Brucellosis is a zoonotic infection characterized by multiple organ pathologies and a tendency to chronization. An important pathogenetic component of brucellosis is allergic reactivity. Brucella transmission occurs mainly by food and water, most often through milk and meat of infected animals. In cattle breeders, an aerial and contact pathway of brucellosis transmission can be realized. The diagnosis is established when the pathogen is detected in the blood, punctate of the lymph node or cerebrospinal fluid. Serological diagnostics can be considered reliable with a positive result of several different methods at once: ELISA, RIF, etc.
General information
Brucellosis is a zoonotic infection characterized by multiple organ pathologies and a tendency to chronization. An important pathogenetic component of brucellosis is allergic reactivity. Brucellosis is classified according to the nature of the course, distinguishing acute (duration up to one and a half months), subacute (no more than four months), chronic (more than four months) and residual (long-term consequences) forms.
Causes
Brucellosis is caused by immobile polymorphic gram-negative microorganisms of the genus Brucella. The type of brucella that causes infection affects the severity of the course, the most severe is brucellosis caused by infection with Brucella melitensis. Brucella are highly invasive, multiply inside the cells of the host organism, but are able to remain active outside the cell. They are stable in the environment, they remain in water for more than two months, three months – in raw meat (30 days – in salted), about two months – in cheese and up to four months – in animal hair. Boiling is disastrous for brucella, heating to 60 ° C kills them after 30 minutes.
The reservoir of brucellosis is animals, the source of infection for humans are mainly goats, sheep, cows and pigs. In some cases, transmission from horses, camels, and some other animals is possible. The release of the pathogen by sick animals occurs with feces (feces, urine), milk, amniotic fluid. Transmission of infection is carried out mainly by the fecal-oral mechanism, most often by food and water, in some cases it is possible to implement a contact-household (with the introduction of the pathogen through microtrauma of the skin and mucous membranes) and aerogenic (with inhalation of infected dust) pathways.
Milk obtained from sick animals and dairy products (cheese, koumiss, cheeses), meat, products from animal raw materials (wool, leather) are a significant epidemiological danger. Animals pollute the soil, water, and feed with their feces, which can also contribute to human infection by non-food means. Contact-household and air-dust routes are implemented in the care of animals and the processing of animal raw materials.
With brucellosis in pregnant women, there is a possibility of intrauterine transmission of infection, in addition, postnatal transmission during lactation is possible. People have a high susceptibility to brucellosis, after suffering an infection for 6-9 months, immunity remains. Repeated infection with brucella is noted in 2-7% of cases.
Brucellosis symptoms
The incubation period of brucellosis is on average 1-4 weeks, but when a latent carrier is formed, it lengthens to 2-3 months. Acute brucellosis usually develops quickly, in the elderly, the onset may be gradual (in this case, patients note prodromal phenomena in the form of general malaise, insomnia, weakness, arthralgia and myalgia with a gradual increase in intoxication for several days). The body temperature rises sharply to high figures, terrific chills alternate with torrential sweat, intoxication develops, most often moderate, despite a pronounced temperature reaction.
The febrile period is most often several days, sometimes lasting up to 3 weeks or a month. Patients note sleep disorders, appetite, headaches, emotional lability. At the peak of the temperature curve, hyperemia and swelling of the face and neck are noted against the background of general paleness. Moderate polylymphoadenopathy is detected – lymph nodes, mainly cervical and axillary, are slightly enlarged in size and moderately painful to the touch. In the acute form, fibrositis and cellulitis, more characteristic of the subacute course of brucellosis, may also occur – dense painful formations along the tendons and muscles the size of a pea (sometimes they reach the size of a small chicken egg).
Subacute brucellosis
The subacute form of brucellosis is characterized by alternating relapses of fever with periods of normal temperature. Feverish periods can be of varying duration, the temperature increase ranges from subfebrility to extremely high values (including during the day). Fever has a directional character. An increase in temperature is accompanied by intoxication signs: pain in the muscles and joints, paresthesia (tingling sensations, “goosebumps” in various parts of the body), general weakness, decreased appetite and cardiac arrhythmia (at fever altitude, there is a relative bradycardia – a discrepancy in the rhythm frequency to body temperature). At normal temperature, there may be an increase in the pulse rate. The heart tones are muted. Patients are thirsty, complain of dry mouth, constipation is not uncommon.
This form of the disease is often accompanied by fibrosis and cellulite. In severe cases, it is possible to develop an infectious and toxic shock, complications in the form of inflammation of the membranes of the heart (pericarditis). The subacute form of brucellosis is accompanied by manifestations of allergies – rashes, dermatitis, vascular reactions, etc.). The first thing usually affects the articular apparatus: reactive polyarthritis, bursitis and tendovaginitis develop. Men are characterized by the defeat of the testicles and their appendages, women may have menstrual disorders, endometritis. Brucellosis during pregnancy can contribute to its premature birth.
Chronic brucellosis
It proceeds in waves, with the manifestation of symptoms of multiple organ lesions. At the same time, the general intoxication syndrome (fever and intoxication) is usually expressed moderately, the temperature rarely exceeds subfebrile values. The intervals between exacerbations of the disease can last 1-2 months. In the case of the formation of a new infectious focus inside the body, the general condition worsens. The symptoms of chronic brucellosis depend on the predominant lesion of a particular functional system by the pathogen and the severity of the allergic component.
Inflammation of the joints (arthritis) and surrounding tissues, connective tissue pathologies (fibrosis, cellulite) in the lumbar and sacrum, elbow joints often develop. Sometimes spondylitis develops, which significantly worsens the condition of patients due to intense pain and restrictions in movement. Joints are often subject to destruction and deformation.
Neuritis (including inflammation of the optic and auditory nerves) and radiculitis, inflammation of the nerve plexuses, paresthesia are not uncommon in patients with brucellosis. The long course of the disease contributes to the development of reactive neurosis. Chronic brucellosis is also characterized by allergic inflammation of the genital glands and fertility disorders (infertility in women, impotence in men). The duration of the disease can be 2-3 years and increase with repeated infection.
Residual brucellosis
Residual brucellosis – delayed consequences of infection – is associated with the formation of pathological reactivity. Due to the restructuring of the immunological structure of the body, specific reactions of the body are possible – subfebrile body temperature, psychological deviations, pathology of joints, connective tissue formations.
In addition, brucellosis can leave behind serious degenerative changes in fibrous tissue, especially significant in the area of nerve trunks and plexuses – there is a high probability of contractures, neurological symptoms (paresis, neuropathy). The long course of the disease contributes to the formation of persistent functional disorders on the part of musculoskeletal structures due to the irreversible destruction of articular tissues and ligamentous apparatus (ankylosis and spondylosis, contractures, muscular atrophy). Often such consequences of brucellosis are an indication for surgical correction.
Diagnostics
Bacteriological diagnostics is performed in specialized laboratories equipped to work with pathogens of particularly dangerous infections. Brucella is isolated from blood, cerebrospinal fluid, lymph node punctates, producing back-sowing of biological material on nutrient media. Due to the considerable labor costs, the pathogen is rarely isolated for diagnostic purposes, the determination of antigens to brucella in the patient’s blood and serological tests is sufficient to confirm the diagnosis.
Antigens are detected using ELISA, RCA, RLA and RAGA. Blood serum is usually examined, but it is possible to detect antigens in the cerebrospinal fluid. The determination of antibodies is carried out using RA, RNGA, RSC, RIF, as well as the Wright reaction and the test for the interaction of brucella with the patient’s serum. A positive result in at least 3-4 different serological tests is considered sufficient for diagnosis. Starting from the 20th-25th day of the disease and for a long period (several years) after recovery, a positive reaction to the skin test of Burne (subcutaneous administration of brucellin) is noted.
Brucellosis treatment
Outpatient treatment is indicated for mild infection. In case of severe course and threat of complications, hospitalization is performed. For the period of fever, patients are shown bed rest. Etiotropic therapy involves the appointment of antibiotics of various groups, one of the drugs must necessarily have the ability to penetrate the cell wall. The use of the following antibiotic pairs is effective: rifampicin with doxycycline or ofloxacin, doxycycline with streptomycin. In case of relapse, a second course of antibiotic therapy is prescribed.
In addition to basic therapy, pathogenetic and symptomatic agents are prescribed: detoxification therapy (depending on the severity of intoxication), immunostimulating agents (cattle thymus extract, pentoxil), novocaine blockades for spondylitis and intense sciatica, anti-inflammatory drugs (nonsteroidal drugs and corticosteroids, depending on the course and joint manifestations).
Previously, a therapeutic vaccine was used in the complex therapy of brucellosis, but currently this practice is being abandoned due to the pronounced suppression of immunity and the ability of the vaccine to provoke autoimmune processes. During remissions, patients are recommended spa treatment, physiotherapy (UHF, quartz, radon baths, etc.) and physical therapy.
Prognosis and prevention
Usually brucellosis does not cause the death of patients, the prognosis is usually favorable. In cases of prolonged course and development of persistent destructive defects of the articular apparatus, disability may be limited.
The complex of preventive measures aimed at reducing the incidence of brucellosis in humans includes veterinary control over the health of farm animals, as well as sanitary and hygienic rationing of production conditions, storage and transportation of food products, annual preventive examinations of agricultural workers.
Agricultural cattle are subject to routine vaccination, and specific prophylaxis with live brucellosis vaccine is also indicated to persons working directly with animals. The means of individual prevention also include overalls for working with animal raw materials, strict adherence to the rules of personal hygiene.