What Is Murine Typhus (Flea-Borne Typhus)?

Reviewed on 12/15/2022
Murine Typhus (Flea-Borne Typhus)
Severe cases of flea-borne murine typhus are uncommon, and most people recover completely even without active treatment.

Murine typhus is a rare flea-borne infectious disease caused by the bacterium Rickettsia typhi, which is present in fleas and their feces. Because of advances in cleanliness and rat control measures, the incidence of this disease is rarer in the United States than in underdeveloped countries.

Fleas defecate while feeding, and infection occurs when their feces containing bacteria come into contact with the bite site or other wounds, and are inhaled, swallowed, or transmitted to the eye. Cats, wild opossums, rats, mice, and other rodents are some animal reservoirs of fleas that can transmit murine typhus.

Pathogens can be transmitted to people through bites. Fleas are natural carriers of R. typhi and infected female fleas can pass organisms to their offspring. The distribution is irregular but seen globally.

Although the prevalence of murine typhus is low, the rate of infection is high in rat-infested places.

What Are the Symptoms of Murine Typhus?

Flea-borne typhus symptoms appear within two weeks of contact with infected fleas or flea soil. People may not realize they have been bitten by a flea or exposed to flea soil, so inform your healthcare professional about any time spent outside or interaction with animals. 

The most common signs and symptoms of murine typhus include:

Severe cases of murine typhus are uncommon, and most people recover completely even without active treatment. However, if left untreated, murine typhus can result in serious sickness and organ damage (including the liver, kidneys, heart, lungs, and brain).

The mortality rate for murine typhus is one percent when adequate antibiotics are used and four percent when antibiotics are not used.

How Does a Medical Practitioner Diagnose Murine Typhus?

A physical examination and thorough information about the symptoms are mostly used to make a diagnosis. You may be questioned if you have ever been bitten by fleas. If your doctor detects typhus, you will be given medications immediately soon.

To confirm the diagnosis, blood tests will be done.

Indirect immunofluorescence antibody assay

Serologic testing for R. typhi IgG and IgM antibodies can be used to make a laboratory diagnosis. Serology conducted within the first week of symptom onset can often be false-negative. 

A matched serology of acute and convalescent samples (taken two weeks later) exhibiting a fourfold increase in IgG titers is required for an R. typhi diagnosis. However, because not all people with murine typhus return for further testing, a possible diagnosis can be made only on a single positive sample with supporting clinical and laboratory evidence.

It is common to find abnormal levels of various serologies in the laboratory findings, such as:

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What Are the Treatment Options for Murine Typhus?

Treatment should last at least five days or until the person becomes afebrile after 48 hours. People suspected to have murine typhus should be treated as soon as possible, rather than waiting for test confirmation.

  • Antibiotics are effective in treating flea-borne typhus.
  • Doxycycline is the preferred therapy for adults.

What Measures Should Be Taken to Prevent Murine Typhus?

There is no vaccination available to protect against flea-borne typhus. The key to avoiding this disease is to avoid contact with fleas. Fleas identified on pets can carry flea-borne typhus. Therefore, pets must be treated with flea control treatments at regular intervals. 

  • Fleas that spread flea-borne typhus can infect both cats and dogs.
  • Fleas are usually active throughout the year.
  • Flea management is the most effective strategy to avoid exposure to flea-borne typhus.

Even indoor animals can get flea-infested. Inspect pets and pet bedding for fleas regularly. The sight of flea excrement in your pet’s fur, known as flea dirt, may be the first indication of a flea infestation. Pet owners should maintain their pets on a flea and heartworm prevention regimen.

  • Fleas can infest pets and backyard animals, causing flea-borne typhus to spread to people.
  • Fleas cannot live in the absence of a host animal.
  • Flea treatment should be administered to pets throughout the year.

Yards and residences should be maintained clean and in good shape to discourage animals from entering and dwelling. Check for any cracks or nesting spots where animals can enter and dwell. Lawns should be trimmed, and garbage or other objects must be removed. 

Feral cats, opossums, and other animals may be drawn to trash cans and other food sources. Therefore, never leave pet food out overnight. Regular use of flea control solutions on animals, including stray or neighborhood cats, can help avoid flea infestations.

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Fever is a common symptom of murine typhus.

Flea-Borne Typhus Symptom

Fever

Body temperature measurements are usually measured by temperature devices inserted on or into the rectum, mouth, axilla (under the armpit), skin, or ear (ear thermometers). Some devices (laryngoscopes, bronchoscopes, rectal probes) may have temperature-sensing probes that can record temperature continually. The most common way to measure body temperature was (and still is in many countries) with a mercury thermometer; because of glass breakage and the possibility of subsequent mercury contamination, many developed countries use digital thermometers with disposable probe covers to measure temperature from all of the body sites listed above. Disposable temperature-sensitive strips that measure skin temperature are also used. Oral temperatures are most commonly measured in adults, but rectal temperatures are the most accurate because environmental factors that increase or decrease temperature measurements have the least effect on the rectal area. Rectal temperatures, when compared to oral temperatures taken at the same time, are about 1.8 F (0.6 C) higher. Consequently, an accurate measurement of body temperature (best is rectal core temperature) of 100.4 F (38 C) or above is considered to be a "fever" and the person has a febrile illness.

Reviewed on 12/15/2022
References
Image Source: iStock image

Flea-borne (murine) typhus: https://www.cdc.gov/typhus/murine/index.html#:~:text=Flea%2Dborne%20(murine)%20typhus%2C%20is%20a%20disease%20caused,rats%2C%20cats%2C%20or%20opossums.

Manifestations and Management of Flea-Borne Rickettsioses: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7873028/

Flea-Borne (Endemic) Typhus: http://www.publichealth.lacounty.gov/acd/VectorTyphus.htm