Astrakhan rickettsial fever: causes, symptoms, diagnosis, treatment

Astrakhan rickettsial fever (synonyms: Astrakhan spotted fever, Astrakhan fever, Astrakhan tick spotted fever) is a rickettsiosis from a group of spotted fevers transmitted by the tick of Rhipicephalus pumilio and characterized by benign course, the presence of primary affect, fever, maculopapular rash.

ICD-10 code

A77.8. Other spotty fevers.

Epidemiology of Astrakhan rickettsial fever

The main epidemiologically significant factor in the foci of Astrakhan rickettsial fever is the constant and rather extensive affection of dogs by the tick of Rhipicephalus pumilio, the main reservoir and carrier of rickettsia. Not only stray dogs are affected by mites, but also animals kept on a leash, and guard dogs that do not leave yards. Significant damage to R. Pumilio mites is found in wild animals (eg, hedgehogs, hares). From dogs, from the surface of the soil and plants, mites can crawl to humans. The mites are distributed unevenly in the territory of the region depending on the microclimate, landscape, number and nature of the distribution of the feeders: hedgehogs, hares, etc. A few decades ago, R. Pumilio mites were rarely found in agricultural and domestic animals, although the number of affected wild animals and the degree of their rustling in Northern Caspian were high. Under anthropogenic impact (industrial development of the Astrakhan gas condensate field, construction and commissioning of two stages of the gas condensate plant, the low-activity natural foci of a previously unknown rickettsiosis turned into a manifest natural and anthropurgic focus of Astrakhan rickettsial fever.

Ticks retain rickettsia for life and transmit them transovarially. A person becomes infected when the tick is sucked. It is possible to contaminate the contact path by rubbing the hemolymph of the squashed mite, its nymph or larva into the damaged skin, the mucous membranes of the eyes, nose, or aerosol suspension. The natural susceptibility to Astrakhan rickettsial fever is all-aged. Residents of rural areas of Astrakhan Oblast are more likely to suffer: adults of working age and old age (working in kitchen gardens, cottages, agriculture), preschool and primary school children (more contact with domestic animals). Seasonal diseases: April-October with a peak incidence in July-August, which is associated with an increase at this time of the number of mites, mainly its juvenile forms (nymphs, larvae). The incidence of Astrakhan rickettsial fever is also evident in the regions adjacent to the Astrakhan region, in particular in Kazakhstan. Cases of Astrakhan rickettsial fever are noted among those who have vacationed in the Astrakhan region after their departure.

[1], [2], [3], [4], [5], [6]

What causes Astrakhan rickettsial fever?

Astrakhan rickettsial fever is caused by Rickettsia conori, var. Casp., on morphological and tinctorial properties not differing from other representatives of the group of causative agents of spotty fevers. Rickettsia parasitizes in the cytoplasm. As shown by electron microscopy, the length of the rickettsia is 0.8-1 μm, the cell is surrounded by two triple-layer membranes. Cultivated in tissue culture, as well as in the yolk sac of the developing chick embryo and in the affected mesothelial cells of laboratory animals (golden hamsters). A detailed analysis of the molecular-genetic characteristics of rickettsia that cause astrakhan rickettsial fever allows them to differentiate them from other pathogens of rickettsiosis of the CPL group.

The pathogenesis of Astrakhan rickettsial fever

At the site of suction of the tick, the pathogen begins to multiply and the primary affect is formed. Then the rickettsia penetrate the regional lymph nodes, where they also receive a reproduction accompanied by an inflammatory reaction. The next stage is rickettsiaemia and toxinemia, which are the basis of the pathogenesis of Astrakhan rickettsial fever. Morphologically, in primary affect necrotic lesions of the epidermis, neutrophilic microabscesses of the papillary layer of the skin are observed. Develops acute vasculitis of vessels of different diameters with pronounced swelling of the endothelium, in places with fibrinoid necrosis, destruction of the elastic framework, swelling of collagen fibers of the dermis. There are enlarged lumens of vessels, part of the vessels contains thrombi. Vasculitis first has a local character, within the primary affect, and with the development of rickettsiaemia takes a generalized character. The vessels of the microcirculatory bed are mainly affected: capillaries, arterioles and venules. Developed disseminated thrombovascular.

Hemorrhagic elements are caused by perivascular diapedesis hemorrhages. At the beginning of recovery in the epidermis, the proliferation of basal keratocytes begins; hyperpigmentation develops as a result of the breakdown of red blood cells, hemoglobin; infiltration and swelling of the endothelium decrease; smooth muscle cells of the vessel wall proliferate; Fibrinoid swelling of collagen fibers and dermal edema gradually disappear.

Rickettsia is disseminated in various parenchymal organs, which is clinically manifested by an increase in the liver, spleen, changes in the lungs.

Symptoms of Astrakhan rickettsial fever

There are four periods of the disease:

• incubation;
• elementary;
• the height;
• convalescence.

Astrakhan rickettsial fever has an incubation period that ranges from 2 days to 1 month.

The first symptoms of Astrakhan rickettsial fever are a primary affect at the site of suction of the tick. The frequency and duration of individual symptoms in patients with Astrakhan rickettsial fever

Symptom	Number of patients,%	Duration of preservation of symptoms, days
Fever	100	9-18
Weakness	95.8	12
Headache	88.5	10
Dizziness	33 9	7th
Insomnia	37 5	7th
Conjunctivitis	42.7	7th
Sclerite	45.8	7th
Hyperemia of the pharynx	70.8	8
Hemorrhages in the mucous membranes	151	6.5.
Hemorrhagic rash	41.7	Eleven
Rash is spotty-rosely-papular	100	13
Rash with persistent pigmentation	59.9	11.5
Localization of the rash: hands	98.9	12
Legs	100	Eleven
Torso	100	Eleven
Face	39 1	Eleven
Soles	43.2	10
Palms	34.9	Eleven
Enlargement of lymph nodes	15.6	7th

Astrakhan rickettsial fever has an acute onset, the disease begins with the appearance of fever. Half of the patients with fever are preceded by the appearance of primary affect. In most cases, it is localized on the lower extremities, somewhat less often - on the trunk and in isolated cases - on the neck, head, hands, and penis. Primary affect predominantly single, occasionally observe two elements. The formation of primary affect is not accompanied by subjective sensations, but on the day of its appearance it is sometimes noted a slight itch and soreness. Primary affect looks like a pink spot, sometimes on an elevated base, from 5 to 15 mm in diameter. In the central part of the spot appears point erosion, fairly quickly becoming covered with a hemorrhagic crust of dark brown color. Which is rejected on the 8-23 day of the disease, leaving a pinpoint superficial atrophy of the skin. At the base of primary affect, unlike other tick-borne rickettsiosis, there is no infiltration, the skin defect is extremely superficial with no deep necrotic changes in the dermis. Sometimes it is difficult to recognize among other elements of the rash.

Every fifth patient with primary affect is marked by regional lymphadenitis. Lymph nodes do not exceed the size of the bean; they are painless, mobile, not soldered to each other.

The initial (pre-eczematous) period of Astrakhan rickettsial fever lasts 2-6 days. He has the following symptoms of Astrakhan rickettsial fever: an increase in body temperature, by the end of the day reaching 39-40 ° C, the appearance of a feeling of heat, repeated chills, headache, joint and muscle pain. Deterioration of appetite. The headache increases rapidly, in some patients it becomes painful and deprives them of sleep. Sometimes there is dizziness, nausea and vomiting. In elderly people, a fever may be preceded by prodromal events in the form of increasing weakness: weakness, fatigue, depression of mood. A febrile reaction is accompanied by a moderate tachycardia. During this period, the liver is enlarged. The phenomena of scleritis and conjunctivitis are often recorded. Hyperemia of the mucous membrane of the posterior pharyngeal wall, tonsils, arches and soft skin of the soft palate in combination with complaints of perspiration in the throat and nasal congestion are usually regarded as manifestations of acute respiratory disease, and in case of coughing - as bronchitis or pneumonia.

On the 3rd-7th day of fever, there is a rash and the disease passes into a period of height, which is accompanied by an increase in the symptoms of intoxication.

The rash has a widespread nature with localization on the skin of the trunk (mostly anterolateral regions), the upper (mainly on the flexural surfaces) and lower limbs, including the palms and soles. On the face the rash is rare, in cases with more severe intoxication.

Exanthema usually has polymorphic patchy-rose-papular, hemorrhagic character, in more light cases it can be monomorphic. After the disappearance of the rash, pigmentation persists. The rash on the palms and soles has a papular character. Roseous elements are usually abundant, occasionally single: pink or red, with a diameter of 0.5 to 3 mm. With a heavier current, a fusion of roseol is observed because of their abundance. Roseola often transformed into hemorrhagic spots, most often on the lower limbs.

In the majority of patients, muffled cardiac tones and tachycardia corresponding to the severity of the temperature reaction are detected, less frequent abnormalities of the rhythm (paroxysmal tachycardia, extrasystole, ciliary arrhythmia), and occasionally arterial hypotension.

The tongue is coated with a grayish coating. Appetite is reduced right up to anorexia. The phenomena of cheilitis are observed. In the early days of the disease, transient diarrhea is possible. Each second patient is followed by hepatomegaly, on average, on the 10th to 12th day of the disease. The liver is painless, of a dense elastic consistency, the lower edge of it is even, the surface is smooth. Increase spleen almost never occurs.

Body temperature above 39 ° C persists for 6-7 days, fever above 40 ° C is rarely observed. On average, up to the 7th day, many patients are concerned about chills. The temperature curve is remittent, more rarely - constant or of an incorrect type. The febrile period lasts an average of 11-12 days, ending in most cases with a shorter lysis.

With the normalization of the temperature, the period of convalescence begins. Patient health gradually improves, symptoms of intoxication disappear, appetite appears. Some recovering phenomena of asthenia remain relatively long.

Astrakhan rickettsial fever can be complicated by pneumonia, bronchitis, glomerulonephritis, phlebitis, metro- and rhinorrhagia, infectious-toxic shock, acute impairment of cerebral circulation. In some patients, signs of toxic CNS damage (nausea or vomiting with severe headache, vivid erythema of the face, stiff neck and Kernig's symptom) are noted. In the study of cerebrospinal fluid, changes in the inflammatory character are not detected.

The picture of blood is usually very small. There is normocytosis; significant changes in the formula and indices of phagocytic activity are absent. In severe cases, leukocytosis, thrombocytopenia, signs of hypocoagulation are observed. A urine test in many cases reveals proteinuria, an increase in the number of leukocytes.

Diagnosis of Astrakhan rickettsial fever

Diagnostic criteria of Astrakhan rickettsial fever:

• epidemiological data:
  • Seasonality of the disease (April-October),
  • stay in a natural (anthropurgic) outbreak,
  • contact with ticks (imago, larvae, nymphs);
• high fever;
• marked intoxication without development of typhoid status;
• arthralgia and myalgia;
• plentiful polymorphous nevlivayuschayasya and nezudyashchaya rash on the 2-4th day of the disease;
• primary affect:
• scleritis, conjunctivitis, catarrhal changes in the throat;
• enlargement of the liver.

The specific diagnosis of Astrakhan rickettsial fever uses the reaction of the RNIF with the specific antigen of the pathogen. Investigate paired blood sera, taken at the height of the disease and in the period of convalescence. The diagnosis is confirmed with a 4-fold and more increase in antibody titers. The PCR method is also used.

[7]

Differential diagnosis of Astrakhan rickettsial fever

At a prehospital examination, diagnostic errors were admitted in 28% of patients with Astrakhan rickettsial fever. Astrakhan rickettsial fever should be differentiated from typhus. Measles, rubella, pseudotuberculosis, meningococcemia. Crimean hemorrhagic fever (CGL), leptospirosis, enterovirus infection (enterovirus exanthema), secondary syphilis.

Differential diagnosis of Astrakhan rickettsial fever

Nosoform	Symptoms common to ARL	Differential-diagnostic differences
Typhus	Acute onset, fever, intoxication. Defeat of the central nervous system. Rash of enanthem, enlargement of the liver	Fever longer, up to 3 weeks, CNS involvement more severe, with frustration of excitement, persistent insomnia, tabloid disorders, tremor: the rash appears on the 4-6th day of the disease does not rise above the surface of the skin, rose-petechial. The face is hyperemic. Sclera and conjunctiva are injected. Spots of Chiari-Avtsyn: the spleen is enlarged. Primary affect is absent, lymphadenopathy. Seasonality is winter-spring, caused by the development of pediculosis. Positive RNIF and RSK with Provacek antigen
Measles	An acute beginning, a fever. Intoxication, rash	Expressed catarrhal phenomena, rash on the 4-5th day, poured out in stages, rough, draining, spots Belsky-Filatov-Koplik. On the palms and feet, there is no rash. There is no connection with suction (contact) of the mite, as well as primary kt
Rubella	Fever, rash, lymphadenopathy	Fever short-term (1-3 days), the rash is absent on the palms and feet, intoxication is not expressed. The predominantly posterior-cervical lymph nodes are enlarged, there is no connection of the disease with suction (contact) of the mite, as well as primary affect. In the blood - leukopenia and lymphocytosis
Pseudotuberculosis	An acute beginning, a fever. Intoxication, rash	The rash is rough, more abundant in the region of the joints; symptoms of "socks", "gloves", dyspeptic syndrome. Neurotoxicosis, arthralgia, polyarthritis are not characteristic, there is no connection of the disease with suction (contact) of the mite, as well as primary affect
Meningococcemia	Acute onset, fever, intoxication, rash	The rash that appears in the first day, hemorrhagic, mainly on the limbs, is rarely abundant. From the 2nd day in most patients - purulent meningitis. The enlargement of the liver is not typical. Primary affect and lymphadenopathy are not observed. In the blood - neutrophilic leukocytosis with a shift of the formula to the left. Links with suction (contact) of the tick are not observed
KGL	Acute onset, fever, intoxication, facial hyperemia rash, CNS damage, primary affect, tick sucking	Rash hemorrhagic, other manifestations of hemorrhagic syndrome, pain in the abdomen, dry mouth. Severe leukopenia, thrombocytopenia, proteinuria, hematuria. Patients are contagious
Leptospirosis	An acute onset, chills. High fever, rash	The fever level is higher, the rash is ephemeral, not pigmented. Jaundice. Hepatolyenal syndrome. Myalgia is pronounced. Defeat of the kidneys up to the arrester. Often - meningitis. In the blood - neutrophilic leukocytosis, in the urine - protein, leukocytes. Erythrocytes, cylinders. There is no relationship of disease with suction (contact) of the mite, as well as primary affect. Lymphadenopathy is absent
Enterovirus exanthema	Acute onset, fever, intoxication, maculopapular rash. Enanthema	Catarrhal phenomena are expressed. Rashes on the palms and soles are rare, characterized by conjunctivitis. An increase in the cervical lymph nodes. Often, serous meningitis. There is no relationship of disease with suction (contact) of the mite, as well as primary affect
Secondary syphilis	Rose-lupus-papular rash, lymphadenopathy	Fever and intoxication are not characteristic, rashes stable, persist 1.5-2 months. Including on the mucous membranes. There is no relationship of disease with suction (contact) of the mite, as well as primary affect. Positive serological syphilitic assays (RW, etc.)

[8], [9]

Indications for hospitalization

Indications for hospitalization:

• high fever;
• marked intoxication;
• tick sucking.

Treatment of Astrakhan rickettsial fever

Etiotropic treatment of Astrakhan rickettsial fever is carried out with tetracycline inwards at a dose of 0.3-0.5 g four times daily or with doxycycline on the first day of 0.1 g twice daily, in the following days 0.1 g once. Rifampicin is also effective at 0.15 g twice daily; erythromycin, 0.5 g four times a day. Therapy with antibiotics is carried out until the 2nd day of normal body temperature inclusive.

When expressed hemorrhagic syndrome (profuse hemorrhagic rash, bleeding gums, nosebleeds) and thrombocytopenia prescribe ascorbic acid + rutoside, calcium gluconate, menadione sodium, bisulphite, ascorbic acid, calcium chloride, gelatin, aminocaproic acid.

How is Astrakhan rickettsial fever prevented?

Specific prophylaxis of Astrakhan rickettsial fever is not developed.

The disinfestation of dogs, the catching of stray dogs are important.

In epidemic outbreaks during a stay in nature during the season of Astrakhan rickettsial fever it is necessary to conduct self-and mutual examinations in order to detect ticks in time. It should be dressed so that the outer clothing, if possible, was solid. Which facilitates the search for insects. Trousers recommend to dress in knee-length socks. Shirt - in trousers: sleeves cuffs should fit snugly to the hands. You can not sit and lie on the ground without special protective clothing, spend the night in nature, if safety is not guaranteed.

To protect against mites, insecticides are recommended, for example permethrin.

To reduce the risk of ticks crawling from livestock and other animals per person, it is necessary to systematically inspect animals in spring and summer, remove the sucking mites with rubber gloves and avoid crushing them. Mites collected from animals should be burned.

Adherent to the human tick must be removed with tweezers together with the head; Place the bite with a disinfectant solution; To send the mite to the Gossanepidnadzor center for establishing its infectiousness.

What prognosis does Astrakhan rickettsial fever have?

Astrakhan rickettsial fever has a favorable prognosis.

Patients are discharged 8-12 days after normalization of body temperature