Epidemic typhus

Typhus is an acute anthroponotic rickettsiosis with a transmissible mechanism of transmission of the pathogen, capable of mass dissemination. This disease is characterized by a severe cyclic course, the development of generalized vasculitis, rose-petechial rash and the primary lesion of the nervous and cardiovascular system.

Two distinct forms of typhus are distinguished and recorded separately:

• epidemic (fecund) typhus;
• recurrent typhus (Brill disease).

Epidemic typhus has the following synonyms: historical, head, typhus typhus, war, typhoid fever, prison fever, camp fever; typhus exanthematicus (lat.); epidemic typhus fever.

ICD-10 code

A75.0. Epidemic typhus.

What causes epidemic typhus?

Epidemic typhus (European, classical, licefied typhus, prison fever) is caused by Rickettsia Provachek. Symptoms of epidemic typhus are long and include a high fever, an unrestrained headache and a patchy-papular rash.

A person is a natural reservoir of R. Prowazekii, which is worldwide prevalent and is transmitted by lice when their feces are rubbed into the place of bite or into the place of other skin damage (sometimes conjunctiva of the eyes or oral cavity). In the United States, in rare cases, people can become infected with epidemic typhus after contact with a flying squirrel.

The mortality from this disease among children under 10 years is low, but its level increases with age and can reach 60% among untreated patients over the age of 50 years.

What are the symptoms of epidemic typhus?

Epidemic typhus has an incubation period of 7-14 days. After it, a sudden fever, headache and prostration. Within a few days the temperature reaches 40 C and remains high. Minor morning temperature drops are noted. The duration of the febrile period is about 2 weeks. Headache has a generalized nature and high intensity. On the 4th-6th day of the disease, typical symptoms of epidemic typhus appear: small pink maculae, which quickly cover the body, usually starting from the upper part of the trunk and axillary depressions. In most cases, the rash does not appear on the palms, soles and face. Later the rash darkens and becomes maculopapular. In the case of acute disease, the rash becomes petechial and hemorrhagic. In some cases, splenomegaly can be detected. Hypotension occurs in the most severe patients. Poor prognostic signs are vascular collapse, renal failure, signs of brain damage, ecchymosis with gangrene and pneumonia.

How is epidemic typhus diagnosed?

Epidemic typhus must be differentiated with other acute infections, primary meningococcemia, measles and rubella. Information on contact with lice, tick bite or presence in an endemic region may be useful for diagnosis, but often such information can not be obtained. Clinical signs can help to distinguish diseases.

In the subacute form of meningococcemia, the rash may be pink, spotty, spotty-papular or petechial. In the fulminant form of meningococcemia, the rash may be petechial-draining or ecchymic (hemorrhagic). In the acute form of the disease, the rash appears quickly, and in the case of an ecchymosis rash, the elements are usually sensitive to palpation.

With measles, the rash first appears on the face, spreads to the trunk and hands and soon becomes drained. Rashes with rubella usually do not merge. The increase in the behind-the-back lymph nodes and weak intoxication speak for rubella.

Diseases caused by rickettsia and similar microorganisms should also be differentiated. In view of the fact that many of the rickettsia are common in certain geographic regions, information about the place of residence and recent travel may be useful in terms of diagnosis. Whatever it was, it usually requires special research. The most significant studies for the detection of Rickettsia rickettsii are indirect immunofluorescence (ELISA) and a PCR study of the biopsy material of the rash. The culture test is difficult to perform and has no clinical significance. For the detection of Ehrlichia, the best method of investigation is the PCR of the blood. Serological diagnosis does not allow to diagnose an acute disease, since they become positive only by the time of recovery.

How is epidemic typhus treated?

Primary treatment of epidemic typhus includes doxycycline at a dose of 200 mg orally 1 time, after which the drug is prescribed at a dose of 100 mg 2 times a day until clinical improvement and no fever within 24-48 hours. Treatment of epidemic typhus with doxycycline should last no less than 7 days. The second line of treatment is the administration of chloramphenicol in a dose of 500 mg orally or intravenously 4 times a day for 7 days.

How to prevent epidemic typhus?

The presence of lice is usually obvious and should lead to the thought of typhus. Epidemic typhus can be prevented by combating lice and immunization. In the US, these vaccines are not available. Lice can be eliminated by spraying infected people with carbofos or dan.

Prevention of the introduction of ticks into the skin includes walking specially designed trails in the forest, filling the pants in boots or socks, wearing long-sleeved shirts in the forest, and using drugs that repel insects such as diethyltoluamide. These drugs should be used with caution in young children, since there are reports of toxic reactions. Permethrin, applied to clothing, effectively kills mites. For prevention, good personal hygiene skills are required, often searching for ticks, especially on the hairy areas of the body and in children. Saturated ticks should be carefully removed. The squeezing of the mite between the fingers is unacceptable, since it contributes to the spread of the infection. The body of the mite should not be squeezed. Remove mites should be gradual traction by the head, which is done with a small tweezers. The place of bite should be wiped with alcohol. Vaseline oil, alcohol and any other irritants are ineffective, and therefore should not be used.

There are no ways to cleanse the whole region of ticks, but ticks populations can be reduced in endemic regions by controlling the population size of small animals.