Legionellosis in children (Legionnaires' disease, Pontiac's fever): causes, symptoms, diagnosis, treatment

Legionellosis (Legionnaires' disease, Pontiac fever) is an acute infectious disease of bacterial etiology with fever, respiratory syndrome, lung damage, often GIT, central nervous system and kidneys.

ICD-10 code

• A48.1 Legionnaires' disease.
• A48.2 Legionnaires' disease without pneumonia (Pontiac fever).

Epidemiology of legionellosis

Legionelles live in warm open reservoirs, overgrown with algae. In addition, they are preserved and multiplied for a long time in water supply and air conditioning systems, tower towers, shower units, baths for balneotherapy procedures, medical equipment for inhalations and artificial ventilation of the lungs.

The transmission of infection is always carried out by an aerogenic dusty airway. Intermediaries of transmission of the causative agent are both air and water - condensate in air conditioners. Other transmitters can be the heads of shower installations, dust raised during excavation, soil in endemic foci. The transmission of infection from person to person is unlikely. Infection of children can occur in preschool institutions, schools, children's homes and other premises with defective air conditioners. Nosocomial outbreaks of legionellosis are described. Which gives grounds for considering this disease as a nosocomial infection.

The incidence is recorded in the form of epidemic outbreaks or sporadic cases, mainly in the summer-autumn period. Persons of all ages are sick, including infants.

Classification

There are pneumonic form, catarrh of the upper respiratory tract, acute feverish diseases with exanthema.

Causes of legionellosis

Pathogen - Legionella, from the family Legionellaceae - gram - negative rod, numbering more than 35 species: L. Pneumophila, L. Bozemanii, L. Micdadei, etc. The species of L. Pneumophila is the most numerous, its representatives are divided into 15 serogroups and each of them can cause disease in humans. To cultivate the pathogen, artificial nutrient media are used with the addition of L-lecithin and iron pyrophosphate (Mueller-Hinten medium), as well as chicken embryos.

Pathogenesis of Legionellosis

The site of the primary localization of the infection is the mucous membrane of the upper respiratory tract (with respiratory legionellosis) or lung tissue (with pneumonic form), where the accumulation of the pathogen occurs with the development of the inflammatory process. Further development of the disease depends on the dose and pathogenicity of the causative agent, preceding sensitization, and most importantly - on local and general resistance of the organism.

Symptoms of Legionella

Incubation period of legionellosis from 2 to 10 days.

The pneumonic form of legionellosis begins acutely with rising body temperature, cognition, muscle aches and headaches. From the first days there are dry cough, runny nose, pain behind the sternum during a cough. These symptoms progress for 3-5 days, body temperature reaches a maximum (39-40 ° C), symptoms of intoxication are expressed, cough becomes wet with sputum discharge, dyspnea increases. When percussion in the lungs, foci of shortening of percussion sound are detected, and in case of auscultation crepitating and finely bubbling wet wheezes are heard in the projection of these foci against the background of weakened breathing. On the roentgenogram, focal shadows are identified with a tendency to merge and form large obscuration zones. In rare cases, pleurisy or mild exudation to the pleural cavity is possible.

In peripheral blood leukocytosis, neutrophil shift, the tendency to thrombocytopenia and lymphopenia, a sharp increase in ESR.

Qatar of the upper respiratory tract of legionellae etiology is practically indistinguishable from ARI of viral nature: body temperature is raised to 38-39 ° C, cough, runny nose, and cognition are noted. There are muscular pains, vomiting, loose stool, neurological symptoms. Recovery occurs after 7-10 days from the onset of the disease. There are reports that the number of forms of legionellosis by type of acute respiratory disease is more than the number of forms with lung tissue damage in dozens of times.

Acute feverish diseases with exanthema (Fort Bragg fever) are manifested by increased body temperature, catarrh of the respiratory tract and spotted-papular rashes throughout the body.

Diagnosis of legionellosis

Legionellosis can be suspected if it is found in light darkening zones or spotted interstitial infiltrates, which persist for a long time and often progress, despite active treatment with antibacterial drugs from the penicillin group.

For laboratory confirmation, the material from the patient is inoculated on Mueller-Hinton agar with the addition of iron salts and L-cystine or infect guinea pigs with subsequent infection of chick embryos. As a rapid diagnosis using the method of direct immunofluorescence, with which you can detect the agent directly in sputum, bronchial flushes or in the prints of biopsies of bronchi and lungs, obtained with bronchoscopy.

For serological diagnosis, ELISA, an indirect method of immunofluorescence or a microagglutination reaction are used.

Differential diagnostics

Pneumonic form of legionellosis must be differentiated with severe pneumonia caused by viral-bacterial associations, chlamydia and mycoplasmas.

Cases of legionellosis as catarrh of the respiratory tract differentiate with ARI. Correct diagnosis in all cases is possible only on the basis of the results of laboratory research methods.

Treatment of legionellosis

As an etiotropic treatment, antibiotics are used. The best effect is achieved with the appointment of macrolides in combination with probiotics (acipol, etc.).

Pathogenetic and symptomatic treatment is carried out according to generally accepted principles.

Prevention of legionellosis

Quarantine measures are ineffective. Crucial is the study of water in the air conditioning and disinfection by raising the water temperature to 60 ° C, allowing you to clean the system of legionella.

For the prevention of hospital legionellosis, it is necessary to thoroughly clean and sterilize medical equipment, especially devices used in the treatment of respiratory diseases (cannula, tracheotomy tubes, ventilators).

Currently, active immunization is being developed with the help of vaccine preparations.

[1], [2], [3]