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Endemic rat typhus: causes, symptoms, diagnosis, treatment
Last reviewed: 05.07.2025
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Endemic typhus is a sporadic acute benign zoonotic rickettsiosis transmitted through ectoparasites of mice and rats, with a characteristic cyclical course, fever, moderate intoxication and widespread roseolous-papular rash.
Synonyms: rat-borne typhus, rat-borne rickettsiosis, flea-borne typhus, flea-borne rickettsiosis, Mediterranean rat-borne rickettsiosis, Manchurian epidemic typhus.
ICD-10 codes
- A79. Other rickettsioses.
- A79.8. Other specified rickettsioses.
Epidemiology of endemic typhus
The source and natural reservoir of infectious agents are rodents (rats and mice), their ectoparasites (fleas and gamasid mites).
Humans become infected from infected rodents in the following ways:
- contact - when rubbing the feces of infected fleas into the skin or when infected excrement comes into contact with the conjunctiva (0.01 mg is sufficient);
- airborne - when dried flea excrement enters the respiratory tract;
- alimentary - when eating food contaminated with the urine of infected animals;
- transmissible - through the bites of ticks that parasitize rodents and are capable of transovarial transmission.
The disease is not transmitted from person to person. The maximum incidence is observed in the autumn-winter period, when rodents move into human dwellings. The disease is registered mainly among people living in houses where there are rodents, as well as among workers in warehouses, grocery stores, etc.
Human susceptibility is high.
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Spread of endemic typhus
Flea-borne typhus is found in port cities of North and South America, India, Australia, the Mediterranean basin and other regions where a large number of rodents (rats, mice) live. Sporadic cases are recorded on the coasts of the Black, Caspian and Japanese seas.
What causes endemic typhus?
Endemic typhus is caused by Rickettsia mooseri, which multiply in the cytoplasm of affected cells. In its morphological, biological and antigenic properties, it is very close to Rickettsia prowazekii, but has less pleomorphism. They have a common thermostable antigen and cross-react with sera of patients with typhus. Serological differentiation is based on the detection of a species-specific thermolabile antigen. Among laboratory animals, rats, mice and guinea pigs are sensitive to the pathogen. In the environment at low temperatures, Rickettsia mooseri in a dried state in flea excrement and rodent secretions can remain viable for a long time.
Pathogenesis of endemic typhus
Animal experiments have shown that the basis of pathogenesis and morphological substrate of the disease, as in typhus, is destructive-proliferative thrombovasculitis of capillaries, precapillaries and arterioles with the formation of granulomas at the site of rickettsia parasitism. However, all processes are less pronounced and prolonged. The allergic component is one of the significant factors in the pathogenesis of endemic typhus, which is expressed in the predominantly papular nature of the rash. After suffering rat rickettsiosis, persistent homologous immunity develops.
Symptoms of endemic typhus
Endemic rat typhus has an incubation period of 5-15 days (on average 8) days. The onset of the disease is usually acute, symptoms of endemic rat typhus appear: chills, headache, fever, muscle and joint pain. Fever reaches a maximum (38-40 °C) by the 4th-5th day of illness, without the use of antibiotics it lasts up to 2 weeks and decreases by accelerated lysis. The temperature curve of a constant type predominates, less often remittent or irregular.
On the 4th-7th day of the disease, 75% of patients develop a polymorphic roseola or roseola-papular rash, most abundant on the body. Unlike epidemic typhus, elements can appear on the face, palms and soles. Another feature of the rash is the transformation of most roseola elements into papules after 2-3 days. Petechial elements are possible only in severe cases of the disease (10-13% of cases). There are no rashes.
Changes in the cardiovascular system are minimal, bradycardia and moderate arterial hypotension may be observed. Nervous system damage in most patients is insignificant - in the form of dizziness and general weakness. Meningeal signs, psychosis, Govorov-Godelye symptom, typhoid status do not occur. Liver and spleen enlargement is possible in 30-50% of patients.
Endemic murine typhus usually proceeds favorably, without relapses. Complications (thrombophlebitis, otitis, pneumonia) are very rare.
Diagnosis of endemic typhus
Clinical and differential diagnostics of endemic murine typhus is very difficult. It is necessary to take into account the epidemiological situation and the presence of roseolous and papular rash not only on the skin of the trunk and extremities, but also on the face, palms and feet.
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Specific and non-specific laboratory diagnostics of endemic typhus
The hemogram initially reveals leukopenia, then leukocytosis with lymphocytosis; an increase in ESR is possible.
Specific diagnostics of endemic murine typhus (standard diagnostics) - RSK and RNGA. Given the antigenic similarity of Rickettsia mooseri and Rickettsia prowazekii, the reactions are carried out in parallel. A clear predominance of the antibody titer in the reaction with the R. mooseri antigen compared to the R. prowazekii antigen confirms the diagnosis of endemic typhus. Rarely, mainly with the same antibody titers to both species, a biological test is used (scrotal phenomenon).
What tests are needed?
How is endemic murine typhus treated?
Treatment of endemic rat typhus is carried out according to the general principles of management of patients with rickettsioses. Patients are hospitalized according to clinical indicators. No special diet is required. Bed rest is required until the temperature is normalized. Doxycycline is prescribed (0.5 g twice a day on the first day, then once a day) or tetracycline (0.3 g four times a day), and in case of its intolerance - chloramphenicol (0.5 g four times a day) up to the second day of normalization of temperature inclusive (usually 4-5 days). With timely use of antibiotics, pathogenetic and symptomatic treatment of endemic rat typhus is carried out in a minimal volume.
Rules of discharge
Convalescents are discharged after complete clinical recovery.
Clinical examination
No medical examinations are carried out.
How to prevent endemic murine typhus?
Endemic murine typhus is not contagious and does not require mandatory hospitalization. Preventive measures in the outbreak are primarily aimed at controlling rodents (deratization). Disinfection is also carried out. There is no specific prevention.