I. Influenza (influenza , short for flu).
Is caused by the influenza virus acute respiratory infectious disease, is one of the major public health problems facing mankind. According to statistics, the annual incidence of influenza is 10% to 30%, its epidemiology is the most significant feature: sudden outbreak, rapid spread, the spread of a wide range. Influenza epidemic has certain seasonality. In the north of China, it often occurs in winter, while in the south it occurs in winter and summer. The incidence of influenza is high and the population is generally susceptible. Influenza viruses have two types of glycoprotein protrusions, namely hemagglutinin (HA ) and neuraminidase (NA ). Depending on their antigenicity, influenza viruses are classified into three types: A, B, and C. Influenza A viruses are often found in epidemic form. Influenza A viruses often appear in epidemic form and can cause worldwide pandemics; B viruses often cause local outbreaks of influenza; C viruses mainly appear in epidemic form. Because the antigenicity of influenza viruses mutates rapidly, humans cannot obtain lasting immunity. Influenza has severe clinical symptoms, rapid onset, high incidence of complications, and can cause death, mostly among the elderly, the young, the sick, or those with chronic underlying diseases. Vaccination of these populations is the main method to control influenza. The population develops immunity through infection or vaccination, but there is no protection against new mutant strains of the virus. Anti-influenza virus therapy is currently considered to be an important tool for influenza control. And early diagnosis is important to carry out effective and specific pathogenic treatment.
China is a high-incidence area for influenza, and three of the four worldwide pandemics in the 20th century originated in China. In order to improve the early diagnosis and treatment of influenza, and to reduce the great harm caused by influenza to the society, it is important to develop practical guidelines for influenza diagnosis and treatment that are suitable for use by clinicians.
II. Clinical manifestations, diagnosis and differential diagnosis of influenza.
(A) Clinical manifestations
The incubation period of influenza is generally 1 to 3 days. The onset of the disease is more acute, mainly with systemic symptoms of poisoning, respiratory symptoms are mild or not obvious. Fever usually lasts 3-4 days, but fatigue and weakness can be 2-3 weeks. According to the clinical manifestations, it can be divided into simple type, pneumonia type, poisoning type, and gastrointestinal type.
(ii) Diagnosis
Epidemiological data is one of the main bases for the diagnosis of influenza, and it is not difficult to diagnose with typical clinical manifestations, but it is more difficult to diagnose in the early stage of epidemic, epidemic or light cases. Laboratory tests are often needed to confirm the diagnosis. The main diagnostic basis is as follows.
1 .Epidemiological history.
In the epidemic season, a large number of patients with upper respiratory tract infection in a unit or area or a significant increase in hospital outpatients and emergency patients with upper respiratory tract infection.
2, clinical symptoms.
Acute onset, chills, high fever, headache, dizziness, body aches, fatigue and other signs of toxicity. May be accompanied by sore throat, runny nose, lacrimation, cough and other respiratory symptoms. In a few cases, there is loss of appetite, accompanied by gastrointestinal symptoms such as abdominal pain, bloating, vomiting and diarrhea. Clinical symptoms of infant influenza are often atypical and can be seen as high fever convulsions; some children show laryngotracheobronchitis, and in severe cases, airway obstruction; although neonatal influenza is rare, a bite ____ often shows septic manifestations, such as drowsiness, refusal of milk, apnea, etc., often accompanied by pneumonia, with a high mortality rate.
3, laboratory tests.
( 1 ) peripheral blood image: total white blood cell count is not high or reduced, lymphocytes are relatively increased.
( 2 ) virus isolation: nasopharyngeal secretions or oral rinses isolated influenza virus.
( 3 ) serological examination: a 4-fold or more elevated serum anti-influenza virus antibody titer in both the early stage of disease and the recovery period can help retrospective diagnosis
( 4 ) The patient’s respiratory epithelial cells were positive for influenza virus antigen.
(5) Positive influenza virus antigen was detected in the specimen after overnight proliferation of sensitive cells for 1 generation.
4.Diagnosis classification.
( 1 ) suspected cases: with epidemiological history and clinical symptoms.
( 2 ) confirmed cases: suspected cases, while laboratory tests meet (2) or (3) or (4) or (5).
(C) differential diagnosis
(1) Common cold: the clinical manifestations of influenza are not specific and easily confused with common cold. In addition to attention to the collection of epidemiological data, usually influenza systemic symptoms than the common cold, while the common cold respiratory tract local symptoms are heavier.
2, other systemic or upper respiratory tract infectious diseases.
III. Treatment of influenza
The basic principles of influenza treatment
1.Isolation of patients, strengthening ventilation and air disinfection in public places during the epidemic.
2, early application of anti-influenza virus drug therapy: anti-influenza virus drug therapy only early (within 1 or 2 days of the onset of the disease) to achieve the best efficacy.
3, strengthen supportive treatment and prevent complications: rest, drink more water, pay attention to nutrition, diet should be easy to digest, especially in children and elderly patients should pay more attention. Close observation and monitoring of complications, antibiotics are only indicated when there is clear or sufficient evidence of secondary bacterial infection.
4, the rational application of symptomatic drugs: early application of anti-influenza virus drugs can mostly be effective in improving symptoms. If the disease is late or there is no condition to apply antiviral drugs, symptomatic treatment can be applied, such as antipyretic drugs, drugs to relieve nasal mucosal congestion, cough expectorant drugs. Aspirin or aspirin-containing drugs and other salicylic acid preparations are contraindicated in children because they are associated with hepatic and neurological complications of influenza, namely Reve’s syndrome, which can occasionally be fatal.