Influenza A is highly contagious, and its antigens can easily mutate. In addition, it is mainly transmitted through respiratory tract, which can easily cause epidemics and pandemics. There is no obvious seasonality during the pandemic, and sporadic epidemics can occur in winter, spring, and summer.

Epidemics often occur suddenly, spread rapidly, and have a high incidence rate. The epidemic process lasts for a short time, but for influenza A specific There is currently no authoritative data. The main influenza A (H1N1) Take influenza A (H3N2) as an example to introduce the relevant epidemiology.

Influenza A is highly contagious and can spread widely among people.

·Source of infection: patients and asymptomatic infected persons are the source of infection. Influenza A virus can be spread from 2 days before symptoms appear to about 1 week after symptoms appear.

·Transmission route: Mainly through droplets through the respiratory tract, It can also be transmitted through direct or indirect contact with respiratory secretions, body fluids and items contaminated with the virus.

·Susceptible groups: People are generally susceptible to influenza A, and will acquire the same subtype after infection. There is a certain degree of immunity, but there is no cross-immunity between different subtypes, so the human body can get sick repeatedly. Obesity, the elderly, children, and pregnant women are relatively high-risk groups and require special attention.

The classification of influenza A is mainly related to the type of influenza A virus. According to different H and N antigens, Influenza A is now divided into 18 H subtypes (H1~H18) and 11 N subtypes (N1~N11). Among them, H1, H2, H3 and N1, N2 subtypes are unique to human influenza viruses.

H antigen and N antigen can be combined into 144 subtypes. Among them, only H1N1, H2N2, and H3N2 mainly infect humans. At present, influenza A in clinical practice can be mainly divided into two categories: influenza A H1N1 and influenza A H3N2.

Influenza A is mainly caused by infection with influenza A virus through multiple channels. (If the patient sneezes and coughs, droplets are spread) It can also be transmitted through direct or indirect contact with mucous membranes such as the mouth, nose, eyes, etc. Transmission can also occur through contact with items contaminated with influenza A viruses.

Factors such as low immunity, changes in hot and cold weather, and dry weather are common causes of influenza A.

The incubation period of influenza A is generally within 7 days, mostly 1 to 3 days.

The onset is acute and the symptoms are non-specific, with fever (body temperature often exceeding 38°C) and cough as the main symptoms. In addition, it may be accompanied by sore throat, runny nose, fatigue, headache, and general muscle aches.

Patients with mild influenza A have mild clinical symptoms and may only have mild upper respiratory tract symptoms. There is no fever and is often self-limiting. In a few severe patients, the body temperature can rise rapidly to above 39°C. If it persists for more than 3 days, respiratory symptoms will be significantly aggravated, with shortness of breath, Increased heart rate, cyanosis of the lips, and mental and neurological symptoms such as unresponsiveness, drowsiness, and restlessness may also occur.

Newborns and infants may have atypical flu-like symptoms, which may include low-grade fever, Feeding difficulties, lethargy, dehydration, shortness of breath, etc. require special attention and observation.

Influenza A patients mainly suffer from upper respiratory tract symptoms. Therefore, the first choice is to go to the respiratory department, but you can also go to the fever clinic or the infection department.

The diagnosis of influenza A is relatively clear, based on the patient’s epidemic history, Flu-like symptoms can be confirmed by combining relevant laboratory test results.

·Epidemic history: During the influenza A epidemic, there were cases within 7 days of onset of illness A history of epidemics that has been to an epidemic site, or close contact with an infected person.

·Flu-like symptoms: including fever, cough, sore throat, runny nose, fatigue, muscle aches and headache.

·Laboratory examination: pathogenic examination to isolate influenza A from respiratory specimens Viruses or influenza A virus nucleic acid may be detected, such as influenza A H1N1 virus and influenza A H3N2 virus; serum antibody test revealed double sera The level of specific antibodies to influenza A virus increased 4-fold or more.

After the patient sees a doctor, the doctor usually checks the patient’s body temperature, Whether there are abnormalities in blood pressure, pulse, mental status, and whether there is pharyngeal congestion, Signs such as tonsil enlargement can help diagnose the disease.

Patients with influenza A need to undergo routine blood tests, blood biochemistry tests, Pathogenic examination, serum antibody examination and chest imaging examination, Among them, the results of pathogenic examination and serum antibody test can confirm the diagnosis.

laboratory tests

Film degree exam

If the patient has symptoms such as shortness of breath, rapid heart rate, cyanosis of the lips, etc., Corresponding supportive treatment, such as oxygen therapy and mechanical ventilation, should be given promptly. If the pulse disappears and shock occurs, cardiopulmonary resuscitation should be performed promptly to save the patient's life.

Suspected and confirmed patients should be treated in isolation, and patients should pay attention to rest. Drink more water, pay attention to nutrition, and closely observe changes in the condition. If there are chills, Keep warm when you are afraid of the cold, and when your body temperature is above 38.5℃ Take a warm water bath and apply cold compresses to your forehead and armpits to cool down.

Due to large individual differences, there is no absolute best, fastest or most effective medication. In addition to commonly used over-the-counter drugs, the most appropriate drug should be selected based on the individual situation under the guidance of a doctor.

Due to the large individual differences, medication should be fully combined with individual circumstances under the guidance of a doctor to select the most appropriate drug treatment.

·Antiviral drugs: For patients with severe clinical symptoms or severe pneumonia and acute respiratory Influenza A patients with complications such as distress syndrome and pulmonary hemorrhage should be treated promptly Neuraminidase inhibitors are used for antiviral treatment. Commonly used drugs include oseltamivir, Mabaloxavir, zanamivir, peramivir, etc. are best taken within 36 hours of onset of illness.

·Symptomatic drugs: For patients with influenza A who have mild clinical symptoms and no complications, and whose condition tends to be self-limiting, There is no need for anti-viral treatment, just take antipyretic, cough-relieving and expectorant drugs to treat the symptoms. Commonly used antitussive and expectorant drugs include acetylcysteine ​​tablets, compound licorice tablets, and Suhuang cough capsules. Antipyretic drugs include acetaminophen tablets, ibuprofen granules, indomethacin tablets, etc. You must strictly follow the doctor's instructions when taking them.

Influenza A patients with low immunity or underlying diseases may have severe disease progression. Complicated by severe pneumonia, acute respiratory distress syndrome, pulmonary hemorrhage, pleural effusion, Pancytopenia, renal failure, sepsis, shock and Reye syndrome, Respiratory failure and multiple organ failure can even lead to death.

·Diet: Encourage patients to drink more water, ensure a light diet, eat regularly, and eat regularly. Pay attention to rich and balanced nutrition; for children who have difficulty eating, add orange juice, Fruit milk, grape juice and other electrolyte-rich drinks; comatose patients or those unable to eat due to invasive ventilation Patients can use a nasogastric tube to feed water or follow the doctor's instructions to supplement fluids through intravenous injection.

·Exercise: Appropriate physical exercise, but pay attention to the balance between work and rest to avoid excessive fatigue, which will help strengthen your physical fitness.

·Lifestyle: Ventilate the room regularly and pay attention to rest; add or remove clothes in time, Keep warm and prevent colds; pay attention to personal hygiene, wash hands, bathe and change clothes frequently.

·Emotional psychology: Patients should avoid worrying too much about the disease, face the disease squarely, and maintain a comfortable mood; Family members should provide psychological support to patients and provide more understanding, care and guidance to patients.

Patients with influenza A should do a good job in monitoring their condition. If there is a sudden high fever and the temperature persists and does not fall below 39°C, When accompanied by symptoms such as shortness of breath and rapid heart rate, you should inform your doctor immediately to determine whether the condition is progressing. In order to facilitate timely detection and timely control, and reduce the occurrence of complications.

Influenza A is highly contagious, and isolation and protection are the key to preventing the spread of the virus. If the patient is under observation at home, he should stay in a single room as much as possible to reduce the frequency of contact with family members.

Influenza A is an acute respiratory infectious disease caused by influenza A virus infection and is highly contagious. Generally, effective prevention can be achieved by controlling the source of infection, cutting off transmission routes, and protecting susceptible groups.

·Control the source of infection: Patients and suspected patients should be isolated from the respiratory tract. For example, a single room is guaranteed for one person during home observation. If the patient is a confirmed inpatient, multiple people can share the same room. Patients should also pay attention to personal hygiene, wash hands frequently, and ensure indoor ventilation. Avoid going to crowded or unventilated places, and reduce the frequency of outings.

·Cut off transmission routes: Family members, especially high-risk groups, should try to avoid Close contact with influenza A patients, and you must raise awareness of precautions during the contact process. Strengthen personal protection. If you have had direct contact with patients or handled patients After removing items and respiratory secretions, you need to use disinfectants and detergents to disinfect your hands.

·Protect susceptible groups: Mainly vaccination with inactivated influenza A vaccine to prevent influenza A The best method. Since the immunity ranges partially overlap, vaccinators generally choose trivalent Or just get the quadrivalent influenza vaccine. Generally, people over 3 years old need to be nearby Go to medical and health institutions to get vaccinated, but some people do not meet the vaccination requirements. If you consult your doctor and it is clear that you cannot vaccinate, you should focus on the first two ways for prevention.