Human avian influenza
Introduction
Introduction to human avian influenza Human avian influenza is an acute respiratory infection caused by some strains of certain subtypes of avian influenza A virus. Although human avian influenza is currently only found in local areas, the World Health Organization (WHO) is considered in view of the general lack of immunity of human avian influenza virus, the high mortality rate of human infection with H5N1 avian influenza virus, and possible viral mutations. The disease is considered to be one of the most potentially threatening diseases for humans. basic knowledge The proportion of illness: 0.056% Susceptible people: no special people Mode of infection: respiratory infection Complications: pneumonia
Cause
Causes of human avian influenza
Spread of the virus
It is mainly chickens, ducks, geese and other poultry that are suffering from bird flu or carrying avian influenza virus. Wild birds play an important role in the natural spread of avian flu. There is no definitive evidence of communication between people. Transmission through the respiratory tract can also be infected by close contact with infected poultry secretions and excreta, contaminated items and water, and direct exposure to viral strains can also be infected.
Immunocompromised
It is generally believed that humans are not susceptible to the avian flu virus. Although it can be infected at any age, among the cases of H5N1 infection that have been found, the proportion of children under the age of 13 is higher and the condition is heavier.
envirnmental factor
Poultry farmers and their families living in the same place, those who have been to poultry breeding, sale and slaughter within one week before the onset, laboratory workers exposed to avian influenza virus infection materials, and close contact with avian influenza patients Personnel are at high risk.
Prevention
Human avian influenza prevention
1. Minimize the unnecessary contact between people, especially children and poultry and birds, especially with sick and dead birds.
2. Those who must contact because of professional relationships should wear masks and overalls during work.
3. Strengthen the monitoring of poultry diseases. Once the animal epidemic prevention department finds a suspected bird flu epidemic, it should immediately notify the local disease prevention and control agency to guide the occupational exposure personnel to do a good job in protection.
4. Strengthen monitoring of close contact with poultry personnel. Those who have close contact with poultry or human avian influenza patients should immediately conduct an epidemiological investigation if they have flu-like symptoms, collect patient specimens and send them to designated laboratories for further identification of pathogens, and take appropriate preventive measures. . Conditional patients can take oral neuraminidase inhibitors within 48 hours.
5. Strictly regulate the control measures for nosocomial infections of medical units for human influenza patients. Patients who are exposed to human bird flu should wear masks, gloves, goggles, and gowns. Wash hands after contact.
6. Strengthen the management of test specimens and laboratory avian influenza virus strains, strictly implement operational specifications, and prevent infection and spread of laboratories.
7, 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.
8, can use traditional Chinese medicine methods to distinguish between evidence. The basic principles of using traditional Chinese medicine to prevent this disease: Yiqi Jiedu, Xuanfei and dampness. Applicable to high-risk groups, should be used under the guidance of a doctor.
Complication
Human avian influenza complications Complications pneumonia
The disease can be complicated by pneumonia.
The symptoms of pneumonia are: chills, high fever, cough, cough, chest pain, difficulty breathing.
Symptom
Human avian influenza symptoms Common symptoms Fever, sore throat, muscle soreness, pulsating headache, sneezing, runny nose
Incubation period
According to the investigation of H5N1 subtype infection cases, the incubation period is generally 1 to 7 days, usually 2-4 days.
Clinical symptoms
Different subtypes of avian influenza virus can cause different clinical symptoms after infecting humans. Patients infected with H9N2 subtype usually have only mild symptoms of upper respiratory tract infection, and some patients do not even have any symptoms; patients infected with H7N7 subtype are mainly conjunctivitis; severe patients are generally infected with H5N1 subtype virus. The patient developed an acute onset and his early performance was similar to that of a common influenza. Mainly for fever, body temperature mostly lasts above 39 °C, may be associated with salivation, nasal congestion, cough, sore throat, headache, muscle aches and general malaise. Some patients may have gastrointestinal symptoms such as nausea, abdominal pain, diarrhea, and watery stools.
In severe cases, high fever can occur, and the disease develops rapidly. Almost all patients have clinically significant pneumonia, which can cause acute lung injury, acute respiratory distress syndrome (ARDS), pulmonary hemorrhage, pleural effusion, whole blood cell reduction, and more. Organ dysfunction, shock and Reye syndrome and many other complications. It can be followed by bacterial infection and sepsis.
Sign
Severe patients may have signs of lung consolidation.
Examine
Inspection of human avian influenza
Auxiliary inspection
Pulmonary infiltration can occur in people infected with H5N1 subtype virus. Chest imaging can be seen as a lamella in the lungs. The lesions in the lungs of severe patients progressed rapidly, showing large-scale ground glass-like shadows and lung consolidation images. The late stage of the lesions was diffuse solid shadows of both lungs, which could be combined with pleural effusion.
Laboratory inspection
Peripheral blood
The total number of white blood cells is generally not high or low. In severe cases, the total number of white blood cells and lymphocytes decreased, and platelets decreased.
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) or matrix protein (M1) and avian influenza virus H subtype antigen. The avian influenza virus subtype-specific H antigen gene can also be detected by RT-PCR.
Virus isolation
Avian influenza virus is isolated from a patient's respiratory specimens (eg, nasopharyngeal secretions, oral sputum, tracheal aspirate, or airway epithelial cells).
Serological examination
The antibody titer of the two serum avian influenza virus subtype strains increased by 4 times or more in the early stage of the disease and during the recovery period, which is helpful for retrospective diagnosis.
Diagnosis
Diagnosis and diagnosis of human avian influenza
Diagnosis of human avian influenza can be made based on epidemiological exposure history, clinical manifestations, and laboratory findings.
Epidemiological exposure history
1. I have been to the epidemic point within 1 week before the onset of the disease.
2. History of exposure to sick and dead birds.
3. Close contact with infected birds or their secretions, excretions, etc.
4. Close contact with avian influenza patients.
5. The laboratory is engaged in research on avian influenza virus.
Diagnostic criteria
1. Medical observation cases: There is a history of epidemiological exposure, and influenza-like clinical manifestations appear within 1 week.
For those diagnosed as medical observation cases, the medical institution shall promptly report to the local disease prevention and control institution and conduct a 7-day medical observation.
2, suspected cases: epidemiological exposure history and clinical manifestations, respiratory secretions or related tissue specimens of influenza A virus M1 or NP antigen detection positive or the nucleic acid detection of them positive.
3. Clinically diagnosed cases: diagnosed as suspected cases, but no further clinical test specimens or laboratory test evidence can be obtained, but those with a history of joint contact are diagnosed as confirmed cases and can exclude other diagnoses.
4, confirmed cases: epidemiological exposure history and clinical manifestations, from the patient's respiratory secretions specimens or related tissue samples to isolate specific viruses, or other methods, avian influenza virus subtype specific antigen or nucleic acid test positive, or disease The antibody titer of the double serum avian influenza virus subtype strain increased by 4 times or more in the initial and recovery period.
Differential diagnosis
Clinical attention should be paid to influenza, common cold, bacterial pneumonia, infectious atypical pneumonia (SARS), infectious mononucleosis, cytomegalovirus infection, chlamydial pneumonia, mycoplasma pneumonia, legionellosis, pneumonia epidemiology Differential diagnosis such as hemorrhagic fever. Differential diagnosis relies mainly on pathogenic examination.
If the epidemiological history is unknown, the specific virus is isolated from the patient's respiratory secretions or related tissue specimens based on clinical manifestations, auxiliary examinations, and laboratory tests, or other methods, avian influenza virus subtype-specific antigens. Or the nucleic acid test is positive, or the antibody titer of the double serum avian influenza virus subtype strain is increased by 4 times or more in the initial stage and the recovery period, and the confirmed case can be diagnosed.
