Murine typhus is a bacterial illness that can affect humans, often presenting with symptoms that are easily mistaken for other common infections. This article provides essential information about murine typhus, covering its origins, how it spreads, the signs to look for, and effective strategies for prevention.
Understanding Murine Typhus
Murine typhus, also known as endemic typhus or flea-borne typhus, is an infectious disease caused by the bacterium Rickettsia typhi. This bacterium primarily resides within rodents, such as rats, and spreads to humans through their fleas. The disease is found globally, particularly in tropical and subtropical regions, often in coastal areas with high rat populations.
In the United States, most cases are reported in southern California, Hawaii, and southern Texas. Cases have increased in some U.S. regions since 2008, suggesting re-emergence. Rickettsia felis can also cause a similar disease, sometimes considered a form of murine typhus due to shared symptoms.
How Murine Typhus Spreads
Murine typhus primarily spreads to humans through infected fleas, especially the Oriental rat flea (Xenopsylla cheopis) and the cat flea (Ctenocephalides felis). Fleas become infected when they feed on animals carrying Rickettsia typhi, such as rats, opossums, and sometimes cats. Once infected, a flea can carry the bacteria for the remainder of its life.
When an infected flea bites a human, it often defecates at the same time, releasing bacteria-laden feces. The bacteria can then enter the body when these flea feces are rubbed into the bite wound or other skin abrasions. Infection can also occur if the bacteria in dried flea feces are inhaled or come into contact with mucous membranes. Murine typhus does not spread directly from person to person.
Recognizing and Addressing Symptoms
Symptoms of murine typhus typically appear within 3 to 14 days after exposure to infected fleas or their feces. Common signs include fever, chills, headache, and body aches, often accompanied by a general feeling of weakness. A rash may develop in about half of patients, usually starting on the trunk around day five of the illness and then spreading to the arms and legs. Other symptoms can include nausea, vomiting, stomach pain, loss of appetite, and a cough.
Diagnosing murine typhus can be challenging because its symptoms are not specific and can resemble other viral illnesses. A detailed patient history, including any potential exposure to fleas or rodents, is important for diagnosis. Laboratory tests, such as serological assays that detect antibodies to the bacteria, are used to confirm the diagnosis. Polymerase chain reaction (PCR) assays on blood or tissue specimens can also help detect the bacteria more rapidly.
Prompt medical attention and antibiotic treatment are important for managing murine typhus. Doxycycline is the preferred antibiotic for treating this infection and is effective for patients of all ages. Early treatment significantly shortens the duration of illness and reduces severe complications. While usually a self-limited disease, untreated cases can lead to prolonged fever, lasting 2 to 3 weeks, and may result in severe illness or, rarely, be fatal.
Preventing Murine Typhus Infection
Preventing murine typhus involves reducing contact with fleas and the animals that carry them. One strategy is to control rodent populations around homes and workplaces. This includes removing potential rodent habitats like brush, rock piles, and junk, and sealing any holes in buildings where rodents could enter. Storing food, including pet food, in tightly sealed containers and keeping lids closed on trash cans can also deter rodents.
Controlling flea populations on pets and in the environment is another important preventive measure. Consult with a veterinarian about appropriate flea control products for pets, such as collars, oral medications, or topical treatments. Before initiating rodent control, treating for fleas in and around your home is advisable; otherwise, fleas may seek new hosts if their primary animal hosts are eliminated.
Personal protection measures can also reduce the risk of infection. Avoiding direct contact with wild animals, especially rodents and opossums, is recommended. When in areas where fleas or rodents might be present, wearing long-sleeved shirts and pants can reduce the risk of flea bites. Using insect repellents containing active ingredients like DEET or picaridin, applied according to product instructions, can further deter fleas.