Psittacosis is a chlamydial infection that occurs with a predominant lesion of the respiratory system. Clinical manifestations include fever-intoxication syndrome, pneumonia, conjunctivitis, hepatolienal syndrome, signs of neurotoxicosis and meningism. The diagnosis of psittacosis is confirmed by the data of serological studies (IFA, IFT, HI, ELISA), sputum microscopy, lung radiography. Etiotropic therapy of psittacosis is carried out with antibacterial drugs from the group of macrolides, fluoroquinolones and tetracyclines; additionally, bronchodilators, antitussive drugs, vitamins are used.
Psittacosis (respiratory chlamydia, ornithosis, parrot disease) is a zoonotic infection, the specific pathogens of which are chlamydia, and the source is birds. Psittacosis is a widespread disease, which is caused by the migration of birds. In the structure of acute pneumonia recorded in various regions of the world, 10-20% of cases have an ornithotic etiology. This fact requires an increase in the level of epidemic alertness regarding psittacosis on the part of specialists in the field of pulmonology. In most cases, sporadic cases of psittacosis are recorded; less often – family, group and industrial outbreaks. Among those with psittacosis, middle-aged and older patients predominate; infection develops relatively infrequently in children.
The disease is caused by the obligate intracellular parasite Chlamydophila psittaci. The peculiarities of the vital activity of chlamydia determine the specifics of the course of psittacosis. Such special properties include the ability of the pathogen to multiply inside cells, the formation of the L-form and the preservation of virulence in various conditions, the release of exo- and endotoxin, tropism to the cells of the respiratory tract and the system of mononuclear phagocytes, etc. The pathogen of psittacosis shows relative stability in the external environment, tolerates low temperatures well. At the same time, rapid inactivation of chlamydia occurs when heated, exposed to chlorine-containing disinfectants, ultraviolet light, antiseptics.
The natural source and reservoir of ornithotic infection are wild and domestic, including ornamental birds, which are bacterial carriers or carry the disease in the form of rhinitis or acute intestinal infection. Carriers of Chlamydophila psittaci can be over 150 species of birds, more often – parrots, canaries, ducks, chickens, turkeys, crows, pigeons (in cities, the infection of pigeons with psittacosis reaches 50-80%). Birds can transmit the pathogen to offspring for 2 or more generations. The pathogen of psittacosis enters the environment together with nasal secretions and feces of birds. Human infection can occur in various ways: aerogenic (when inhaling the pathogen with dust), household contact (through feathers, eggs, household items contaminated with the pathogen) and fecal-oral (when eating infected food or introducing the pathogen into the mouth from dirty hands). The group of increased risk for the incidence of psittacosis includes workers of poultry farms, poultry farms, pet stores, breeders of pigeons and ornamental birds, as well as rural residents who keep poultry in their farmstead.
The main target of the pathogen of psittacosis in the human body are the cells of the cylindrical epithelium of the respiratory tract, lymphoid and reticulogistiocytic cells, in which chlamydia multiplies and accumulates. After 2-3 days, the affected cells are destroyed, and chlamydia, their toxins and waste products enter the bloodstream, causing symptoms of allergy and intoxication. Hematogenic spread of pathogens throughout the body leads to damage to the lungs, myocardium, brain, liver. Pathomorphological changes in internal organs in psittacosis include focal-drain bronchopneumonia, an increase in peribronchial and bifurcation lymph nodes, hepatomegaly and splenomegaly, dystrophic changes in parenchymal organs. Since chlamydia are prone to prolonged intracellular persistence, psittacosis often takes a prolonged recurrent course with the formation of lung atelectasis and the development of focal fibrosis or diffuse pneumosclerosis.
The clinical course of psittacosis goes through an incubation period (1-3 weeks), a prodromal period, a period of clinical manifestations and a period of recovery. The disease can occur in a respiratory, flu-like, typhoid, meningeal and generalized form, as well as in an acute or chronic variant.
Before the manifestation of specific symptoms of acute psittacosis, prodromal phenomena are noted for 3-5 days, characterized by malaise, general weakness, nausea, loss of appetite, subfebrility. Following this, a fever develops with a temperature of up to 39-40 ° C, which decreases lytically after a few days. In the febrile period, thirst, dry mouth, myalgia and arthralgia are expressed. Mild catarrhal phenomena are noted: tickling and sore throat, runny nose, hyperemia of the pharyngeal mucosa, laryngitis. Due to the tropicity of the pathogen of psittacosis to the vascular endothelium, conjunctivitis occurs, vascular injection of the sclera, nosebleeds, skin rash of a spotty-papular or roseolous nature.
On 3-5 days, signs of lung damage are added to the general infectious symptoms: chest pain, dry, and then a productive cough with mucopurulent sputum. Radiologically, signs of interstitial, small- or large-focal, lobular ornithotic pneumonia are determined. By the end of the first week of the disease, the liver increases. Ornithosis is characterized by damage to the nervous system with signs of neurotoxicosis: headache, adynamia, insomnia, depression, in severe cases – hallucinations, delirium, euphoria. It is possible to develop serous meningitis with a benign course.
The flu-like form of psittacosis is characterized mainly by symptoms of general intoxication. Typhoid-like infection occurs with a remitting type of fever, hepatosplenomegaly and neurotoxic manifestations. With the meningeal form of ornithosis, the symptoms of meningism come to the fore. In any of the clinical forms of psittacosis, convalescence stretches for 2-3 months; during this period, asthenization, rapid fatigue, decreased ability to work, arterial hypotension, signs of vegetative-vascular dystonia (acrocyanosis, palmar hyperhidrosis, tremor, shivering of the extremities) persists. In 10-12% of patients, psittacosis takes a chronic course, more often in the form of chronic bronchitis or pneumonia with prolonged subfebrility, enlarged liver and spleen, asthenovegetative syndrome.
Rare complications of psittacosis include: hepatitis, nephritis, myocarditis, polyneuritis, iridocyclitis, thyroiditis, etc. In pregnant women, psittacosis can cause spontaneous termination of pregnancy.
Diagnosis and treatment
The basis for the clinical diagnosis is provided by the data of the epidanamnesis (close contact with birds, group morbidity) and characteristic symptoms (fever, pneumonia, hepatolienal syndrome, etc.). For laboratory confirmation of psittacosis, microscopic examination of sputum, serological diagnostics (IFA, IFT, HI, ELISA), examination of bronchial biopsies obtained during bronchoscopy, a bioassay on chicken embryos.
Ornithotic pneumonia is diagnosed by physical examination and lung-x-ray. With meningeal symptoms, a spinal puncture is performed with a study of cerebrospinal fluid. It is possible to conduct and analyze an intradermal allergic test with an inactivated culture of the pathogen of ornithosis. Differential diagnosis is aimed at excluding acute respiratory viral infections, influenza, atypical pneumonia, infectious mononucleosis, brucellosis, Q fever, tuberculosis, legionellosis, deep mycoses (aspergillosis, histoplasmosis, nocardiosis, coccidioidosis).
Complex treatment of ornithosis consists of etiotropic, pathogenetic and symptomatic therapy. The basic drugs for the specific therapy of ornithosis are tetracycline antibiotics, macrolides, fluoroquinolones with antichlamydial activity. In the acute form of ornithosis, the duration of the antibacterial course is 10-14 days; in the chronic course, 2-3 courses of antibiotic therapy are carried out with an interval of 7-10 days and a change of the drug. Pathogenetic therapy of ornithosis includes the appointment of immunomodulators, immunostimulators, multivitamins, detoxification measures. The symptomatic orientation is the reception of antipyretics, antitussives, mucolytics.
Prognosis and prevention
The outcome of ornithosis is usually favorable. However, about a quarter of patients develop relapses of the disease in the early (2-4 weeks) or late (4-6 months). With timely treatment, complications of ornithosis rarely occur. Among the most dangerous of them, associated with the risk of death, are acute heart failure, PE. Immunity after ornithosis is unstable, repeated cases of infection are possible.
Non-specific preventive measures include limiting contact with birds, strengthening veterinary control over the maintenance of birds on poultry farms and in zoos, and the destruction of infected livestock. Disinfection is carried out in the foci of ornithosis; persons who have been exposed to sick birds are subject to medical supervision for 30 days with chemoprophylaxis of infection.