20 15 people infected with H7N9 avian influenza epidemic.

Diagnosis and treatment scheme of human infection with H7N9 avian influenza (version 20 14)

Human infection with H7N9 avian influenza is an acute respiratory infectious disease caused by H7N9 avian influenza virus. Severe pneumonia cases can often be complicated with acute respiratory distress syndrome, septic shock and even multiple organ failure. Early detection, early reporting, early diagnosis and early treatment, strengthening the treatment of severe cases, and paying equal attention to Chinese and western medicine are the keys to effective prevention and control, improving the cure rate and reducing the mortality rate.

I. Etiology

Avian influenza virus belongs to orthomyxoviridae influenza A virus. Influenza A virus particles are polymorphic, with a spherical diameter of 80 ~ 120 nm and an envelope. The genome is a segmented single negative strand RNA. According to the antigenicity of hemagglutinin (H) and neuraminidase (N), it can be divided into 16 H subtype (H 1 ~ H 16) and 9 N subtype (N 1 ~ N9). Avian influenza A virus can infect not only birds, but also humans, pigs, horses, minks and marine mammals. Avian influenza virus subtypes that can infect humans are H5N 1, H9N2, H7N9, H7N2, H7N9, etc. This time it is H7N9 avian influenza virus. The virus is a new recombinant virus. The gene encoding HA comes from H7N3, and the gene encoding NA comes from H9N2 avian influenza virus.

Avian influenza virus is generally sensitive to heat and has strong resistance to low temperature. Heating at 65℃ for 30 minutes or boiling at (100℃) for more than 2 minutes can inactivate it. The virus can survive 1 week at low temperature and 1 year in water at 4℃ or in the presence of glycerol.

Second, epidemiology.

(1) source of infection. H7N9 avian influenza virus has been detected and isolated from poultry, their secretions or excretions and environmental samples of live poultry market, which is highly homologous to human infection with H7N9 avian influenza virus. The source of infection may be birds carrying H7N9 avian influenza virus. Most of them are sporadic cases, and some families gather to get sick, but there is no evidence of continuous interpersonal transmission.

(2) means of communication. The infection can be acquired through respiratory transmission or close contact with the secretions or excreta of infected birds; Or spread to people through contact with the environment polluted by the virus; Limited discontinuous interpersonal communication is not excluded.

(3) high-risk groups. People who had contact with poultry or went to live poultry market within 1 week before onset, especially the elderly.

Three. Pathogenesis and pathology

H7N9 avian influenza virus can simultaneously bind sialic acid α-2,3 receptor (avian influenza virus receptor) and sialic acid α-2,6 receptor (human influenza virus receptor). Compared with H5N 1 avian influenza virus, H7N9 avian influenza virus is more likely to bind with human upper respiratory epithelial cells (mainly sialic acid α-2,6 receptors) and infect human lower respiratory epithelial cells (mainly sialic acid α-2,3 receptors) than seasonal influenza virus. After being infected with H7N9 avian influenza virus, it can induce cytokine storm, lead to systemic inflammatory reaction, and may lead to ARDS, shock and multiple organ failure. Individual severe cases of lower respiratory virus can continue to be positive for more than 3 weeks.

Fourth, clinical manifestations.

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

(1) Symptoms, signs and clinical features. Patients usually show flu-like symptoms, such as fever, cough and scanty phlegm, which may be accompanied by headache, muscle aches, diarrhea and other systemic symptoms. Severe patients developed rapidly, and severe pneumonia appeared 3 ~ 7 days after onset. Most of them have a body temperature above 39℃, and have difficulty breathing, which may be accompanied by hemoptysis and phlegm. It often progresses rapidly to acute respiratory distress syndrome, sepsis, septic shock, and even multiple organ dysfunction, and some patients may have pleural effusion and other manifestations.

(2) Laboratory inspection.

1. Blood routine. The total number of white blood cells is generally not high or low. Most severe patients have decreased white blood cells and lymphocytes, and may have thrombocytopenia.

2. Blood biochemical examination. Creatine kinase, lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, C-reactive protein and myoglobin all increased.

3. Etiology and related detection. Before antiviral treatment, respiratory tract samples must be collected for inspection (such as nasopharyngeal secretions, oral gargle, respiratory tract secretions and tracheal aspirates), and the positive rate of deep tracheal expectoration or tracheal aspirates is higher than that of upper respiratory tract samples. Medical institutions with pathogen detection conditions should be tested as soon as possible, and medical institutions without pathogen detection conditions should be sampled and sent to designated institutions for testing as soon as possible.

(1) nucleic acid detection. Real-time PCR (or ordinary RT-PCR) was used to detect the nucleic acid of H7N9 avian influenza virus in respiratory tract samples of suspicious patients, and nucleic acid detection should be the first choice for early identification of human cases infected with H7N9 avian influenza virus. In severe cases, nucleic acid detection of respiratory secretions should be carried out regularly until it turns negative. Those with artificial airway have priority to collect the aspirate (ETA) in the airway.

(2) Detection of influenza A virus antigen. Rapid detection of influenza A virus antigen in respiratory tract samples was positive. It is only suitable for medical institutions without nucleic acid detection conditions as a preliminary screening experiment.

(3) Virus isolation. H7N9 avian influenza virus was isolated from respiratory tract samples of patients.

(4) Dynamic detection of the specific antibody level of H7N9 avian influenza virus in acute phase and recovery phase increased by 4 times or more.

(3) Chest imaging examination. There are patchy shadows in the lungs of patients with pneumonia. The lesions of severe patients progress rapidly, often 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.

(4) Prognosis. Severe patients infected with H7N9 avian influenza have poor prognosis. Factors affecting the prognosis may include the patient's age, basic diseases and complications.

Verb (abbreviation of verb) diagnosis and differential diagnosis

(1) diagnosis. According to the epidemiological contact history, clinical manifestations and laboratory test results, people can be diagnosed as infected with H7N9 avian influenza. In the case of unknown epidemiological history, according to the clinical manifestations, auxiliary examination and laboratory test results, especially the H7N9 avian influenza virus was isolated from the patient's respiratory secretions, or the H7N9 avian influenza virus nucleic acid was positive, or the level of H7N9 avian influenza virus-specific antibody in two serum samples was dynamically increased by more than 4 times, which can be used as a diagnostic basis for human infection with H7N9 avian influenza.

1. Epidemiological history. Contact with poultry and their secretions and excreta before onset 1 week, or go to live poultry market, or have epidemiological contact with human cases infected with H7N9 avian influenza.

2. Diagnostic criteria.

(1) Suspected case: it conforms to the above clinical manifestations, is positive for influenza A virus antigen, or has an epidemiological history.

(2) Confirmed cases: they meet the above clinical manifestations or have a history of epidemiological contact, and the H7N9 avian influenza virus or H7N9 avian influenza virus nucleic acid isolated from respiratory secretions samples is positive, or the level of H7N9 avian influenza virus-specific antibody in two serum samples is increased by 4 times or more.

(3) Severe cases:

Meet any of the following criteria, that is, the diagnosis of severe cases:

1.x-ray chest film showed that it was a multi-leaf lesion or the lesion progressed within 48 hours >: 50%;

2. dyspnea, respiratory frequency >; 24 times/minute;

3. Severe hypoxemia, when the oxygen flow rate is 3 ~ 5 liters/minute, the spo 2 of the patient is less than 92%;

4. Shock, ARDS or MODS (multiple organ dysfunction syndrome) occurs.

Risk factors that can easily develop into serious diseases include:

1. Age > 60 years old;

2. Complicated with serious basic diseases or special clinical conditions, such as heart or lung basic diseases, hypertension, diabetes, obesity, tumor, immunosuppression, pregnant women, etc. ;

3. Persistent high fever (T & GT39℃) for 3 days or more after onset;

4. Lymphocyte count continues to decrease;

5.CRP, LDH and CK increased continuously;

6. Chest imaging suggests pneumonia.

Patients with any of the above conditions may progress to severe illness or death, which should be paid great attention to.

(2) Differential diagnosis. Attention should be paid to the differential diagnosis between human infection with highly pathogenic H5N 1 avian influenza and other avian influenza, seasonal influenza (including influenza A H 1N 1), bacterial pneumonia, infectious atypical pneumonia (SARS), Middle East respiratory syndrome (MERS), adenovirus pneumonia, chlamydia pneumonia, mycoplasma pneumonia and other diseases. Differential diagnosis mainly depends on pathogenic examination.

Sixth, treatment.

(1) isolation treatment. Suspected cases and confirmed cases should be treated in isolation as soon as possible.

(2) symptomatic treatment. Oxygen can be absorbed. According to the degree of hypoxia, nasal catheter, open mask and oxygen storage mask can be used for oxygen therapy. People with high fever can carry out physical cooling or apply antipyretic drugs. Patients with severe cough and expectoration can be given compound licorice tablets, ambroxol hydrochloride, acetylcysteine, codeine and other cough-relieving and expectorant drugs.

(3) antiviral therapy. Antiinfluenza drugs should be used as soon as possible.

1. Principles for the use of antiviral drugs.

(1) respiratory specimens should be collected before using antiviral drugs.

(2) Antiviral drugs should be used within 48 hours of onset.

Focus on the following groups:

① Cases of human infection with H7N9 avian influenza;

② Influenza-like cases with positive detection of influenza A virus antigen;

③ For influenza-like cases with negative rapid detection or unconditional detection of influenza A virus antigen, antiviral drugs should also be used under the following circumstances:

A. People (including medical staff) who have a close contact history with suspected or confirmed cases have flu-like symptoms;

B. clustering influenza-like cases;

C. Influenza-like cases that have been exposed to poultry within 1 week;

D. Influenza-like cases with chronic heart and lung diseases, advanced age and pregnancy;

E. Influenza-like cases with rapid progress and clinical need for antiviral drugs;

F. Other cases of pneumonia with unknown causes.

(3) For cases that need antiviral drugs clinically, they should be used even if the onset is more than 48 hours.

2. Neuraminidase inhibitors:

(1) oseltamivir: the adult dose is 75mg, twice a day, and the course of treatment is 5-7 days. The dosage of severe cases can be doubled and the course of treatment can be more than doubled. 1 year-old and above should be given according to their body weight: those who weigh less than 15Kg twice a day, 30mg body weight 15 ~ 23 kg each time, 45mg twice a day; Weight 23 ~ 40 kg, 60 mg twice a day; Those who weigh more than 40Kg are given 75mg twice a day. For children who have difficulty swallowing capsules, oseltamivir suspension can be used.

(2) Paramivir: Paramivir sodium chloride injection can be used for patients who are seriously ill or unable to take orally. The adult dose is 300 ~ 600 mg, and it is given intravenously/kloc-0 once a day for 1 ~ 5 days. The course of treatment for severe cases can be extended appropriately. Clinical application data is limited, and adverse reactions should be closely observed.

(3) Zanamivir: Usage for adults and adolescents over 7 years old: twice a day with an interval of 12 hours; Every time 10mg (inhaled twice).

3. Ion channel M2 blocker: Monitoring data show that all H7N9 avian influenza viruses are resistant to amantadine and rimantadine, so it is not recommended to use them.

(4) TCM treatment based on syndrome differentiation.

1. The epidemic drug invaded the lung, and the lung failed to declare the disease (the suspected case or the confirmed case was mild).

Symptoms: fever, cough, scanty phlegm, headache, muscle and joint pain. The tongue is red with thin fur, and the pulse number is slippery. The tongue is red with thin fur and smooth pulse.

Treatment: clearing away heat and toxic materials, dispersing lung and relieving cough.

Reference prescription and dosage: Yinqiao powder combined with Baihu decoction.

Honeysuckle 30g, forsythia suspensa 15g, stir-fried almond 15g, gypsum 30g.

Anemarrhena rhizome 10g, mulberry leaf 15g, reed rhizome 30g, Artemisia annua 15g.

Scutellaria baicalensis Georgi 15g, Glycyrrhiza uralensis Fisch 6g.

Decoct with water, 0/~ 2 doses per day, and take orally every 4 ~ 6 hours.

Addition and subtraction: severe cough plus loquat leaves and Fritillaria thunbergii.

Chinese patent medicine: You can choose Shufeng Jiedu Capsule, Lianhua Qingwen Capsule, Jinlian Qingre Effervescent Tablet and other drugs with the functions of clearing away heat and toxic materials, dispersing lung qi and relieving cough.

Traditional Chinese medicine injections: Tanreqing injection, Xiyanping injection, Reduning injection, Xuebijing injection and Shenmai injection.

2. The epidemic situation is choking lung, confinement and detachment syndrome (high fever, acute respiratory distress syndrome, septic shock, etc.). ).

Symptoms: high fever, cough, difficulty in expectoration, shortness of breath, shortness of breath, hemoptysis, or coughing up pink foamy sputum, accompanied by discomfort at four ends, limb paralysis, irritability and even delirium. The tongue is dark red, and the pulse is thin or slightly heartbroken.

Treatment: detoxifying and purging lung, benefiting qi and dispersing stagnation.

Reference prescription and dosage: Baixuan Chengqi decoction combined with Shenshu decoction.

Raw rhubarb10g, whole fructus trichosanthis 30g, fried almond10g, and fried prickly heat 30g.

30g of gypsum, 0/0g of gardenia/kloc, 0/5g of Polygonum cuspidatum/kloc, and 0/5g of radish seed/kloc.

Cornus officinalis 15g, American ginseng 15g.

Decoct with water, 1 ~ 2 doses/day, once every 4 ~ 6 hours by oral administration or nasal cavity.

Add and subtract:

For those with high fever, delirium or even delirium, give Angong Niuhuang Pills from above.

Radix Aconiti Lateralis Preparata, Os Draconis preparata and Concha Ostreae are added for patients with cold limbs and excessive sweating;

Chinese patent medicine: Shenmai injection, Shenfu injection, Tanreqing injection, Xuebijing injection, Xiyanping injection and Reduning injection can be selected.

3. The above traditional Chinese medicine decoction, Chinese patent medicine and traditional Chinese medicine injection are not used as prevention, and should be treated with integrated traditional Chinese and western medicine at an early stage.

(5) Strengthen the support for the treatment and prevention of complications. Pay attention to rest, drink plenty of water, increase nutrition, give a digestible diet and keep the balance of water and electrolyte. If there is obvious hyponatremia, sodium chloride should be actively supplemented. For hypokalemia, potassium chloride, potassium aspartate and other potassium supplements should be given. We must closely observe the condition and monitor and prevent complications. Antibacterials should be used when secondary bacterial infection is clear or there is enough evidence to suggest secondary bacterial infection.

(6) Treatment of severe cases. For details, please refer to the treatment of severe cases in Medical Treatment Experts for Human Infected with H7N9 Avian Influenza.

Seven, hospital infection prevention and control

Strictly regulate the prevention and control measures of nosocomial infection in medical institutions that treat patients infected with H7N9 avian influenza. Follow the principle of standard prevention and take preventive and control measures according to the route of disease transmission. The specific measures are based on the Technical Guidelines for Hospital Infection Prevention and Control of Human Infections with H7N9 Avian Influenza (version 20 13).

Eight, turn professional or discharge standards

(1) Patients who need long-term hospitalization due to serious basic diseases or complications can be transferred out of the isolation ward for further treatment after being tested negative for H7N9 avian influenza virus nucleic acid twice in a row.

(2) The body temperature is normal, the clinical symptoms basically disappear, and the nucleic acid test of human infected with H7N9 avian influenza virus in respiratory tract samples is negative twice in a row, so you can leave the hospital.