Tick-borne rickettsiosis

Description:

Tick-borne rickettsiosis (tick-borne sapropyra of Northern Asia) - the benign ostrolikhoradochny disease from group of zoonoz which is characterized by existence of primary affect in the place of suction of a tick and makulopapulezny rash.

The tick-borne rickettsiosis is described in Eastern Siberia and in the Far East (Seaside, Khabarovsk, Krasnoyarsk regions, the Chita and Irkutsk regions, Buryatia and Tuva), in Western Siberia (The Kemerovo, Tomsk, Novosibirsk, Omsk, Tyumen, Kurgan regions, Altai Krai), Azerbaijan, Kazakhstan, Turkmenistan, Tajikistan, Kyrgyzstan and Armenia, in the Mongolian People's Republic and Pakistan. In the European part of the USSR (The Tula and Kharkiv regions, Bashkiria and Lithuania) circulation of the activator in the antropurgichesky centers is established, diseases of people are not described.

Symptoms of the Tick-borne rickettsiosis:

The incubation interval fluctuates from 2 to 7 days, is mostly equal to 3-6 days. In the place of suction of a tick morbidity, a hyperemia and small infiltrate with a necrotic crust in the center, increase in regional lymph nodes develops. Small weakness, chilling, an ache in joints, a loss of appetite can be noted. The beginning of a disease acute, at a part of patients observe a prodromal stage in which the general weakness and weakness, pain and an ache in muscles, bones, joints, a waist, small temperature increase, catarral changes in a drink and upper respiratory tracts are described. In this period primary affect is already expressed. According to aggregated data of M. M. Lyskovtsev (1963), primary affect is found at 76,6% of patients, is more often at adults (80,1%), than at children (67,2%). Its localization is various: on a trunk (38%), the head (21%), the lower extremities (21%), is more rare - on a neck (9,6%) and upper extremities (7,4%).
For the 2-3rd day of a prodrome the clinical picture of a disease fever, a headache, sleeplessness, a fever, an ache and all body pains develops, there can be nausea and vomiting. Duration of fever-3-18 days, on average 8 days. For the 2-4th day of a disease rash develops. It is a characteristic sign of a tick-borne rickettsiosis, and its early emergence facilitates clinical diagnosis. The histology of rash is similar to typhous. Rashes begin with extremities, existence of rash on palms and soles is characteristic. Rash during 1,5-2 days extends to a trunk, sometimes and to the person. Has an appearance of large roseolas and papules of bright pink color. The sizes vary from small elements size about a pin head to large, 2-3 mm in size in the diameter. Sometimes rash passes into petekhialny. Are typical localization of rash on extensor surfaces and its abundance on the lower extremities. Observe slow fading of rash and existence of pigmentation on site of its disappearance. The changes from cardiovascular system which are expressed in bradycardia and lowering of arterial pressure are most characteristic. Changes of a nervous system consist in a sharp headache, mialgiya, arthralgias, a sleep disorder and appetite.

During the feverish period normokhromny anemia with reduction of quantity of erythrocytes and hemoglobin by 10-15% is observed. Also decrease in number of thrombocytes is noted. At the beginning of a disease note a lymphopenia. In a leukocytic formula note neutrophylic reaction with regenerative and degenerative shift.
Pathognomonic sign of a tick-borne rickettsiosis is development of primary complex including primary affect and regional lymphadenitis.

Reasons of the Tick-borne rickettsiosis:

The causative agent of a disease-Rickettsia sibirica belongs to rickettsiae of group of tick-borne spotty fever and on an antigenic structure is closest to a group-R prototype. to rickettsii, causative agent of the spotty fever of the Rocky Mountains widespread in the Western hemisphere. R. sibirica, as well as others of rickettsiae, is a gram-negative bacterium with obligate intracellular parasitism, does not grow on artificial mediums, breeds in the live and worrying tissues of hematothermal animals and in an organism of ixodic mites. The usual environment of cultivation - chicken embryos or culture of cells. A model laboratory animal - a Guinea pig. R. sibirica differs in polymorphism, rod forms prevail. Intranuclear and cytoplasmatic localization is characteristic. It is painted by aniline dyes (fuchsin) in pink color by Romanovsky's methods - Gimza, Zdrodovsky, Gimenyes. The structure of the bases of DNA, as well as at all representatives of group, is equal to 32,5 (Tm) of mol. It is unstable in external environment.

Source and carrier of a contagium - ixodic mites of the sorts Dermacentor, Haemaphysalis, Ixodes. The main carriers - D. nuttalli, D. tnarginatus, D. pictus, D. silvarum, H. concinna, H. punctata. At mites transphase and transovarial transfer of the activator is established. An additional tank of R. sibirica in the nature are prokormitel of ixodic mites - small mammals (rodents, insectivorous), wild hoofed animals and farm animals.
The pathogeny of a tick-borne rickettsiosis is caused both by the transmissible nature of transfer of the activator, and R.sibirica properties. Rickettsiae get into a human body as a result of suction of a tick. The activator breeds in the place of suction (entrance gate of a contagium) where primary affect is formed. The lymphogenous drift of a contagium occurs when rickettsiae with lymph current on lymphatic ways get into a regional lymph node in which cause inflammatory reaction lymphangitis and lymphadenitis. The exudative process which arose in the place of suction within 3-4 days is replaced proliferative, changes in absorbent vessels have destructive and proliferative character. From a lymph node of a rickettsia get into blood where the rikketsiyemiya and a toxaemia develops. Diffuzno is surprised vascular system from a blood stazama in capillaries and formation of granulomas. The leading value in a pathogeny has defeat of a nervous system - brain vessels.
The person at a tick-borne rickettsiosis is "the biological deadlock" for the activator.

Natural medium of existence of R.sibirica in the natural and antropurgichesky centers - an organism of ixodic mites and their prokormitel. The natural rikketsionositelstvo is established at ixodic mites almost in all centers.

Except ixodic, the natural carriage of R.sibirica is revealed at gamazovy mites of Dermanyssus hirundinis (The Kokchetav Region), Nothrholaspis sp. and Ilirstionyssus myospalacis (The East Kazakhstan Region), Ilirstionyssus isabcllinus and Haemolaelaps glasgowi (Primorsky Krai), Ilirstionyssus ellobii (The Kokchetav, Tselinograd Region), Ilirstionyssus criceti (The Kokchetav Region), krasnotelkovy mites of Trombicula autumnalis and Trombicula zachvatkini (The Kokchetav Region), fleas of Neopsylla pleskei in Khakassia.
The listed arthropods do not play an epidemiological role, and, apparently, carry out circulation of R.sibinca in the centers.

Treatment of the Tick-borne rickettsiosis:

Patients with a tick-borne rickettsiosis are hospitalized in infectious departments of hospitals, and in the absence of those - in therapeutic departments. In the acute period the bed rest is necessary for patients.
Treatment is carried out by antibiotics of a tetracycline row (tetracycline, Oxytetracyclinum).
The dosage of tetracycline and duration of treatment are defined depending on disease severity and age of the patient. The adult tetracycline or its derivatives are appointed inside on 0,2 g in 6 hours. In general the course of treatment of patients proceeds usually no more than 5 days. The general course dose makes 4-5 g of tetracycline.
Use of tetracycline drugs, as a rule, in 24-36 hours and less often in 48 hours from an initiation of treatment leads to considerable improvement of the general condition of patients. Prescription of antibiotics is stopped usually in 2 days after normalization of temperature.
At an initiation of treatment duration of the feverish period is reduced by antibiotics for the 3-5th day of a disease to 5-8 days.
Along with causal treatment the pathogenetic and symptomatic treatment is carried out.
At sharply expressed intoxication phenomena, especially at patients of advanced age, intravenously enter 40-% solution of glucose on 20 ml with 5 percent ascorbic acid on 2 ml. Also intravenous or hypodermic injection of 5-% solution of glucose is shown. Detection of signs of defeat of cardiovascular system is the indication for purpose of angiotonic drugs: ephedrine, adrenaline, caffeine, etc. For simplification of a headache it is recommended to appoint pyramidon, antipyrine, and at sleeplessness - valerian drugs, bromides, barbiturates.
Considering the observed changes from cardiovascular system at patients with a tick-borne rickettsiosis and slow recovery of a vascular tone, the bed rest within 5 days of normal temperature, and an extract - not earlier than the 10th day from the beginning of an apireksiya is shown to patients.