What are the clinical manifestations of influenza? What should we do if we have influenza?

1. Typical Flu

Symptoms of systemic poisoning such as high fever, chills, headache, body pain, fatigue, and loss of appetite are obvious, and respiratory symptoms are mild. A small number of patients may have eye symptoms such as nasal congestion, runny nose, photophobia, and tearing. Cough, sternal discomfort or burning, dry throat, and sore throat are also common. The body temperature can reach 40°C, the face is red, and the pharynx and conjunctiva are mildly congested. There may be dry rales in the lungs. The fever reaches its peak over 1~2 days and subsides within 3~4 days. Respiratory symptoms are obvious after the fever subsides, and disappear after 3~4 days, but fatigue may last for 1~2 weeks. This type is the most common. Mild patients have a fever of no more than 39°C, mild symptoms, and a course of 2~3 days.

2. Influenza virus pneumonia

Influenza virus infection can turn from simple type to pneumonia type, or it can directly manifest as pneumonia type. Pneumonia type is caused by the continued spread of influenza virus infection from the upper respiratory tract to the lower respiratory tract. Primary influenza virus pneumonia is prone to occur in patients with underlying lung and heart disease (especially rheumatic heart disease, left atrial valvular stenosis), pregnant women or immunocompromised patients, but up to half of the case reports have not confirmed the underlying disease. After the onset of typical pneumonia influenza, high fever persists, and symptoms such as difficulty breathing, cyanosis, severe cough, foamy mucus sputum or blood in sputum appear rapidly; physical examination found that the breathing sounds of both lungs were low and full of wheezing, but there were no actual signs of change.

Chest X-ray shows flocculent shadows scattered on both sides of the lungs, spreading from the hilum to the periphery; its manifestations are related to adult respiratory distress syndrome (ARDS). Similarly, patients may die from heart failure or peripheral circulatory failure. The course of the disease can be as long as 3 to 4 weeks. Blood gas analysis shows obvious hypoxia. Influenza virus is easily isolated in sputum, and many neutrophilic multinucleated cells can be seen in sputum smear Gram stain; but no pathogenic bacteria grow in sputum and blood culture, antibacterial treatment is ineffective, and the mortality rate can exceed 50%. Influenza often affects the lower respiratory tract in infants and the elderly, especially pneumonia. About a quarter of hospitalized children with lower respiratory tract infection are caused by influenza virus. The incidence of influenza pneumonia and bronchitis in the elderly increases with age, with an incidence of 36% in the 60-69 age group and 73% in the group over 70 years old. Influenza pneumonia in the elderly often lacks initial symptoms and is easily overlooked. Pneumonia is often found to be accompanied by significant dehydration, acidosis, or impaired consciousness and other critical conditions.

3. Toxic and gastrointestinal

Poisoning is very rare. The virus invades the nervous system and cardiovascular system and causes poisoning symptoms. Clinically, there are symptoms of encephalitis or meningitis, mainly manifested by high fever, coma, delusions in adults, convulsions in children, irritation of the meninges, and a slight increase in the number of cerebrospinal fluid cells. In some cases, blood pressure may drop or shock may be caused by vascular nervous system disorders or adrenal hemorrhage. Gastrointestinal influenza is very common in children, with nausea, vomiting, diarrhea, and abdominal pain as the main symptoms, and generally recover within 2 to 3 days.