With the Spring Festival gatherings, the risk of this infectious disease has soared! Experts personally provide protection guidelines

During the Spring Festival holiday, people visit relatives and friends and often have gatherings. Therefore, we should pay attention to prevent respiratory infectious diseases - influenza. How to prevent influenza? How to reduce the possibility of severe illness and complications? Everyone is equal in the face of respiratory infectious diseases. Everyone knows some basic knowledge that can make our respiratory tract healthier.

What does the respiratory tract look like?

To understand the lungs, we must first understand the respiratory tract. The respiratory tract starts from the nose, then goes to the nasal cavity, pharynx, trachea, bronchus and alveoli. The lungs are like an upside-down tree. We can see the "trunk" and "branches". The "branches" are further divided into finer "twigs" and then into the alveoli. Just like the sycamore tree, the alveoli are equivalent to the "leaves". There are 23 levels from the trachea to the alveoli. The main function of the lungs is to inhale oxygen and exhale carbon dioxide.

The trachea and bronchus are mainly used for ventilation, while the alveoli are mainly used for gas exchange. The alveoli are mainly used for the exchange of qi and blood. They supply the fresh oxygen inhaled to the blood, ensuring the normal functioning of the heart, brain, liver and other organs. At the same time, they discharge the metabolic waste gas of our body, mainly carbon dioxide, through the airways. People can be energetic thanks to the perfect oxygen supply and waste gas discharge system - the lungs. Therefore, life lies between breathing in and breathing out.

Because the lungs are an open system, they can have external and internal troubles. "External troubles" are external pathogens, such as viruses, bacteria, molds and other infections, which can pass through the respiratory tract and reach the throat, trachea, lungs, etc. In addition, there are air pollutants, such as PM2.5. Smoking can also cause great harm to the lungs. As for "internal troubles", since the lungs are connected to the blood and lymphatic vessels throughout the body. If there are pathogens in the blood, various cytokines and toxins will cause lung damage.

Do you really know the flu?

Influenza is an acute respiratory infectious disease caused by influenza virus infection and is an important public health issue facing mankind. What impact will it have on patients?

First, if it is a common flu, a mild flu, it usually takes three to five days to recover. If it is influenza pneumonia, active treatment is needed, and some frail elderly people need to be hospitalized. If it is a severe or critical illness, hospitalization is necessary. Second, although influenza is an infectious disease of the respiratory system, it can also cause extrapulmonary complications, such as viral encephalitis, myocarditis, and Guillain-Barré syndrome, which are life-threatening.

What does the flu virus look like?

The influenza virus is spherical, with a diameter of 80 to 120 microns, and sometimes it can be filamentous. There are many small sticks and nails on its surface, which are various antigens of the virus. The nucleic acid detected by "nucleic acid monitoring" is in the core of the virus, which is the basic location of virus replication.

Influenza is very sensitive to common disinfectants such as ethanol and iodine tincture, and is sensitive to ultraviolet rays and heat. It can be inactivated by heating at 56 degrees Celsius for 30 minutes, so it is recommended to open windows, expose to the sun, and disinfect.

How does influenza spread through the respiratory tract?

Due to contact with influenza patients, latently infected people or items carrying influenza viruses, influenza viruses pass through the mouth, enter the nasopharynx and reach the throat. The virus then enters the host cells (i.e. respiratory epithelial cells) through endocytosis, where it multiplies (transcribes and replicates) in large numbers.

According to its own genes, the virus uses the substances provided by normal human cells to continuously replicate the virus, grow exponentially, and finally cause the infected cells to die. The surface of the virus is like a nail or a stick, just like a hairy chestnut, with many sharp things on the surface. If the virus touches a normal cell, it is easy to take advantage of the opportunity to enter. After the virus enters the human body, some signals will be generated in the body, and the signal molecules will summon various immune cells in the body to prepare to fight the virus. During the battle, "gunfire" will continue, and people will have fever, myalgia, back pain, sore throat, etc. In a few patients, the immune system is overactivated, and a large amount of cytokines are released, resulting in cytokine storms, causing acute respiratory failure, decreased circulatory function, and encephalopathy, dyspnea, fatigue, confusion, and nonsense. In this season, if these symptoms occur, the first thing to consider is the possibility of influenza.

How is influenza spread?

Influenza is mainly spread through droplets such as sneezing and coughing, and is transmitted through direct or indirect contact with mucous membranes such as the mouth, nose, and eyes. In addition, contact with objects contaminated by the virus can also cause infection. In certain places, such as crowded, closed or poorly ventilated rooms, influenza may also be transmitted in the form of aerosols. Children under five years old, people over 65 years old, people with underlying diseases, and pregnant women should pay special attention to protection during this season.

Clinical manifestations of influenza

The incubation period is generally one to seven days, most often two to four days, and varies from person to person.

There are two aspects of influenza symptoms: systemic symptoms and respiratory symptoms. Systemic symptoms include fever, headache, myalgia and general discomfort; respiratory symptoms include cough and sore throat, mainly dry cough. The specific manifestations vary from person to person. Some elderly people show symptoms of not wanting to eat, fatigue and apathy. For children, influenza B mainly manifests as vomiting, abdominal pain and diarrhea.

A definitive diagnosis requires monitoring of influenza virus antigen nucleic acid, etc.

Influenza is divided into mild, moderate, severe and critical types.

Generally speaking, if the patient is young and has no underlying diseases or complications, it may just be an upper respiratory tract infection, which can be relieved in 3-5 days, but the symptoms of cough and fatigue will last longer, and it will not be possible to fully recover in three to five days.

As for the moderate patients, they usually have influenza pneumonia. If they have underlying diseases, the symptoms are more obvious and they need to be hospitalized.

How to judge whether it is a serious illness? If there are elderly people and children at home, you can use an oxygen saturation meter to measure the oxygen saturation at home. The normal oxygen saturation is generally 98 or 99. If you feel uncomfortable all over one day and the oxygen saturation is 93, you should pay attention, as it may be a sign of a serious illness.

The critical condition means shortness of breath, severe breathing difficulties, and very bad overall condition.

Flu Diagnosis and Complications

Influenza should be identified, diagnosed and treated early.

If symptoms occur, you should pay attention to the epidemiological history, that is, whether you have had close contact with suspected patients without personal protection within seven days, such as contact within two meters, dining together, etc. If so, the risk of infection is relatively high.

What is the difference between influenza and the common cold?

Colds occur all year round, but influenza is often seasonal. The influenza season in southern provinces is roughly from November to March of the following year, with a small peak in the summer; in the north it is basically in winter.

To use an analogy, influenza is like a tiger, and colds are like cats, both are felines. But the "tiger" is aggressive and has great lethality, while the "cat" only meows twice at most and poses no threat.

How is the flu treated?

Principles of influenza treatment:

The first step to diagnose influenza is to isolate yourself from your family and friends. The first treatment is symptomatic treatment. If you have a headache, fever, or cough, you can take some antipyretics. When should you take antipyretics? Generally, it is when the body temperature is above 38.5 degrees. This is not necessarily the case for the elderly, because they may already feel very uncomfortable at 38 degrees. You can take cough suppressants and expectorants according to the situation. At the same time, coughing can protect the respiratory tract. Coughing can cough out viruses, mucus, and bacteria from the body, making the lungs clean.

The second is antiviral treatment. The best time to treat is within 48 hours. It can quickly improve symptoms, reduce complications, shorten hospitalization time, and reduce mortality. Severe patients should not wait, and should be given empirical anti-influenza virus treatment as soon as possible, and should not wait until the virus test results are available before treatment. Mild patients can be treated after a clear diagnosis.

How to prevent influenza?

Influenza vaccination is the most effective way to prevent influenza, especially for the elderly, children, pregnant women, infants under 6 months old, family members and caregivers. For those who have been infected, medication should be taken no later than 48 hours, such as oseltamivir and mabaloxavir.

In normal times, we should maintain good personal hygiene habits. Ventilate the room frequently. In winter, we may open the windows less often due to heating or fear of cold, but we should still open them when necessary to maintain ventilation. We should wear masks in places where we are in close contact with people, such as stations and crowded places. We should avoid contact with sick or dead animals, including wild birds, in any season. During the Spring Festival, we should wear masks when slaughtering chickens and ducks.

(Author: Ying Kejing, Deputy Director of Zhejiang Provincial Respiratory Prevention Office, and Head of Respiratory and Critical Care Medicine at Zhejiang University Run Run Shaw Hospital)

This article is based on the Thursday night school content of Zhejiang Science Popularization Federation