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Avian Influenza - Diagnosis
Last reviewed: 03.07.2025

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Correct diagnostics of bird flu at an early stage is the starting point for organizing targeted treatment, timely implementation of anti-epidemic measures and determining the prognosis. However, there are certain objective difficulties in diagnosing bird flu associated with the similarity of the clinical picture of this disease and other ARVI.
Preliminary diagnosis of influenza A (H5N1) can be based on the following epidemiological history and clinical manifestations:
- the presence of reports of outbreaks of influenza A (H5N1) among the bird and animal population or cases of death of poultry in the patient's region of residence;
- contact with a sick person who has been confirmed to be infected with the influenza virus (H5N1) seven days before the onset of the first clinical signs;
- contact with a patient with acute respiratory disease of unclear etiology, including one that ended fatally, seven days before the appearance of the first clinical signs;
- the patient's indication of travel to a country or territory where there are reports of an unfavorable epidemiological and/or epizootic situation with regard to influenza A (H5N1);
- the presence of a professional risk of infection of the patient;
- high fever combined with difficulty breathing, cough;
- diarrhea (in the absence of blood in the feces).
A definitive diagnosis can be made after laboratory confirmation.
Laboratory diagnostics of avian influenza is based on methods of virological research, serological reactions, immunofluorescence analysis and PCR.
Differential diagnosis of avian influenza in humans
Considering that influenza A (H5N1) causes symptoms of respiratory tract damage, differential diagnostics of bird flu with other acute respiratory viral infections is necessary: “traditional” influenza (A, B), severe acute respiratory syndrome, parainfluenza, respiratory syncytial, adenovirus and enterovirus infections, as well as legionellosis and ornithosis.
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