Rickettsial diseases – the numerous infectious diseases connected by an etiology community (activators – rikketsiya) and epidemiology (have mainly inoculable mechanism of transfer). Rickettsial diseases proceed with emergence of primary affect (at tick-borne rickettsial diseases), feverish and intoksikatsionny syndromes, generalized vaskulita and skin rashes. To confirm the diagnosis of a rickettsial disease and to verify its clinical form serological diagnostics (RIGA, RSK, RNIF, IFA) allows. Etiotropny therapy of rickettsial diseases is carried out by antibacterial medicines from group of tetratsiklin and chloramphenicol.
Rickettsial diseases – the term used concerning the inoculable feverish diseases caused by intracellular activators — rikketsiya. The group of rickettsial diseases of the person includes sypny typhus (endemic and epidemic), tick-borne fevers (spotty fever of the Rocky Mountains, the Volynsk fever, the Marseilles fever, a vezikulezny rickettsial disease, a North Asian tick-borne rickettsial disease), paroksizmalny rickettsial diseases (trench fever, a tick-borne paroksizmalny rickettsial disease), fever of a tsutsugamusha and Ku's fever. Despite etiologichesky distinctions, some general epidemiological, pathogenetic, patomorfologichesky, immunological and clinical signs allowing to unite them the general name – rickettsial diseases are peculiar to all these diseases. Prevalence of rickettsial diseases universal; the greatest incidence is noted in developing countries where in structure of fevers of not clear etiology they make 15-25%.
Reasons of rickettsial diseases
On the cultural qualities rikketsiya are an intermediate link between bacteria and viruses. With microbic activators they are pulled together by morphological features (gramotritsatelny rhabdoid or kokkovidny forms), and with virus agents – ability to intracellular parasitizing. For the person the following types of rikketsiya (Rickettsia) are pathogenic:
- R. Prowazekii – causes epidemic (lousy) sypny typhus and its remote recurrence - Brill's disease
- R. Typhi – causes endemic (rat, flea) sypny typhus
- R. Sibirica – causes a North Asian tick-borne rickettsial disease
- R. Conorii – causes the Marseilles fever
- R. Rickettsii – causes spotty fever of the Rocky Mountains
- R. Australis – causes the Australian tick-borne rickettsial disease
- R. Quintana (Rochalimea quintana) – causes the Volynsk (trench) fever
- R. Akari – causes an ospovidny (vezikulezny) rickettsial disease
- R. Japonica — causes the Japanese spotty fever
- R. Orientalis – causes tsutsugamush
- R. Burneti (Coxiella burnetii) – Ku fever causes
Rickettsial diseases share on antroponozny at which as sources of an infection the person, and carriers – louses, and zoonozny, characterized by transfer from animals through stings of pincers acts. Typhus and trench fever belong to antroponoza sypny; to natural and focal zoonoza – all other rickettsial diseases.
In the external environment of a rikketsiya are not steady: for them heating and influence of disinfectants are pernicious. However at low temperatures and drying of a rikketsiya can remain a long time. Possibly several ways of infection of the person with a rickettsial disease – inoculable, haemo transfusion and transplacentary; in certain cases (for example, at Ku's fever – contact, aspiration, alimentary). As entrance gate for rikketsiya most often serve integuments where in the place of introduction of the activator local inflammatory reaction - primary affect can develop. The subsequent hematogenic dissemination of the activator causes development feverish a syndrome and a generalized vaskulit.
Symptoms of rickettsial diseases
Rickettsial diseases of group of a typhus
Epidemic (lousy) sypny typhus proceeds with fever, intoxication, rozeolezno-petekhialny rash on skin, defeat of vascular and nervous system. The incubatory period takes from 5 to 21 days. The rickettsial disease demonstrates from temperature increase of a body and obshcheintoksikatsionny symptoms which reach the maximum expressiveness to the 3-6th put diseases. During this period the expressed hyperaemia and puffiness of the person, an injection a skler, an enantem on a soft palate is noted. Approximately for the 5th days on skin of a side surface of a breast, a stomach, the sgibatelny surfaces of hands bright characteristic rozeolezno-petekhialny rash develops. In a week rash turns pale, and on the 2-3rd week from the beginning of a disease disappears. At the same time temperature decreases and intoxication disappears, however some more weeks remain a post-infectious adynamy. At the heavy course of a rickettsial disease arises defeat of TsNS in the form of meningitis or encephalitis. Complications of an epidemic typhus can include otitis, parotitis, pneumonia, myocarditis. Bril's disease, or the typhus recuring sypny, is shown by the same symptoms which however were less expressed.
Endemic (rat or flea) sypny typhus begins sharply and in an initial stage is characterized by all-infectious symptoms (fever, a poznablivaniye, artralgiya, a headache). At the height of the feverish period on a breast, a stomach and on extremities there is a rash having mainly rozeolezno-papular character. Arterial hypotonia, bradycardia, the general weakness, dizziness is characteristic. In general the disease proceeds easier, than epidemic sypny typhus.
Rickettsial diseases of group of spotty tick-borne fevers
The North Asian tick-borne rickettsial disease, or tick-borne sypny typhus of Northern Asia is transmitted through stings of ixodic pincers. Primary affect – primary inflammatory reaction of skin in the place of penetration of the activator is a typical sign of a tick-borne rickettsial disease. It represents the painful consolidation surrounded with a zone of hyperaemia and in the center covered with a brown scab. Along with emergence of primary affect body temperature increases, regionarny lymphadenitis and an intoksikatsionny syndrome develops. Skin rashes develop for the 2-3rd day and are presented by the polymorphic rozeolezno-papular elements located on a trunk and around joints. Hyperaemia of the person and mucous a pharynx, bradycardia, hypotonia, a moderate gepatosplenomegaliya is noted. Course of a North Asian tick-borne rickettsial disease good-quality; usually by 14th day of a disease there occurs recovery.
The Marseilles fever is also characterized by existence of primary affect in the place of introduction of a tick, fever, lymphadenitis, spotty and papular rash. Initial symptoms of a rickettsial disease are similar to a tick-borne typhus of Northern Asia. Primary affect looks as dense infiltrate with the central necrosis which izjyazvlyatsya and epitelizirutsya further only in the convalescence period (in 3-4 weeks). Against the background of a feverish intoksikatsionnykh of manifestations hyperaemia of a mucous rotoglotka, a sore throat, conjunctivitis are expressed. The Marseilles fever is characterized by rash which affects not only a body, but also a face, palms and soles. Usually rash has spotty and papular character, but can be transformed to spots ("pryshchevidny fever") with hemorrhagic contents. Fading of rash gradual, on its place is long pigmentation remains.
Spotty fever of the Rocky Mountains belongs to rickettsial diseases with a heavy current. In the sharp period the disease is followed by the fever which is replaced by heat; severe head and muscular pain, nasal bleedings. Neurologic changes include sleeplessness, consciousness violation (an oglushennost, prostration), spasms, couple - and a hemiplegia, violation of sight and hearing. Primary affect is absent. Rash at this type of a rickettsial disease plentiful, petekhialny, tends to merge to formation of big spots. The lethality from this rickettsial disease reaches 7%.
Paroksizmalny rickettsial diseases
Paroksizmalny rickettsial diseases proceed with the recidivous feverish attacks repeating each 5 days (at the Volynsk fever) or 2-3 days (at a paroksizmalny tick-borne rickettsial disease). During an attack temperature increases to 39,0–40,5 °C, there are oznoba, ossalgiya, mialgiya, artralgiya, headaches. Primary affect, skin rashes and regionarny lymphadenitis are not constant satellites of paroksizmalny rickettsial diseases and often are absent. Course of fevers usually long, however good-quality.
Diagnostics and treatment of rickettsial diseases
Identification and differential diagnosis of rickettsial diseases is carried out in several directions: collecting the epidemiological anamnesis, analysis of clinical data and laboratory verification of the activator. In the epidemiological status the emphasis is placed on the natural and focal nature of an infection, communication of a disease with stings of pincers, a pediculosis etc. In the analysis of clinical symptomatology of rickettsial diseases the main attention is paid to existence of primary affect, character and localization of rash.
Laboratory diagnosis of rickettsial diseases is carried out by means of the serological methods (RSK, RA, RIGA, RIF, IFA) allowing to identify the activator by definition of its anti-genes and specific antibodies. In some cases allocation of rikketsiya from blood, urine, cerebrospinal fluid, bioptat, biomass of pincers, conducting skin and allergic tests is possible. Differential diagnosis of rickettsial diseases is carried out with flu, measles, hemorrhagic fevers, a meningococcal infection, a typhoid, an enteroviral infection, an allergy, etc.
As means of etiotropny therapy of a rickettsial disease antibiotics of a tetracycline row (, doxycycline), chloramphenicol, ftorkhinolona are used. Usually the course of treatment proceeds all feverish period and 2-3 days after normalization of body temperature. The dezintoksikatsionny, desensibilizing, anti-inflammatory therapy is at the same time carried out. At the heavy course of rickettsial diseases kortikosteroidny hormones are applied.
Forecast and prevention of rickettsial diseases
On a current, outcomes and percent of a lethality typhus, spotty fever of the Rocky Mountains and a tsutsugamusha belong to the heaviest rickettsial diseases epidemic sypny. Other rickettsial diseases proceed is more good-quality and seldom are followed by complications. Prevention of infection with rickettsial diseases provides fight against a pediculosis, pincers and rodents, observance of measures of personal protection against attack of blood-sicking insects. At stings of pincers performing the emergency chemoprophylaxis by doxycycline or azitromitsiny is recommended. For the purpose of prevention of a typhus and Ku's fever vaccination is carried out. Patients with a typhus are subject to strict isolation; behind the persons contacting to the patient observation is established; in the center of an infection sanitary processing is carried out.