Murine typhus, also known as "endemic typhus," "Mexican typhus," and "flea-borne typhus," is a flea-borne infection of humans worldwide. Symptoms are similar to those of epidemic typhus fever (transmitted by the human body louse), but typically much less severe. If untreated, patients with murine typhus can require hospitalization, but the case fatality rate is only about 2% in the U.S. However, travelers to Asia and African should note that the case fatality rate is thought to approach 70% in certain areas in which murine typhus occurs.
In the U.S., 20-80 cases of murine typhus are reported each year, but many more cases go undiagnosed. The vast majority of cases occur in Texas, but several are reported each year in California and Hawaii. The causative agent is a bacterium that exists primarily in rodents in urban areas. However, murine typhus also exists in rural areas in a transmission cycle that involves opossums, feral cats, feral dogs, and the cat flea Ctenocephalides felis.
A disease very similar to murine typhus appears to be caused by a closely related species of bacterium with the scientific name Rickettsia felis. The cat flea, Ctenocephalides felis, is thought to be the vector to humans, and the mode of transmission may be via flea bite instead of by contact with infected flea feces.
- A bacterium with the scientific name Rickettsia typhi (R. mooseri in older literature).
- It is an intracellular parasite that infects cells lining the walls of small blood vessels.
- In the U.S.: nearly all cases reported from southern Texas, southern California, and Hawaii.
- Headache, backache, joint pains, and nausea.
- Spotted rash appearing initially on the body, which subsequently may develop on arms and legs.
- In urban areas: several species of rodents including mice and rats (especially the Norway rat).
- In rural areas: opossums and feral cats.
- NOTE: Reservoir hosts of Rickettsia typhi typically show no signs of the infection.
- In urban areas: the Oriental rat flea, Xenopsylla cheopis.
- In rural areas: the cat flea, Ctenocephalides felis.
- Primarily via infected flea feces scratched into skin or rubbed into an eye.
- NOTE: Transovariole transmission has been documented in female Oriental rat fleas.
- NOTE: Laboratory research suggests that transmission is possible via bites of the cat flea.
- Difficult because initial symptoms are similar to several other diseases, including epidemic typhus fever.
- Serological tests are needed to confirm a diagnosis.
- A physician prescribed antibiotic.
- There is no vaccine available in the U.S.
- Do not provide foods that attract reservoir animals such as rodents, opossums, and feral cats.
- Do not provide places for reservoir animals to hide or live.
- Consult with a veterinarian regarding flea control on pets.