information courtesy of the State of California Health and Human Services Agency, Division of Communicable Disease Control, Infectious Disease and Arthropods (Jerome Goddard), and Julian R. Yates III Extension Urban Entomologist, College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa