Influenza - Symptoms

Influenza is an acute disease with a short incubation period (from 10-12 hours to several days).

Flu always begins acutely. Typical flu symptoms appear: a feeling of exhaustion, muscle and joint aches, chills. The temperature can rise in the range from subfebrile values to hyperthermia within a few hours, reaching a maximum on the first day of the disease. The severity of the fever reflects the severity of intoxication, but these concepts cannot be completely identified. Sometimes, at a high temperature, signs of intoxication are weakly expressed (often in young people who have fallen ill with the flu caused by the influenza A - H1N1 virus). Hyperthermia in them is short-lived, and subsequently the disease proceeds with a moderate degree of severity.

The duration of the febrile period is 2-5 days, rarely up to 6-7 days, and then the temperature decreases lytically.

The first symptoms of flu are headache, which is the main sign of intoxication. Headache is usually localized in the frontal part, especially in the area of the superciliary arches, sometimes it is retro-orbital. In elderly people, headache is often diffuse. Its severity varies, but in most cases it is moderate. Severe headache combined with insomnia, hallucinations, repeated vomiting occurs in patients with a severe course of the disease, often accompanied by meningeal syndrome. In adults, unlike children, convulsive syndrome rarely develops. During a painful dry cough, combined with vomiting, very severe pain occurs in the upper parts of the rectus abdominis muscles and intercostal muscles on the line of attachment of the diaphragm to the chest.

Catarrhal syndrome is the second leading syndrome in flu (in most patients it is represented by tracheitis), but it often recedes into the background. In some cases this syndrome is weakly expressed or absent. The duration of the catarrhal syndrome is 7-10 days, cough persists the longest. The mucous membrane of the nasopharynx is dry, hyperemic, edematous. Swelling of the nasal conchae makes breathing difficult. Rhinorrhea is scanty or absent in the first days, later serous, mucous or bloody discharge from the nose appears. From the first day of the flu, there is a soreness and dryness behind the breastbone. The mucous membrane of the back wall of the pharynx is hyperemic and dry.

The heart sounds are muffled, sometimes a systolic murmur is heard at the apex. Relative bradycardia occurs in a third of patients, and in 60% of patients the pulse corresponds to body temperature. Tachycardia is sometimes detected. Persistent tachycardia at the height of the disease gives an unfavorable prognosis, especially in older people with chronic diseases of the heart, blood vessels and respiratory organs. In patients with influenza, a decrease in blood pressure is detected. In patients with hypertension, a hypertensive crisis may develop during the convalescence period.

The tongue is thickly coated with white plaque, not thickened. Appetite is decreased. The presence of dyspeptic syndrome against the background of fever and intoxication excludes the presence of influenza and is caused by the development of another infectious disease of viral (enteroviruses, rotaviruses, Norwalk viruses) or bacterial etiology. The liver and spleen are not enlarged with influenza. Urination disorders do not occur with uncomplicated influenza.

In uncomplicated influenza, leukopenia with eosinopenia and neutropenia with a slight shift of band cells to the left, as well as relative lymphocytosis and monocytosis often occur. The degree of leukopenia is directly proportional to the severity of toxicosis. ESR is normal in most patients. X-ray examination of the lungs in the acute period of the disease reveals an increase in the vascular pattern.

[ 1 ], [ 2 ], [ 3 ]

Classification of influenza

Symptoms of influenza can vary significantly depending on the age of the patient and the state of their immune system; the serotype of the virus, its virulence, etc.

The following are distinguished:

• uncomplicated influenza;
• complicated flu.

According to the severity of the course, the following are distinguished:

• lung;
• moderate severity;
• heavy.

Sometimes a lightning-fast course of flu is distinguished. The severity of uncomplicated flu is determined by the severity and duration of intoxication.

[ 4 ], [ 5 ], [ 6 ]

Complications of influenza

Pneumonia is one of the frequent complications of influenza. Pneumonias that develop against the background of a viral infection are classified as primary viral-bacterial (most often streptococcal and staphylococcal etiology). They often develop in patients of the "high risk" group: with chronic lung and heart diseases, and in the elderly. Staphylococcal and pneumococcal pneumonias against the background of severe toxicosis, typical of influenza, are difficult to diagnose. Staphylococcal pneumonia is characterized by a "creeping" nature and a tendency to destroy lung tissue.

Post-influenza pneumonia, developing at the end of the 1st - beginning of the 2nd week of the flu, is easier to diagnose. Antibacterial treatment gives good results. Pneumonia can be of both interstitial and focal nature. Post-influenza pneumonia is dangerous for older people. In such patients, the disease can proceed as a confluent pseudolobar pneumonia.

Lightning flu with a severe course can end in death on the 2nd-3rd day (acute hemorrhagic pulmonary edema develops against the background of severe intoxication). From the first hours, high fever occurs, shortness of breath and cyanosis quickly increase. A lot of bloody, sometimes foamy, sputum appears. X-rays reveal foci of darkening of a round or irregular shape. Muffling of the percussion sound is absent or expressed insignificantly. In the following days, against the background of high temperature and severe shortness of breath, DN increases. hypoxic coma and collapse develop.

A severe complication of influenza is cerebral edema. It is characterized by: severe headache, vomiting, confusion, loss of consciousness, increased blood pressure, decreased respiration, bradycardia, meningeal syndrome, congestion of the fundus.

Frequent complications of influenza are sinusitis and otitis; pyelonephritis and pyelocystitis occur less frequently. Other complications are also possible: diencephalic syndrome, meningoencephalitis and asthenovegetative syndrome. The severity of the course and outcome of the disease are influenced by concomitant chronic pathologies and neuroendocrine disorders.

[ 7 ], [ 8 ], [ 9 ], [ 10 ]

Mortality and causes of death in influenza

Influenza has a mortality rate that does not exceed 1-2%. Severe symptoms of influenza may indicate the following conditions: cerebral edema, hemorrhagic pulmonary edema, acute vascular insufficiency.