Q fever
Description:
Q fever - a zoonotic acute rickettsiosis with development of a reticuloendotheliosis, intoxication syndrome, it is frequent with atypical pneumonia.
The name "Q-fever" (from English queri - not clear) was offered by E. Derrick who for the first time described a disease at farmers and working meat factories in Australia (1937). The rickettsial nature of a disease was established by F. M. Burnett and M. Freeman (1939). Irrespective of the Australian researchers in the USA X. Coke allocated the filtered agent from mites carriers of fever of the Rocky Mountains and proved his rickettsial nature (1938). Later the activator was allocated in the separate sort of rickettsiae called in his honor. In Russia the centers of a disease are known since 1952 and are widespread everywhere; in the sixties the 20th century they were studied by P.F. Zdrodovsky, M. P. Chumakov, E. N. Bartashevich, etc.
Q fever symptoms:
Incubation interval. Varies from 3 to 30 days, sometimes it drags on up to 3 months. Allocate acute, subacute and chronic forms of the Q fever of varying severity. Most often the acute form of a disease meets damage of lungs.
The disease begins, as a rule, with bystry, within 1-2 days, fervescence till 39-40 "With, however the beginning can be and gradual.
Initial stage. Several days last, note oznoba, perspiration, the expressed weakness, a headache with preferential localization in orbits of eyes, a mialgiya and an arthralgia, sleep disorders. At a heavy current of the Q fever there can be an excitement, sleeplessness, a delirium. At the acute beginning of a disease often note a hyperemia of the person and neck, an injection of vessels of scleras, a conjunctiva and a mucous membrane of a stomatopharynx, a razrykhlyonnost and a hypertrophy of almonds, enanty on a soft palate. In cases of a gradual onset of the illness integuments can be pale. Occasionally (1-4% of cases) there is a dieback, usually rozeolyozny or spotty and papular character. Pathology from a respiratory organs during the first days of a disease usually does not develop. Cardiac sounds are muffled, do not observe characteristic changes of pulse.
Heat period. The main complaints of patients remain. High temperature keeps on average to 1 week, but sometimes after that fever drags on on subfebrile sizes for 7-8 days then there comes the second wave of temperature increase. In similar cases the general duration of fever makes 2-3 weeks and more; the typical temperature curve is uncharacteristic.
Note relative bradycardia, a priglushyonnost of cardiac sounds, moderate arterial hypotension. Only during this period clinical signs from a respiratory organs in the form of bronchitis or tracheitis begin to be shown. However already at this time at radiological inspection it is possible to find strengthening of the pulmonary drawing and melkoochagovy cone-shaped infiltrates which are localized preferential in lower parts easy or radical zones. The last sometimes merge with formation of massive blackouts of pulmonary fabric, but without formation of cavities. Increase in peribronchial lymph nodes creates a picture of expansion, consolidation and deformation of roots of lungs. With development of pneumonia in patients dry, and then wet cough with allocation of a serous and purulent phlegm, occasionally with blood impurity amplifies. There is short wind, the insignificant thorax pains amplifying at damage of a pleura are possible. Physical data in comparison with radiological changes scanty: reveal sites of shortening of a percussion sound and rigid breath, a small amount of dry or wet small-bubbling rattles in lungs. The course of pneumonia torpid, radiological changes disappear slowly.
In cases with the expressed intoxication nausea and vomiting are possible, appetite sharply decreases. Owing to damage of the autonomic nervous system sometimes patients have non-constant abdominal pains and a meteorism. Language resembles that at a typhoid superficially: edematous, is laid over by a dirty-gray plaque, with pure edges and a tip, and also prints of teeth at the edges. Moderate increase in a liver and spleen is characteristic.
Reconvalescence period. It is shown by decrease in body temperature within 2-4 days, improvement of health and a condition of patients, obsolescence of the main clinical signs of a disease. The physical and mental adynamy is usually characteristic of this period.
In addition to acute cyclic the Q fever can be shown in a subacute form lasting from 1 to 3 month or in a chronic form lasting from several months till 1 year and more. In these cases the disease proceeds against the background of subfebrile condition with the radiological expressed infiltrative processes in lungs.
The provided description of the Q fever gives the chance to the doctor to suspect a disease on the basis of kliniko-epidemiological data. At the same time displays of a disease are very various and can be expressed in the form of grippopodobny, lozhnobrutsellyozny, pseudotuberculous, septic and other clinical options. In these cases statement of the clinical diagnosis is difficult without special methods of laboratory diagnosis.
Q fever reasons:
The activator - small gram-negative, is more often rhabdoid bacteria of Coxiella burnetii of the sort Coxiella the mushrooms of Rickettsieae of the Rickettsiaceae family also known as Burnett's rickettsiae. Microorganisms are inclined to polymorphism and formation of L-forms. The main properties are similar to those of other rickettsiae; their main difference - high stability in the environment (in wool, cotton, straw, etc.). Keeps heating to 90 °C during 1 h in milk, in excrements of mites, dry substrates, sterile milk, to not chlorinated water at 4 °C keeps viability over a year, in meat - more than a month. Burnett's rickettsiae of a rezistentna to action of ultra-violet radiation, solutions of formalin, phenol and chloric lime in usual concentration. High stability is defined by ability to create sporogenous forms. Phase variability with formation of the forms similar to S-and R-forms of bacteria is characteristic of them. Svezhevydelenny bacteria possess antigens of 1 phase, but after long resowings on chicken embryos are transformed to the II phase. This dissociation has reversible character, and after infection of animals a set of antigens is recovered. Bacteria of the II phase are inclined to spontaneous agglutination, are agglutinated by normal serum and come to light in RSK. Antigens I of a phase show a big immunogenicity, and the formed antibodies react with antigens of both phases. Antigens II of a phase induce antibody formation, reacting only with phase antigens II.
Treatment of the Q fever:
As means of causal treatment apply tetracyclines (tetracycline on 1,2-1,6 g/days, doxycycline on 200 mg/days) or levomycetinum in a dose of 2 g/days inside. The most effectively parenteral administration of a combination of tetracycline with levomycetinum on 0,9 and 1,5 g/days respectively. Duration of a course of treatment defines clinical effect of drugs and averages 8-10 days. Shortening of a course or decrease in doses of drugs promotes emergence of a recurrence. It is long the remaining radiological changes in lungs are not the indication to prolongation of causal treatment. At the same time carry out disintoxication therapy, appoint desensibilizing and non-steroidal anti-inflammatory drugs (indometacin, Butadionum, Ortophenum, diclofenac, etc.). At severe long and chronic forms in addition appoint glucocorticoids (Prednisolonum on 30-60 mg/days, dexamethasone on 4-5 mg/days).
