Rise in Murine Typhus Cases May Increase Risk of Misdiagnosis: CDC

Government warning follows at least one reported death involving a patient who developed murine typhus, which was thought to be virtually eradicated in the U.S.

Federal health officials are warning about the emergence of new cases of murine typhus, a disease once considered eradicated in the U.S., but which has now been detected in a number of cases across multiple states.

The U.S. Centers for Disease Control and Prevention (CDC) issued a murine typhus warning last month, indicating that cases of the disease, which is also known as flea-borne typhus or endemic typhus, have steadily increased since 2008 and may be much more common than in prior decades.

The agency also cautioned that the disease is often underdiagnosed, as some healthcare providers may not recognize the symptoms or consider it in their initial evaluations.

Murine typhus is a bacterial infection caused by Rickettsia typhi. Fleas become carriers after feeding on infected animals such as rats, opossums and cats, and can then transmit the bacteria to humans through their bites or feces. The disease is typically found in tropical and temperate regions, including parts of Southeast Asia, Africa, Central and South America, southern Europe, the Middle East and areas of the southern United States.

Symptoms of murine typhus typically appear 3 to 14 days after contact with infected fleas, though many people are unaware they’ve been bitten. Common symptoms include fever, chills, headache, body aches, muscle pain, rash, loss of appetite, nausea, vomiting, abdominal pain and cough. In severe cases, the infection can lead to organ damage and, although rare, may be fatal.

The CDC warning indicates an organ transplant recipient in Texas died in October 2024 from murine typhus. However, usually death occurs in less than 1% of all cases. Most cases resolve completely with proper treatment with antibiotics.

Once Believed To Be Virtually Wiped Out

The U.S. saw more than 2,000 cases of murine typhus every year with 42,000 cases reported from 1931 to 1946. But by the 1950s the disease had largely disappeared with fewer than 50 cases reported each year up until the early 2000s.

However, according to CDC data, southern states began to see an increase in cases around the mid-2000s. Texas reported nearly 700 cases per year since 2018. California also saw an increase in cases with roughly 200 reported each year during the same time period.

Case counts are still well below the 1940’s average of 5,400, but CDC officials warn the disease is making a serious comeback.

Murine Typhus Misdiagnosis Risks

CDC officials warn that it is important for patients to see a doctor and receive testing to confirm murine typhus if symptoms arise. Patients can have a fever for up to three weeks, which if left untreated, can lead to organ failure and other side effects.

Murine typhus is often misdiagnosed because symptoms are similar to other illnesses, like COVID-19, west Nile virus and Rocky Mountain spotted fever.

The CDC says it’s unclear what is causing the rise in cases, but once a flea is infected with the disease, it remains infected for the rest of its life. 

When an infected flea bites a person or animal, the bite breaks the skin causing a wound. Fleas also defecate when they feed on animals and the feces, also known as flea dirt, can enter the bite or other wounds. The flea dirt contains bacteria that causes the infection. People can also breathe in infected flea dirt and rub it into their eyes.

Researchers said less than 5% of patients will remember a fleabite or flea exposure in the one or two weeks before becoming sick.

Risk factors of murine typhus include spending time outdoors, contact with free-roaming cats, rats and opossums. To lower the risks, the CDC recommends that people should properly store food to avoid rodents and scavenging animals, remove brush and clutter outside of the home, and keep trash and compost lids closed.

In addition, the CDC warned against feeding or petting wild or stray animals. The agency also recommends people avoid flea contact by using repellents to prevent bites and keeping pets flea-free with flea collars and medication.