Avian Influenza
Introduction
Introduction to bird flu Avian influenza is a potent infectious disease caused by avian influenza virus (AIV) that is mainly prevalent in flocks. It is the abbreviation of avian influenza. It is an acute infectious disease caused by a subtype of influenza A virus (also known as avian influenza virus). It can also infect humans and is classified as a Class A infectious disease by the International Animal Diseases Bureau. Also known as true chicken or European chicken. The symptoms of human infection are mainly high fever, cough, runny nose, myalgia, etc. Most of them are accompanied by severe pneumonia. In severe cases, heart, kidney and other organ failures lead to death, and the mortality rate is very high. Usually people are infected with bird flu. The mortality rate is about 33%. The disease can be transmitted through digestive tract, respiratory tract, skin damage and conjunctiva. Inter-regional personnel and vehicles are important ways to spread the disease. basic knowledge The proportion of sickness: 0.0001% - 0.0005% (popular) Susceptible people: no specific population Mode of infection: respiratory transmission Complications: viral pneumonia Myocarditis
Cause
Avian influenza cause
Spread of the virus
Migratory birds are important broadcasters of avian flu viruses, but it is impossible to kill all the migratory birds, and the culling of migratory birds will disperse the birds that were originally gathered, making the spread of the virus more difficult to control, thus poultry and Isolation of migratory birds to avoid cross-infection is an effective means of controlling the spread of avian influenza. On many farms in China, giant nets are hung on farms that raise poultry to prevent migratory birds with viruses from infecting poultry.
In poultry, ducks and geese are infected, and their ability to resist disease is relatively high. The chance of survival after the disease is also high. However, chickens are very sensitive to the flu virus, and once infected, not only will it spread quickly, but the infected chicken will soon die. In the past, farmers used to call this phenomenon a chicken cockroach. They did not pay special attention to the reasons behind it or the mechanism of the disease. It was only after the bird flu was transmitted to the human body and died to death. At present, the main means for people to deal with avian flu is to treat the infected animals and the poultry that may be infected with the disease, such as disinfection and deep burial, so as to avoid the accumulation of viruses and affect humans.
Prevention
Avian influenza prevention
1. Strengthen the monitoring of poultry diseases. Once the bird flu epidemic is detected, the animal epidemic prevention department will immediately deal with it according to relevant regulations, and all relevant personnel in the breeding and treatment should do a good job in protection.
2. Strengthen the monitoring of close contact with poultry personnel. When flu-like symptoms appear in these personnel, an epidemiological investigation should be conducted immediately, and patient specimens should be collected and sent to designated laboratories for further identification of pathogens. Prevention.
3. Patients who are exposed to human bird flu should wear masks, gloves, and gowns. Wash hands after contact.
4. Strengthen the management of test specimens and laboratory avian influenza virus strains, strictly enforce operational practices, and prevent infection and spread of hospital infections and laboratories.
5, pay attention to food hygiene, do not drink raw water, do not eat uncooked meat and eggs and other food; wash hands frequently, develop good personal hygiene habits.
6. Drug prevention For those who are in close contact, they can try anti-influenza virus drugs or discriminate against Chinese medicine according to Chinese medicine.
Complication
Avian flu complications Complications, viral pneumonia, myocarditis
Primary viral pneumonia: more common in patients with existing cardiopulmonary disease, pulmonary lesions are mainly serous hemorrhagic bronchitis, patients often die due to heart failure or peripheral circulatory failure.
Secondary bacterial pneumonia: The most common pathogens are Streptococcus pneumoniae, Staphylococcus aureus or Haemophilus influenzae. The patient's condition is gradually worsening, or the clinical symptoms are further aggravated after a temporary improvement, coughing, coughing, and appearance. Physical signs of the lungs, X-ray found that the lungs have flaky and patchy shadows.
Myocarditis: It has been reported that influenza virus pneumonia can be complicated by myocarditis.
Symptom
Avian flu symptoms Common symptoms High fever cough, runny nose, fever, chills, muscle aches, diarrhea, transient flu-like symptoms, shock, abdominal pain, nasal congestion
1. Incubation period
No accurate reports have been made yet. It is currently estimated to be within 7 days, usually 1-3 days.
2, clinical symptoms
Acute onset of clinical symptoms, early manifestations similar to common influenza, mainly fever, body temperature mostly lasts above 39 ° C, heat range 1 to 7 days, usually 3 to 4 days, may be accompanied by salivation, nasal congestion, cough, pharynx Pain, headache and general malaise, some patients may have nausea, abdominal pain, diarrhea, watery stools and other gastrointestinal symptoms, most of the mild cases have a good prognosis. Severe patients develop rapidly, and may have various complications such as pneumonia, acute respiratory distress syndrome, pulmonary hemorrhage, pleural effusion, whole blood cell reduction, renal failure, sepsis, shock and Reye syndrome. If the body temperature continues to exceed 39 °C during treatment, it is necessary to be alert to the serious tendency. Infected patients have milder symptoms, most patients may have conjunctivitis, and a few patients have mild flu-like symptoms. H9N2 infected patients only caused transient flu symptoms, and no deaths were reported.
3, signs
Severe patients may have signs of lung consolidation.
4, complications
Most of the mild cases have a good prognosis without leaving sequelae. In some cases, the disease develops rapidly, and many complications such as severe pneumonia, acute respiratory distress syndrome, pulmonary hemorrhage, pleural effusion, pancytopenia, multiple organ failure, sepsis, shock and Reye syndrome can lead to death. .
Examine
Bird flu inspection
1. Peripheral blood
The total number of white blood cells is generally not high or decreased. In severe cases, the total number of white blood cells and lymphocytes are decreased.
2. Viral antigen and gene detection
The patient's respiratory specimens were detected by immunofluorescence (or enzyme-linked immunosorbent assay) for influenza A virus nucleoprotein antigen (NP) and avian influenza virus H subtype antigen. RT-PCR method was also used to detect avian influenza virus subtype specific H. Antigen gene.
3, virus separation
Avian influenza virus is isolated from patient respiratory specimens such as nasopharyngeal secretions, oral sputum, tracheal aspirate or airway epithelial cells.
4, serological examination
The serum titer of anti-avian influenza virus in the initial stage and recovery period is 4 times or more, which is helpful for retrospective diagnosis.
5, chest imaging examination
Chest X-ray examination of severe patients can show unilateral or bilateral pneumonia, a small number may be associated with pleural effusion.
Diagnosis
Avian influenza diagnosis and identification
Differential diagnosis
Clinical attention should be paid to the differential diagnosis of influenza, common cold, bacterial pneumonia, infectious atypical pneumonia (SARS), infectious mononucleosis, cytomegalovirus infection, chlamydia pneumonia, and mycoplasmal pneumonia.
Identification with influenza
Influenza is generally divided into three types, namely, type A, type B and type C. Types B and C are generally transmitted only in the crowd and rarely transmitted to other animals. Most of the influenza A is Avian flu and avian flu viruses are rarely ill. Avian flu is mainly transmitted among birds and can be infected with humans. Its clinical manifestations are similar to those of human influenza, but human flu symptoms are heavy and complications are numerous. There is a certain difference between ordinary flu.
