A stream
Introduction
Introduction to A stream Influenza A (H1N1) virus is a type A influenza virus carrying a H1N1 subtype swine influenza virus strain containing ribonucleic acid gene fragments of three influenza viruses, avian influenza, swine influenza and human influenza, and possessing Asian pigs. Influenza and African swine flu virus characteristics. Medical tests have shown that mainstream antiviral drugs are currently effective against this strain, and photographs from the US Centers for Disease Control and Prevention indicate a negative reaction to the H1N1 influenza virus. On April 30, 2009, the World Health Organization, the Food and Agriculture Organization of the United Nations and the World Organisation for Animal Health announced that they agreed to use the A(H1N1) influenza to refer to the epidemic at the time and no longer use the term swine flu. The Chinese health department has renamed the original person infected with swine flu as the H1N1 flu. The Ministry of Health of China issued the 8th Announcement of 2009 on April 30, 2009 to explicitly include the H1N1 flu (formerly known as human swine flu). The Class B infectious diseases are regulated by the Law on the Prevention and Control of Infectious Diseases, and prevention and control measures for Class A infectious diseases are adopted. basic knowledge The proportion of illness: 0.06% Susceptible people: no special people Mode of infection: respiratory transmission Complications: bronchitis, pneumonia, pleurisy
Cause
A stream cause
Environmental factors (25%):
Swine Influenza is an acute, zoonotic respiratory infectious disease caused by influenza A (type A) influenza virus. This disease occurs frequently in pigs and rarely causes pig death (pig The case fatality rate is 1-4%. Humans are rarely infected with swine flu virus, but some cases of human swine flu have also been found, most of whom have direct contact with sick pigs.
Viral infection (75%):
In March 2009, people infected with swine flu virus in Mexico and the United States were influenza A virus, H1N1 subtype swine influenza virus strain, which contained swine flu, avian flu and human flu. The gene fragment is a new type of swine flu virus that can infect humans. The clinical early symptoms of human infection with swine flu are similar to those of flu. There are fever, cough, fatigue, loss of appetite, etc., and symptoms such as diarrhea or vomiting may also occur. Can progress rapidly, sudden high fever, pneumonia, severe respiratory failure, multiple organ damage, leading to death.
Etiology
The swine flu virus belongs to the family Orthomyxoviridae (Int., Influenza virus A). The typical virus particles are spherical, 80 nm to 120 nm in diameter, with a capsule, and there are many radial projections on the capsule. Glycoproteins, hemagglutinin HA, neuraminidase NA and M2 proteins, nucleocapsids in the viral particles, spirally symmetric, 10 nm in diameter, swine influenza virus is a single-stranded negative-strand RNA virus, genome is approximately 13.6 kb, consisting of 8 independent fragments of different sizes, although a variety of influenza virus serotypes can be formed between different subtypes, the serotypes that cause human infection with swine influenza virus are mainly H1N1, H1N2 and H3N2.
The swine flu virus is a capsular virus, so it is sensitive to organic solvents such as ether, chloroform and acetone. The virus infectivity is destroyed by 200 mL/L ether at 4 ° C overnight; the oxidants, halogen compounds, heavy metals, ethanol and formaldehyde are also Sensitive, 10 g / L potassium permanganate, 1 mL / L liters of mercury for 3 min, 750 mL / L ethanol for 5 min, 1 mL / L iodine 5 min, 1 mL / L hydrochloric acid for 3 min and 1 mL / L formaldehyde for 30 min, can be extinguished Live swine flu virus, swine flu virus is sensitive to heat, can be inactivated at 56 °C for 30 min; sensitive to ultraviolet light, but inactivation of swine flu virus with ultraviolet light can cause multiple repetitive activities of the virus.
Epidemiology
In the so-called "New Jersey Incident" in the United States in 1976, about 500 people were infected with the swine flu H1N1 subtype virus, which was the same as the virus isolated from pigs at the time. It was first confirmed that under natural conditions, the swine flu virus can be The pig spread to people. In October 1999, a 10-month-old girl from Hong Kong was infected with the swine flu virus H3N2. It has been fully recovered. Over the years, people from all over the world have been infected with different strains of swine flu virus, but there is no report. A large-scale epidemic has recently caused human swine flu outbreaks in parts of Mexico and the United States. The World Health Organization pointed out that the cases infected in Mexico and the United States belong to the same strain of the H1N1 subtype swine flu virus.
(1) Source of infection
Mainly for sick pigs and pigs carrying viruses, people infected with swine flu virus have also been confirmed to transmit the virus, and animals infected with the virus can spread.
(2) Ways of transmission
It is mainly transmitted by the respiratory tract. It can also be transmitted by contact with infected pigs or their feces, surrounding polluted environment or aerosols. Some strains such as H1N1 can be transmitted from person to person. The route of infection is similar to that of flu. It is through coughing or sneezing by infected people.
(3) Susceptible people.
It is generally susceptible. Most of the patients are between the ages of 25 and 45. The current report is mainly for young adults and should pay attention to the elderly and children.
(4) High-risk groups
Those who work in the pig industry are those who have been to pigs, sales and slaughter in the first week before the onset of illness, and laboratory workers exposed to swine flu virus infection materials are at high risk.
Human infection with swine flu often occurs in winter and spring, and swine flu infection usually occurs in summer and autumn.
Pathological changes: The pathological changes of swine influenza are mainly in the respiratory organs, nasal, pharynx, larynx, trachea and bronchial mucosa congestion, swelling, surface covered with viscous liquid, small bronchi and bronchiole filled with foam-like exudate The chest cavity and the pericardial cavity accumulate a large amount of cellulose-mixed serum. The lesions of the lung often occur in the apex, the heart leaf, the middle leaf, the back and base of the temporal lobe, and have obvious boundaries with the surrounding tissue. The color is from red to purple. , collapse, solid, toughness like leather, splenomegaly, cervical lymph nodes, mediastinal lymph nodes, bronchial lymph nodes, most juice.
Prevention
A stream prevention
(1) Controlling the source of infection
To carry out human and swine influenza surveillance, once pigs or other animals are found to be infected with swine influenza virus, the source of the epidemic should be thoroughly disinfected in accordance with the relevant provisions of the Animal Quarantine Law to isolate patients and suspected patients.
(2) cutting off the propagation path
For farms where sick pigs are found, stalls that sell sick pork, patients' units, households, etc. are disinfected, and wastes such as dead pigs should be destroyed or buried in the field immediately; the outpatient and ward of patients should be treated according to bird flu. The SARS standard is isolated and disinfected; the specimens are transported and disposed of according to the requirements of unexplained pneumonia cases.
(3) Protecting healthy people
Develop good personal hygiene habits, sleep adequately, exercise diligently, reduce stress, and be adequately nutritious; avoid respiratory symptoms such as flu-like symptoms (fever, cough, runny nose, etc.) or pneumonia; pay attention to personal hygiene, often use soap and water Wash your hands, especially after coughing or sneezing; avoid contact with pigs or places where there are pigs; avoid going to crowded places; cover your mouth and nose with a tissue when you cough or sneeze, then throw paper towels into the trash; if you appear outside the country Influenza-like symptoms (fever, cough, salivation, etc.) should be treated immediately (when wearing a mask), and explain to local public health agencies and inspection and quarantine departments.
(4) Strengthening the sense of hospital control measures
Isolation and wearing surgical masks for suspected patients or confirmed patients; medical personnel should do personal protection, strengthen hand hygiene, use hand disinfection for hand disinfection; medical staff in key departments such as fever clinics and infectious diseases departments should wear surgical Masks, if necessary, wear goggles or protective masks; indoor ventilation should be strengthened for key departments such as fever clinics and infectious diseases.
Swine flu vaccine: Currently only the swine flu vaccine for pigs has not been specifically used for humans. As far as the current situation is concerned, the common flu vaccine has no obvious effect on preventing human swine flu.
Complication
A stream of complications Complications, bronchitis, pneumonia, pleurisy
Easy complicated by bronchitis, pneumonia and pleurisy.
Symptom
A stream symptoms Common symptoms High fever Acute respiratory distress syndrome Diarrhea Respiratory failure Fatigue sepsis Whole blood cell reduction Shock pleural effusion Eye redness
The incubation period for human infection with swine flu is generally about 1 to 7 days, which is longer than the flu and bird flu incubation period.
(a) clinical symptoms
The early symptoms of human swine flu are similar to those of ordinary human flu, including fever, cough, sore throat, body aches, headache, chills and fatigue, some may also have diarrhea or vomiting, muscle pain or fatigue, red eyes, etc. .
Some patients can progress rapidly, fierce, sudden high fever, body temperature over 39 ° C, and even secondary severe pneumonia, acute respiratory distress syndrome, pulmonary hemorrhage, pleural effusion, whole blood cell reduction, renal failure, sepsis, shock and Reye Syndrome, respiratory failure and multiple organ damage lead to death.
(two) signs
The signs of the lungs are often not obvious, and some patients may smell wet rales or have signs of lung consolidation.
Examine
A stream inspection
First, laboratory 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 decrease, and platelets decrease.
2. Serological diagnosis: indirect ELISA, antigen capture ELISA, fluorescence immunoassay, etc.;
3. Reverse transcription-polymerase chain reaction (RT-PCR): Because of its simplicity, rapidity, sensitivity, and specificity, PCR technology has been used for the detection of swine influenza virus genes and molecular epidemiological investigations;
4. Virus isolation: The swine influenza virus is isolated from the patient's respiratory specimens (throat swab, oral sputum, nasopharyngeal or tracheal aspirate, sputum or lung tissue). Common methods include chicken embryo inoculation and cell culture. Among the existing diagnostic methods, the virus separation method is more sensitive, but it takes 2-3 weeks.
Second, chest imaging
In the case of pneumonia, flaky images can be seen in the lungs. In severe cases, the lamella images are extensive.
Diagnosis
A stream diagnosis and identification
Diagnostic criteria for human infection with swine flu
1. Medical observation cases: I have been to the swine flu epidemic area, or have a close contact with patients with sick pigs and swine flu, and those who have clinical manifestations of influenza within 1 week are listed as medical observation cases for 7 days of medical observation. (Depending on the condition, you can be isolated at home or hospital).
2. Suspected cases: I have been to an infected area, or have a close contact with sick pigs and swine flu patients (also epidemiological history is unknown), clinical manifestations of influenza within 1 week, respiratory secretions, pharyngeal test, Liquid, serum H subtype virus antibody positive or nucleic acid test positive.
3. Clinically diagnosed cases: Those diagnosed with suspected cases and who have a history of common exposure are diagnosed as confirmed cases.
4. Confirmed cases: specific viruses were isolated from respiratory specimens or serum; RT-PCR detected the above specimens, there was swine influenza virus RNA, confirmed by sequencing, or two times the serum antibody titer increased four times, can be diagnosed as human Infected with swine flu.
Differential diagnosis
The clinical manifestations of common flu are:
1, simple influenza: acute onset, body temperature 39 ~ 40 ° C, with chills, fatigue, headache, muscle and joint pain and other systemic symptoms, respiratory tract symptoms are mild, may have runny nose, nasal congestion, dry cough. Physical examination: acute illness, pharyngeal congestion and redness, no secretions, and dry voice in the lungs.
2, pneumonia-type influenza: less common, mostly in the elderly, children, the original heart and lung disease population. Causes: Primary toxic pneumonia, secondary bacterial pneumonia, mixed bacterial virus pneumonia. Performance: high fever continues to retreat, severe cough, hemoptysis, shortness of breath, cyanosis, lungs can smell and wet voice. The chest radiograph suggests that there are scattered flocculities in both lungs. The sputum cultures no pathogenic bacteria to grow, and the influenza virus can be isolated. It can die due to respiratory and circulatory failure and has a high mortality rate.
3. Toxic influenza: characterized by damage to the central nervous system and cardiovascular system. The performance is high fever, blood pressure, eyesight, convulsions, meningeal irritation and other encephalitis meningitis symptoms.
4, gastroenteritis-type influenza: rare, with diarrhea, abdominal pain, vomiting as the main clinical manifestations.
