Boutonneuse fever is an acute infectious disease caused by intracellular bacteria rickettsii. The diagnostic triad includes the presence of primary affect, regional lymphadenitis, skin rash. There is also fever, weakness, myalgia, moderate headache, arthralgia, facial hyperemia, less often hepatosplenomegaly. Diagnosis is based on the detection of antibodies to the pathogen and rickettsia itself in the skin biopsy, blood. Treatment includes etiotropic (antibacterial) therapy and symptomatic agents: detoxification, antipyretic, angioprotectors.
ICD 10
A77.1 Spotted fever caused by Rickettsia conorii
General information
Boutonneuse fever (pimple fever, canine disease, infectious exanthema of the Mediterranean Sea) is a disease with a transmissible transmission pathway. The infection was first described by French doctors Conor and Bruch in 1910 in Tunisia. In the 20s of the twentieth century, it was studied in Marseille by French scientists Olmer, which was reflected in the name of nosology. It is widespread in the countries of the Mediterranean, Caspian, and Black Seas. There are no gender and age characteristics. It is usually diagnosed from May to October, in the south it can be detected year-round. Risk groups are dog breeders, children, veterinarians, residents of rural areas.
Causes
The causative agent of the infection is the bacterium Rickettsia (Rickettsiaconori). The source of infection are dogs, hedgehogs, jackals, rodents and some other mammals. Carriers of infection are ticks, most often canine, among which there is a long-term persistence of contagion (more than a year) and transovarial transmission of rickettsias. The seasonal increase in the number of cases of the disease is associated with the breeding and activity of vectors, while both young individuals and overwintered adult ticks play an important role. Females lay millions of eggs, very often near animal habitats, especially domestic ones (dog kennels).
Canine or European forest ticks live in Asia, Europe and North Africa. The way of transmission to a person is through suction, when rubbing the tick with bare hands, crushing the carrier near the mucous membranes of the mouth, nose, eyes. Risk factors for the development of severe forms of the disease, accounting for up to 6% of the total number of cases, are diabetes mellitus, chronic alcoholism, glucose-6-phosphate dehydrogenase deficiency, cardiovascular pathology, terminal renal failure.
Pathogenesis
The suction of the carrier ensures that the pathogen enters the thickness of the patient’s dermis. At the site of introduction, the primary affect develops: inflammation, edema, ulcerative skin lesions. Then infectious agents penetrate into the lymphatic vessels, regional nodes with the development of inflammatory changes. From the lymphatic system, rickettsias enter the systemic circulation. Bacteria live intracellularly, have a tropicity to the endothelium, in the cells of which they multiply, which provokes thromboendovasculitis of small vessels and the formation of specific granulomas.
Disseminated vascular damage leads to the formation of lymphohistiocytic infiltrates in the central nervous system, lungs, kidneys, thyroid gland, adrenal cortex and a decrease in the functions of these organs, which exacerbates coagulopathy and stimulates thrombosis. Toxins secreted by bacteria contribute to the occurrence of intoxication, allergic reactions, general sensitization of the body, a transient decrease in the level of CD4+ lymphocytes. The causative agents of boutonneuse fever cause a significant increase in the number of molecules of monocytic chemoattractant protein, Willebrand factor, fibrin degradation products, interleukin-8, induce activation of toll-like endothelial adhesion receptors.
Boutonneuse fever symptoms
The incubation period is 3-18 days (usually a week). At the site of the tick suction, a primary affect occurs – a painless dense infiltrate with hyperemia of the skin up to 10 mm in diameter, in the center of which there is a necrosis lesion up to 3 mm in size, covered with a black crust (tash-noir, Etash). Sometimes patients notice a slight itching in the area of affect. The ulcer located under the crust heals on its own by the recovery period, often leaving a hyperpigmentation area after the disappearance. A third of patients report an increase, densification, sensitivity of regional lymph nodes. In some cases, the primary affect can be detected only by local lymphadenitis, very rarely there is no “black spot”.
The disease begins suddenly against the background of full health with an increase in body temperature to 38.5 ° C and above, chills, moderate headache, insomnia, pronounced weakness, muscle and joint pain, less often vomiting. Constipation and decreased diuresis may occur. The face becomes puffy, reddened, the mucous membranes of the throat and eyes are hyperemic. On 2-4 days of the disease, a spotty papular, vesicular rash appears on the chest and abdomen, which spreads to the limbs, palms, soles, neck, face. Rashes leave behind pigmentation lasting up to 3 months. Alarming symptoms are considered to be abundant hemorrhages on the skin and mucous membranes, bleeding, hemoptysis, a sharp decrease in diuresis.
Complications
Untimely access to a doctor, old age and burdened premorbid background – coronary heart disease, lymphogranulomatosis, other chronic somatic pathologies, obesity, tobacco and alcohol abuse – contribute to the development of complications. The most frequent negative consequences are thrombophlebitis, laryngotracheitis, bronchitis, pneumonia, pleuropneumonia, thromboembolism. Less common are meningoencephalitis, delirium, typhoid status, strokes, syncopal conditions, anasarca, Guillain-Barre syndrome, hearing loss due to damage to the auditory nerve, rhabdomyolysis, acute renal failure, endocarditis, pericarditis, arrhythmia, atrial fibrillation.
Diagnostics
Consultations of an infectious disease specialist, a dermatovenerologist are considered mandatory. It is necessary to clarify the fact of tick sucking, the presence of pets (dogs), staying in forest-steppe zones, Mediterranean countries, parks, on tourist routes. Objective, laboratory and instrumental criteria of boutonneuse fever are:
- External inspection. Physical examination reveals an infiltrate with a black crust or ulcer in the center, enlargement, tenderness of regional lymph nodes, hyperemia of the face, pharynx, injection of conjunctival vessels, maculopapular, vesicular, rarely hemorrhagic rash on the body, brighter on the lower extremities, a tendency to bradycardia and arterial hypotension, hepatosplenomegaly.
- Laboratory tests. In the blood test, leukopenia, lymphocytosis, thrombocytopenia, acceleration of ESR are observed, less often anemia. A biochemical blood test reveals an increase in the activity of ALT, CPK, LDH, AST, hyponatremia. A promising method for predicting the severity and outcome of the disease is to determine the level of soluble fractions of selectins as markers of endothelial damage. In the general clinical analysis of urine, minor albuminuria, microhematuria is detected.
- Identification of infectious agents. PCR research can be used from the first days of the disease, it is carried out with blood, biopsies taken from the primary affect or a skin area with a rash. Serological methods are used for retrospective diagnosis, the most informative is ELISA – a significant increase in antibody titer occurs from 5-10 days of the disease and becomes diagnostically significant by 45 days.
- Radiation methods. Chest radiography is necessary for differentiation with other diseases, verification of secondary pneumonia. Ultrasound of lymph nodes confirms the increase in size, hypoechoicity, uniformity of structure. Ultrasound of the abdominal cavity in 50% of cases determines hepatomegaly, in 30% – enlargement of the spleen. The ECG may be within the normal range, but bradycardia is more often detected.
Differential diagnosis is carried out with meningococcal infection, chickenpox, anthrax, tularemia, measles, cat scratch disease, abdominal, rat, typhus, Rocky Mountain spotted fever, rubella, HFRS, hemorrhagic fevers, trichinosis, North Asian tick-borne rickettsiosis, paratyphosis A, B, sepsis, ixodes tick-borne borreliosis, syphilis, thrombocytopenic purple, Wiskott-Aldrich syndrome, allergic reactions.
Treatment
Patients suspected of this infection are non-contagious, but should be hospitalized for epidemiological and clinical indications. Bed rest is introduced until a steady decrease in body temperature for 5-6 days. The diet includes easily digestible nutritious meals at room temperature, excludes alcohol, seasonings, fried food. In the absence of food allergies, it is recommended to introduce foods rich in vitamin C (kiwi, citrus fruits) into the diet.
Etiotropic drugs used in the treatment of boutonneuse fever are antibiotics (tetracycline, doxycycline, azithromycin, clarithromycin). Detoxification agents (acesol, succinate-containing, glucose-salt solutions), angioprotectors (rutoside), antipyretics (celecoxib) are also used. It is necessary to exclude aspirin-containing medications. To reduce the severity of hemorrhagic syndrome, calcium preparations, aminocaproic acid, tranexamic acid are prescribed.
Prognosis and prevention
Timely referral to a medical institution and the course of pathology in mild or moderate form allow predicting a favorable outcome. The death of patients is registered in 2-6% of cases, usually among elderly patients with secondary bacterial pneumonia and decompensation of chronic diseases. Specific prevention (vaccine) has not yet been developed. Non-specific measures include recommendations on preventing contact with stray animals, trapping stray dogs, using sprays, protective clothing, tick repellents, treating places of mass stay of people with insecticides at the beginning of the season.