Meningitis in children - I.V. Bohadelnikov 2005

Aseptic meningitis in children. General data
Ornithosis meningitis

Ornithosis meningitis is an acute infectious disease belonging to the group of zoonoses, caused by chlamydiae and clinically characterized by prolonged fever, meningeal syndrome, often combined with damage to the Lungs and other Organs and systems.

Etiology. The causative agents, Chlamydia ornithosis psittaci, belong to a genus that occupies an intermediate position between Viruses, Bacteria, and rickettsiae. They are Obligate Intracellular Parasites, incapable of growing on Cell-free nutrient media. The size of the microorganism at various Selection/3.html">Stages of development ranges from 400 to 1200 nm. The average duration of the developmental cycle is 40-48 hours. Chlamydiae can be cultured in chicken embryos, tissue cultures, and passaged in white mice. They are inactivated by heating above 70°C and by disinfectants (lysol, formalin, chloramine, ether). In the external environment, chlamydiae persist for up to 2-3 weeks. They are resistant to sulfonamides, streptomycin, kanamycin, nystatin, and Other Antibiotics. They are sensitive to Tetracyclines and macrolides.

Epidemiology. Domestic and wild birds serve as the reservoir and source of ornithosis infection. Currently, the CAUSATIVE AGENT OF ornithosis has been isolated from more than 140 bird species. Epizootics can occur among birds. Poultry (especially ducks and turkeys), pet birds (parrots, small songbirds), and particularly urban pigeons, whose infection rate reaches 30-80%, are of the greatest epidemiological significance, with the infection in them usually running a latent course. The pathogen is shed by birds in feces and respiratory secretions. The disease is widespread worldwide. Ornithosis is often unrecognized and misdiagnosed as Pneumonia. Patients with ornithosis do not pose a danger to others. Transmission occurs mainly via the aerogenic route; however, alimentary transmission (through the consumption of infected duck or turkey meat) is noted in 10% of patients.

Infection in children most often occurs through contact with birds. Usually, sporadic cases are recorded among children, but epidemic outbreaks are also possible in organized children's groups if sick ornamental birds are kept indoors.

Pathogenesis. The portal of entry for aerogenic infection is the respiratory mucosa. Penetration most commonly occurs in the small Bronchi and bronchioles. The developmental cycle and accumulation of the pathogen begin first in epithelial Cells and then in the interstitial tissue. Being an obligate intracellular microorganism, the pathogen destroys cells. Released chlamydiae, toxins, and cellular debris enter the bloodstream, causing general intoxication, systemic sensitization, and lung damage. In severe cases, hematogenous dissemination of the pathogen to parenchymal organs, the CNS, myocardium, etc., is possible.

Much less frequently, the mucosa of the alimentary tract can serve as the portal of entry. Penetration of the pathogen occurs in the lower PARTS OF THE Small Intestine. In this case, Circulation of the pathogen in the Blood is also observed, accompanied by pronounced general intoxication and often significant enlargement of The Liver and Spleen, though secondary hematogenous pneumonia does not develop. If the BBB is breached, meningitis develops, which in children can occur even without the involvement of other organs and systems.

In individuals with a strong immune system, the infection is asymptomatic. Clearance of the pathogen from the body in most patients occurs within a few weeks, but sometimes chlamydiae persist in the body for several years, which accounts for the possibility of disease relapses. In the pathogenesis of ornithosis, the secondary bacterial flora plays an important role, so the process often runs as a mixed chlamydial-bacterial infection.

Pathomorphology. In CNS involvement, the arachnoid and pia mater are congested and edematous. Their diffuse infiltration is noted, which is most pronounced perivascularly and consists of lymphocytic and plasma cells. Similar changes are observed in the choroid plexuses of the ventricles, and much less frequently in the Brain parenchyma. Stasis with plasmorrhagia and isolated petechial hemorrhages are observed on the Meninges and in the subependymal region of the brain ventricles. The ventricles are dilated, and they, as well as the subarachnoid space, contain an excessive amount of CEREBROSPINAL FLUID mixed with serous inflammatory exudate, containing mainly lymphocytic cells. These changes usually undergo complete resolution. The formation of a cicatricial-adhesive process with persistent Hydrocephalus after meningitis is rare.

Clinical presentation. The incubation period ranges from 6 to 17 days. In the atypical form of ornithosis, meningitis is uncommon, accounting for only 1-2% of all cases of acute ornithosis. It begins acutely with the onset of symptoms of intoxication. Within the next 2-4 days (less frequently after 6-8 days), meningeal symptoms develop (nuchal rigidity, Kernig's and Brudzinski's signs, and in infants in the first months of life, bulging and pulsation of the anterior fontanelle, Lesage's and Flatau's signs). Intracranial Hypertension is clearly pronounced: There is a sharp headache and vomiting. No Changes in the lungs are observed in this form of ornithosis. On lumbar puncture, CSF flows under pressure and is clear; moderate pleocytosis from 20 to 500 cells per 1 μl with a predominance of lymphocytes is noted; protein content is moderately increased with normal glucose and chloride levels. The disease has a prolonged course. Fever often has an undulating course and persists for 3-4 weeks. CSF clearance occurs 5-6 weeks after the onset of the disease or later. No persistent residual neurological signs are observed after ornithosis meningitis.

In the typical form of ornithosis, meningitis develops following pneumonia. The onset of pneumonia is acute, with a rise in body Temperature to 39°-40°C, headache, and Muscle pain. Dry cough, sore throat, scleral and conjunctival injection, and facial flushing are characteristic. A maculopapular or roseolous allergic rash sometimes appears on the trunk. Lung changes progressively increase. Initially, signs of tracheobronchitis are detected, and starting from the 3rd, 5th, or 7th day of illness, focal, segmental, or confluent pneumonia forms in the lungs, predominantly in the lower lobes. In the absence of bacterial complications, lung changes often run an atypical course, without pronounced physical findings, and are not accompanied by dyspnea. Ornithosis in infants and young children is very severe, usually presenting as pneumomeningoencephalitis or meningoencephalomyocarditis. They are more likely than adults to experience stool disorders and involvement of the liver and spleen.

The main diagnostic criteria for ornithosis meningitis:

Epidemiological history: contact with infected domestic or wild birds, less commonly consumption of infected poultry meat, predominantly sporadic incidence, and absence of seasonality.

In the atypical form of ornithosis, meningitis begins acutely; in the typical form, it always follows pneumonia.

Meningitis is often combined with the involvement of other organs, such as the lungs, Heart, liver, and spleen.

CSF clearance occurs late, 5-6 weeks or more after the onset of the disease.

Laboratory Diagnostics. Complete blood count. Peripheral blood shows normocytosis or leukopenia; the differential WHITE BLOOD CELL count is characterized by lymphocytosis, monocytosis, and aneosinophilia; the ESR is moderately elevated.

Bacteriological examination. Isolation of chlamydiae from blood, CSF, oropharyngeal swabs, and sputum is possible. White mice, chicken embryos, or cell cultures (L 929, HLA, etc.) are inoculated with the material, followed by identification of the isolated pathogen. Methods of chlamydia isolation are labor-intensive and therefore not used in routine clinical practice.

Serological testing. To detect specific Antibodies, CFT and IHA are used.

a) CFT with a group-specific ornithosis antigen is a traditional and widespread diagnostic method. Complement-fixing antibodies appear no earlier than the 4th-6th day of illness, and sometimes not until the 3rd week (with early initiation of antibacterial therapy). Peak antibody titers are recorded at the 4th-5th week, followed by their rapid decline. Paired sera are tested at an interval of 8-14 days; titers of 1:64 and higher have diagnostic value. The value of the test is reduced by the possibility of false-positive results due to antigen cross-reactivity.

b) HI is a more specific and sensitive test that does not yield false-positive results. The diagnostic titer in the acute period is 1:152, followed by at least a twofold increase.

c) ELISA is considered more promising, as it allows the detection of specific anti-ornithosis antibodies of different classes - Ig, Ig, Ig. The presence of Ig and Ig antibodies characterizes an active infection, while Ig Class antibodies are anamnestic.

CSF examination. The fluid is clear; neutrophils are detected in the first days, but within a few days, lymphocytes predominate and account for 80-90%.

Allergy testing. The earliest method for diagnosing ornithosis is the intradermal test with ornithosis allergen. The antigen is administered intradermally at a dose of 0.1 ml into the inner surface of the forearm. In the presence of the disease, erythema and induration occur at the injection site. The reaction is positive as early as the 2nd-3rd day of illness and remains positive for several months or even years after recovery, which is used for retrospective Diagnosis and epidemiological surveys.

Detection of specific antibodies simultaneously with a positive intradermal test with ornithosis allergen is convincing Evidence of the ornithosis nature of meningitis.