The cause of avian influenza How to treat and prevent avian influenza？

　　Avian influenza is an infectious disease caused by avian influenza virus. Its appearance and development are related to many reasons. Do you know what the causes of avian influenza are? Today, Xiaobian will introduce how to treat and prevent bird flu. Come and have a look!

　　catalogue

　　1. What is bird flu? 2. The cause of bird flu.

　　3. Symptoms and manifestations of avian influenza 4. Inspection and identification of avian influenza

　　5. How to treat bird flu 6. How to prevent bird flu correctly

　　7, bird flu diet and health care 8, bird flu patients can eat pork?

　　9. remedies for preventing bird flu 10. coup for daily prevention of bird flu

　　11. Can drinking prevent bird flu?

　　What is bird flu?

　　Avian influenza is a human disease caused by avian influenza virus. Avian influenza virus belongs to influenza A virus. According to the pathogenicity of avian influenza virus to chickens and turkeys, it is divided into three levels: high, medium, low/non-pathogenicity. Due to the characteristics of hemagglutinin structure of avian influenza virus, it generally infects poultry. When the virus is genetically rearranged during replication, the structure changes and the ability to infect people is acquired, it may cause human infection with avian influenza. Up to now, it has been found that the subtypes of avian influenza virus that can directly infect humans are H5N1, H7N1, H9N2, H7N9, H7N9 and H7N9. Among them, the highly pathogenic H5N1 subtype and the new avian influenza H7N9 subtype first discovered in March, 2013 are particularly interesting, which not only caused human casualties, but also dealt a heavy blow to the poultry industry.

　　Discovery history and epidemiology

　　It was isolated from plague chickens in 1878. In 1901, it was called "filter factor" or chicken plague virus (FPV). Later, it was found that Newcastle disease virus (NDV) can also cause chicken plague-like diseases in poultry, which is commonly known as "chicken plague" in China.

　　In order to distinguish the two, the former is called true chicken plague or European chicken plague virus, and the latter is called pseudo chicken plague or Asian chicken plague virus. In 1955, FPV was identified as a member of influenza A virus according to the antigenic characteristics of virus granular nucleoprotein. Most of them don’t cause fowl plague, even in a state of silent infection or healthy carrying. For example, H7N9 avian influenza virus newly discovered in China in 2013 basically doesn’t cause disease among birds.

　　H5N1 subtype was first discovered in Hong Kong in 1997, which can directly infect humans. Up to March 2013, 622 cases of human infection with highly pathogenic H5N1 avian influenza were reported in the world, of which 371 cases died. The cases were distributed in 15 countries, among which 45 cases were found in China and 30 cases died. Most cases of human infection with H5N1 avian influenza are young people and children. In March 2013, a case of human infection with H7N9 avian influenza was first discovered in China. By May 1, 2013, 10 provinces (cities) including Shanghai, Anhui, Jiangsu, Zhejiang, Beijing, Henan, Shandong, Jiangxi, Hunan and Fujian had reported 127 confirmed cases, including 26 deaths. The majority of cases are elderly people, with more men than women. At present, it is found that the source of human infection with avian influenza is birds carrying the virus. The route of transmission still needs to be clear. It is believed that the main route of human infection with H5N1 subtype avian influenza is close contact with dead birds, and high-risk behaviors include slaughtering, plucking and processing infected birds.

　　In a few cases, when children play in areas where free-range poultry frequently appear, exposure to poultry feces is also considered as a source of infection. At present, most evidences show that there is bird-to-human transmission, there may be environmental (environment polluted by poultry excrement)-human transmission, and a few non-sustainable human transmission of H5N1. At present, it is believed that patients with H7N9 avian influenza are infected by direct contact with articles and environment polluted by poultry or their excreta. Cases of human infection with H7N9 avian influenza are still sporadic. Although there have been some cases of family aggregation, at present, the virus has not been found to have the ability of continuous human-to-human transmission.

　　The World Health Organization believes that the best way to prevent bird flu is to avoid contact with poultry. How to avoid contact with poultry when you need to buy them in the market. Wash your hands thoroughly with soap or hand sanitizer after handling live chickens, refrigerating and thawing raw chickens or eggs. All kinds of kitchen tools that have come into contact with poultry should also be cleaned and disinfected. Uncooked poultry should be covered and put into the freezer of the refrigerator, and stored separately from cooked food. The shells of poultry eggs should also be thoroughly cleaned before cooking.

　　The cause of avian influenza

　　Under normal circumstances, bird flu will not be transmitted to people. Because humans do not have the specific receptor of avian influenza virus, that is, avian influenza virus can not be recognized and combined by * cells. On the other hand, the gene combination of avian influenza virus does not contain the gene fragment of human influenza virus. At present, some highly pathogenic avian influenza viruses have infected people, indicating that these viruses have undergone certain mutations, but this mutation does not have the ability to spread from person to person.

　　A pathogen

　　Avian influenza is caused by avian influenza A virus. H7N9 is a subtype of avian influenza. In the past, it was only found among birds, and no human infection was found. Influenza viruses have two surface antigens, hemagglutinin and neuraminidase. According to different antigenicity, influenza viruses can be divided into three types: A, B and C, A can be found in humans, poultry, pigs, horses and other mammals, and B, B and C are generally only found in humans.

　　H and N can be further subdivided. H can be divided into H1 ~ H15 and N can be divided into N1 ~ N9. Different H and N can form subtypes with different antigenicity and pathogenicity. There are 145 subtypes of influenza A virus, among which H1 ~ H3 are the main types that can cause human influenza, and H1N1, H2N2 and H3N2 have caused influenza pandemics in humans. The natural hosts of most other subtypes are birds, pigs, horses and other animals.

　　Second source of infection

　　The main sources of infection of avian influenza are chickens, ducks and geese who suffer from avian influenza or carry avian influenza virus, but it is not excluded that other poultry, mammals, pigs and horses may become the sources of infection. The international trade of poultry and the infection of migratory wild birds with avian influenza virus may be the important reasons for the long-distance transmission across borders and regions. Recently, Germany reported that H5N1 avian influenza virus was detected in a dead cat.

　　Iii. route of infection

　　Experiments show that avian infection can be caused by aerosol, intranasal, sinus, trachea, mouth, conjunctiva, muscle, abdominal cavity, vein, cloaca and brain inoculation. Under natural conditions, the route of transmission is still completely clear, and it is generally believed that transmission is achieved through multiple channels.

　　1, spread by air droplets

　　Secretions or excretions of sick birds or avian influenza virus birds are spread by airborne droplets.

　　2, spread through water sources

　　Up to now, it has been confirmed that influenza virus can be isolated from cloaca of flying ducks, feces of waterfowl and lake water. It shows that influenza virus can spread in water by taking a mouthful of feces.

　　3. Close contact

　　There are different views on existence. Some people think that close contact is necessary for communication, while others think that it is not necessary. For example, it has been reported that contact transmission has taken place among flat turkeys, but caged turkeys that are more than one meter above the ground in the same room are not spread. Some facts show that although the chickens are close together and the breeders have not taken measures to prevent the spread, the infection has not spread to all the chickens.

　　4. Vertical transmission

　　It has been reported that 7000 fertilized eggs and 1100 1-day-old turkeys were imported together, resulting in an influenza outbreak in 8l00 turkeys. Because infected eggs are used for hatching, species turkeys are infected, which is common in North America, which is confirmed by isolating viruses from eggs laid by infected turkeys. Therefore, the possibility of vertical transmission exists.

　　Epidemiological investigation proves that avian influenza is horizontal transmission. Cutting off its transmission route can control the epidemic spread of the disease. The virus is sensitive to high temperature, and it can be inactivated in 2 minutes to 10 minutes at 60-70℃. Cooked poultry meat, eggs and poultry products sold in the market can be safely eaten. There’s no need to panic.

　　Symptoms and manifestations of avian influenza

　　According to the investigation results of human cases infected with H7N9 and H5N1 avian influenza, the incubation period is generally within 7 days.

　　The patient’s initial symptoms are flu-like, including fever and cough, which may be accompanied by headache, muscle aches and general malaise, as well as runny nose, stuffy nose and sore throat.

　　Some patients have chest tightness and dyspnea when their lung lesions are serious or their condition develops rapidly. Respiratory symptoms appear earlier, usually within 1 week after onset, and last for a long time. Some patients still have severe cough and expectoration after treatment for 1 month.

　　Chest tightness, shortness of breath and dyspnea in the early stage of the disease often suggest that lung lesions progress rapidly and will rapidly develop into severe hypoxia and respiratory failure.

　　The condition of severe patients develops rapidly, and severe pneumonia occurs in 5 ~ 7 days. Most of them have a temperature above 39℃, and they have difficulty breathing, which may be accompanied by hemoptysis and phlegm. It can rapidly progress to acute respiratory distress syndrome, sepsis and septic shock, and some patients may have mediastinal emphysema and pleural effusion.

　　A considerable proportion of severe patients are complicated with injuries or failures of other systems or organs at the same time, such as heart failure caused by myocardial injury. Some patients also have digestive system symptoms such as gastrointestinal bleeding and emergency ulcer, and some severe patients have coma and disturbance of consciousness.

　　The white blood cell level of most people infected with avian influenza is lower than normal, and the lymphocyte level is not high or even decreased. If the platelet level decreases, it is necessary to consider whether there is disseminated intravascular coagulation caused by severe infection, and it should be comprehensively differentiated by coagulation analysis and fibrinogen level.

　　Blood biochemical tests showed that creatine kinase, lactate dehydrogenase, aspartate aminotransferase and alanine aminotransferase increased, C-reactive protein increased and myoglobin increased.

　　Imaging examination showed that there were flaky shadows in the lungs of patients with pneumonia. The lesions of severe patients progress rapidly, showing multiple ground glass shadows and consolidation images of both lungs, which may be combined with a small amount of pleural effusion. When ARDS occurs, the lesions are widely distributed.

　　The most reliable is still pathogen detection. Before antiviral treatment, qualified medical units should collect respiratory tract samples for inspection as much as possible (such as nasopharyngeal secretions, mouthwash, tracheal aspirate or respiratory epithelial cells) for virus nucleic acid detection (real-time fluorescence PCR detection) and virus isolation.

　　In addition to avian influenza virus infection, human patients infected with avian influenza often have bacterial infection or secondary infection at an early stage, and fungal infection can also be combined after a long time or a large dose of antibiotics and improper use of glucocorticoid.

　　Therefore, sputum culture and respiratory aspirate culture should be carried out for many times in clinic to check the types of bacteria and/or fungi and their sensitive or drug-resistant types, so as to rationally select antibiotics in clinic and guide clinical treatment.

　　What are the symptoms of avian influenza?

　　After people are infected with highly pathogenic avian influenza, the onset is very urgent, and the early manifestations are similar to ordinary influenza. The main manifestation is fever, the body temperature is above 39℃ for 1 ~ 7 days, usually 3 ~ 4 days, which may be accompanied by runny nose, stuffy nose, cough, sore throat, headache and general malaise.

　　Some patients may have digestive tract symptoms such as nausea, abdominal pain, diarrhea and watery stools. In addition to the above manifestations, severe patients infected with highly pathogenic avian influenza may also have pneumonia, respiratory distress and other manifestations, and even lead to death.

　　[Common symptoms]

　　1, mild to severe respiratory symptoms, including coughing, sneezing and a lot of tears.

　　2, head and face edema, nervous disorder and diarrhea.

　　Any of these symptoms may appear alone or in different combinations. Sometimes the disease breaks out quickly, and chickens are found dead when there are no obvious symptoms.

　　[diagnosis]

　　1, epidemiology

　　Avian influenza virus has a wide range of hosts, such as chickens, turkeys, ducks, geese, quails and pheasants, as well as wild birds, waterfowl and seabirds. Birds of all ages can be infected. Among them, chickens and turkeys are the most harmful after being infected with avian influenza virus, and more viruses are isolated from ducks than other poultry.

　　Poisonous birds or waterfowl often become the source of infection, causing a large number of diseases and deaths of poultry. Avian influenza virus is mainly transmitted through direct contact and indirect contact with infected birds, including equipment in contact with infected birds.

　　2. Pathological changes

　　The pathological changes of avian influenza vary with the virulence of the infected strains, the duration of the disease and the species of birds. The main manifestations are head swelling, fleshy beard, crown bleeding, subcutaneous bleeding of calf and toe, glandular stomach nipple bleeding and salpingitis.

　　3. Etiological diagnosis

　　Virus isolation needs to be completed by the national laboratory.

　　In daily life, we should pay attention to develop good personal hygiene habits, strengthen indoor air circulation, and open the window for half an hour once or twice a day. When eating poultry meat, it should be cooked thoroughly. When eating eggs, the eggshells should be washed with running water, and should be cooked and heated fully. Do not eat raw or half-baked eggs.

　　Have enough sleep and rest, have a balanced diet, and pay attention to eating more foods rich in vitamin C and other immune-enhancing foods. Regular physical exercise to increase the body’s resistance to viruses.

　　Inspection and Identification of Avian Influenza

　　1, immunofluorescence or enzyme-linked immunosorbent assay detection

　　Virus antigen and gene detection The respiratory tract samples of patients were detected by immunofluorescence or enzyme-linked immunosorbent assay (ELISA) for nucleoprotein antigen NP of influenza A virus and subtype H antigen of avian influenza virus.

　　2. Serological examination

　　The titer of anti-avian influenza virus antibody in the initial stage and recovery stage of the disease increased by 4 times or more, which is helpful for retrospective diagnosis.

　　3, chest imaging examination

　　Chest x-ray examination of severe patients can show unilateral or bilateral pneumonia, and a few patients can be accompanied by pleural effusion.

　　4, blood routine examination

　　The total number of white blood cells in peripheral blood is generally not high or low. The total number of white blood cells and lymphocytes decreased in severe patients.

　　5, RT-PCR detection.

　　Detection of subtype-specific H antigen gene of avian influenza virus by RT-PCR.

　　6. Virus isolation

　　Avian influenza virus was isolated from respiratory specimens of patients such as nasopharyngeal secretions, mouthwash, tracheal aspirate or respiratory epithelial cells.　　[identification]

　　1. Differentiate from influenza

　　Influenza is generally divided into three types, namely type A, type B and type C.. Influenza B and C generally only spread among people and rarely spread to other animals. Influenza A is mostly avian influenza, and avian influenza virus rarely causes people to get sick.

　　Avian influenza mainly spreads among birds and occasionally infects people. Its clinical manifestations are similar to human influenza, but human avian influenza has serious symptoms and many complications, which is different from ordinary influenza.

　　2. Bacterial pneumonia

　　There are mainly infectious and physical and chemical diseases such as radiation, poisonous gas, drugs and allergic pneumonia, etc. Most of the clinical manifestations are infectious pneumonia caused by bacteria, viruses, chlamydia, mycoplasma, rickettsia, fungi and parasites, among which bacteria are the most common.

　　3. Chlamydia pneumonia

　　Chlamydia pneumoniae has the same genus-specific antigen as psittacosis and Chlamydia trachomatis, but the serological characteristics of other specific antigens are different. Usually, DNA hybridization test and restriction endonucleases analysis confirm that it is the third chlamydia different from Chlamydia trachomatis and Chlamydia psittaci.

　　Don’t underestimate a bad cold. The symptoms of bird flu are similar to those of other influenza, such as fever, headache, cough and sore throat. In some cases, it can cause complications and lead to the death of patients. Therefore, if you have respiratory symptoms such as fever, headache, stuffy nose, cough and general malaise, you should wear a mask and go to the hospital as soon as possible, and be sure to tell the doctor whether you have been to the bird flu epidemic area before the onset, whether you have been in contact with sick birds, and treat and use drugs under the guidance of a doctor.

　　How to treat avian influenza?

　　The treatment strategy of human infection with avian influenza is mainly to give symptomatic maintenance, anti-infection, ensure oxygen supply to tissues and maintain organ function under appropriate isolation conditions. Symptomatic maintenance mainly includes bed rest, dynamic monitoring of vital signs and physical or drug cooling. Anti-infection therapy includes antiviral therapy (such as oseltamivir, zanamivir, palamivir, etc.) and anti-bacteria, viruses and fungi, but it emphasizes that the timing of clinical treatment should be "early, fast and accurate". In particular, antiviral drugs should be taken from respiratory tract samples before use, and should be used within 48 hours of onset as far as possible. For cases that need antiviral drugs clinically, they can also be used after 48 hours of onset.

　　Ensuring tissue oxygenation is the core to maintain the normal function of important organs in severe and critically ill patients, which can be carried out by selecting nasal tube, mouth/nose mask, noninvasive ventilation and invasive ventilation. Specific treatment methods should be carried out under the guidance of professional doctors to avoid drug abuse and improper operation, resulting in drug resistance and delaying illness.

　　Influenza virus is a big family, which includes human A, B and C and animal A and C. Only influenza A virus can cause the spread between people and birds. The so-called H7N9 avian influenza virus is an influenza virus whose surface consists of red blood cell hemagglutinin and neuroamino acid enzyme H7 and N9, and it is mainly prevalent in poultry and animals. Once patients are suspected of avian influenza virus infection, they should be hospitalized immediately for observation and treatment to prevent the disease from getting worse, and at the same time report the epidemic situation to prevent the spread of the epidemic. At present, there is no specific treatment for avian influenza. From the two treatment directions of Chinese medicine and western medicine, it can be divided into the following treatment methods.

　　Western medicine

　　1. Symptomatic treatment

　　1.1 Antipyretic drugs, drugs for relieving nasal congestion, drugs for relieving cough and eliminating phlegm can be used.

　　1.2 Children should avoid using aspirin or drugs containing aspirin and other salicylic acid preparations to avoid causing Reye syndrome in children.

　　2, isolation treatment

　　In order to prevent the virus from spreading further and mutating, the suspected and confirmed patients should be treated in isolation.