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Endemic rat typhus: causes, symptoms, diagnosis, treatment
Last reviewed: 23.04.2024
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Endemic typhus is a sporadic acute benign zoonotic rickettsiosis transmitted through ectoparasites of mice and rats, with characteristic cyclic course, fever, mild intoxication and a common rosaceous-papular rash.
Synonyms: rat typhus, rat rickettsiosis, flea typhus, flea rickettsiosis, Mediterranean rat rickettsiosis, Manchu epidemic typhus.
ICD-10 codes
- A79. Other rickettsiosis.
- A79.8. Other specified rickettsiosis.
Epidemiology of endemic typhus
The source and natural reservoir of infectious agents are rodents (rats and mice), their ectoparasites (fleas and gamma mites).
A person from infected rodents gets infected in the following ways:
- contact - when rubbing the feces of infected fleas into the skin or when infected feces fall on the conjunctiva (0.01 mg is enough);
- aerogenic - when dry feces fall into the respiratory tract;
- alimentary - when eating food contaminated with urine from infected animals;
- transmissible - through the bites of mites, parasites on rodents and capable of transovarial transmission.
From person to person, the disease is not transmitted. The maximum incidence is noted in the autumn-winter time, when rodents move to people's homes. The disease is mainly registered among individuals. Living in houses where there are rodents, and also among workers of warehouses, food shops, etc.
The susceptibility of a person is high.
Distribution of endemic typhus
Flea typhus is found in the port cities of North and South America, India, Australia, the Mediterranean basin and other regions. Where there is a large number of rodents (rats, mice). 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 rickettsia , which multiply in the cytoplasm of the affected cells. Due to its morphological, biological and antigenic properties, it is very close to the rivets of Prowacek, but has a smaller pleomorphism. They have a common thermostable antigen and give cross reactions with sera in patients with typhus. Serological differentiation is based on the identification of a species-specific thermolabile antigen. Among laboratory animals, rats, mice, guinea pigs are sensitive to the causative agent. In the environment at low temperatures, the Micker rickettsia in the dried state in flea feces and rodent secretions can remain viable for a long time.
Pathogenesis of endemic typhus
In the animal experiment it was shown that the pathogenesis basis and the morphological substrate of the disease, as well as with typhus, are destructive-proliferative thrombovasculitis of capillaries, precapillaries and arterioles with the formation of a granule at the site of rickettsia parasites. However, all processes are less pronounced and prolonged. The allergic component is one of the essential factors in the pathogenesis of endemic typhus, which is expressed in the predominantly papular nature of the rash. After the transferred rickettsiosis rats develop a stable homologous immunity.
Symptoms of endemic typhus
Endemic rat typhus has an incubation period of 5-15 days (an average of 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 4-5th day of the disease, without the use of antibiotics it persists up to 2 weeks and is reduced by accelerated lysis. The temperature curve is of a constant type, less often remittent or irregular.
On the 4th-7th day of the disease in 75% of patients appears a polymorphous roseous or rose-papular rash, most abundant on the trunk. Unlike epidemic typhus, elements can appear on the face, palms and soles. Another feature of the rash is the transformation of most of the roseous cells in 2-3 days into papules. Petechial elements are possible only in severe disease (10-13% of cases). There is no dropsy.
Changes in the cardiovascular system are minimal, bradycardia and mild arterial hypotension may occur. The lesions of the nervous system in most patients are insignificant - in the form of dizziness and general weakness. Meningeal signs, psychoses, Govorov-Godel's symptom, there is no typhoid status. Enlargement of the liver and spleen is possible in 30-50% of patients.
Endemic rat typhus usually proceeds favorably, without recurrence. Complications (thrombophlebitis, otitis media, pneumonia) are very rare.
Diagnosis of endemic typhus
Clinical and differential diagnosis of endemic rat typhus is very difficult. It is necessary to take into account the epidemiological situation and the presence of rose and papular rash not only on the skin of the trunk and extremities, but also on the face, palms and feet.
[10], [11], [12], [13], [14], [15]
Specific and nonspecific laboratory diagnostics of endemic typhus
In the hemogram, first, leukopenia, then leukocytosis with lymphocytosis; possibly an increase in ESR.
Specific diagnosis of endemic rat typhus (diagnostic standard) - RSK and RNGA. Considering the antigenic similarity of Rickettsiae Muser and Riquettsia Prowacek, reactions are put in parallel. The distinct predominance of antibody titer in the reaction with R. Mooseri antigen in comparison with R. Prowazekii antigen confirms the diagnosis of endemic typhus. Rare, mainly with the same titres of antibodies to both species, use a biological sample (scrotal phenomenon).
What tests are needed?
How is endemic rat typhus treated?
Treatment of endemic rat typhus is carried out according to the general principles of management of patients with rickettsiosis. Patients are hospitalized according to clinical indices. A special diet is not required. Before the normalization of temperature, the bed conditions. Assign doxycycline (the first day of 0.5 g twice a day, then once a day) or tetracycline (0.3 grams four times a day), and with its intolerance - chloramphenicol (0.5 g four times per day) until the second day of temperature normalization (usually 4-5 days). With the timely use of antibiotics, the pathogenetic and symptomatic treatment of endemic rat typhus is carried out in a minimal amount.
Statement rules
Convalescents are discharged after complete clinical recovery.
Clinical examination
Do not spend the dispensary.
How to prevent endemic rat typhus?
Endemic rat typhus is not contagious and no mandatory hospitalization is needed. Preventive measures in the outbreak center are primarily aimed at fighting rodents (deratization). Disinfection is also carried out. There is no specific prevention.