Influenza: diagnosis
Last reviewed: 23.04.2024
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Diagnosis of influenza during the epidemic outbreak is not difficult. It is based on the detection of typical manifestations of the disease (intoxication, catarrhal syndrome mainly in the form of tracheitis).
Rapid diagnosis of influenza is based on the method of immunofluorescence (identify virus antigens in smears and prints from the nose). To make the final diagnosis it is necessary to isolate the pathogen from the patient's clinical material by infecting cell cultures or chick embryos and to identify the isolated virus. Retrospectively, the diagnosis is established by increasing the titer of antibodies in paired blood sera in patients.
[Indications for hospitalization
Hospitalization is subject to patients with severe or complicated course of influenza, as well as a number of concomitant diseases: severe forms of diabetes mellitus, chronic ischemic heart disease, chronic nonspecific lung diseases, blood diseases, CNS diseases.
Syndromic indications for hospitalization include:
- high fever (above 40 ° C);
- impaired consciousness;
- repeated vomiting;
- meningeal syndrome:
- hemorrhagic syndrome;
- convulsive syndrome;
- respiratory insufficiency;
- cardiovascular failure.
Hospitalization and isolation of patients are also carried out according to epidemiological indications. (Hostels, boarding schools, children's homes, hotels, transport, military collectives, institutions of the penitentiary system.)
Differential diagnosis of influenza
Differential diagnosis of influenza is carried out with two groups of infectious diseases:
- diseases that occur with the catarrhal-respiratory syndrome;
- diseases characterized by early development of febrile-intoxication syndrome.
The first group includes other SARS, in which (in contrast to the flu) cough, runny nose, pain and sore throat precede the fever and are not accompanied by general symptoms of intoxication (absent or occur on 2-3 days of the disease, are moderately expressed, however, may last longer than with influenza). The combination of fever, intoxication and lymphadenopathy with catarrhal phenomena allows to exclude influenza and assume the presence of measles, iersiniosis or infectious mononucleosis. Since the digestive organs are not involved in the pathological process in the course of the flu, this allows to exclude this disease from a combination of fever and catarrhal phenomena with dyspeptic syndrome. In this case, the presence of viral diarrhea (rotavirus, norvolk-viral ), as well as iersinnozov or measles in adults.
With many acute forms of infectious diseases, an influenza-like clinical picture is expressed in the first 1-2 days of the course. In this case, it is necessary to take into account the distinctive features of influenza: a strong chill is rarely detected; peak of intoxication on the 1-2 day of the course of the disease; lymphadenopathy, an increase in spleen and liver never occurs; with 2-3 days expressed tracheitis; duration of fever (with uncomplicated form) 3-4 days (no more than 5-6 days): a relative bradycardia or correspondence of the heart rate to the body temperature level is characteristic.
In practice, the flu is mistakenly diagnosed with staphylococcal diseases (scarlet fever, angina, erysipelas), community-acquired pneumonia (before the appearance of characteristic symptoms), meningococcal infection, malaria, pyelitis, rickettsiosis, typhoid fever and salmonellosis (before dyspeptic syndrome), leptospirosis (in warm weather year), viral hepatitis A, hemorrhagic fevers, trichinosis.
In difficult cases for diagnosis, the doctor must assess the severity of the patient's condition, the need and timing of a re-examination or emergency hospitalization. At the same time, antibiotics and antipyretic drugs should be avoided, as they can make it more difficult to further diagnose and create the illusion of improving the patient's condition.