Lecture of the flu (Grippe)

2021-03-23 12:00 AM

Easily destroyed at normal temperature, well-tolerated at low temperatures. Viruses have 3 types of antigens.


Influenza is an acute respiratory infection caused by influenza viruses such as A, B, and C. The disease has a sudden onset of high fever, headache, body aches and other respiratory signs, easily leading to pneumonia, high mortality rate.

Research history

In the twentieth century, many pandemic influenzas occurred with high morbidity and mortality rates. However clinical disease has been described many centuries ago (A Hirsd, 1881-1886). In 1933 W. Smith, C.Andrews, P.Laidpow identified influenza A virus. In 1940 T.Francis and T. Magill discovered influenza B virus, in 1949 R. Taylor discovered influenza C virus. In molecular biology techniques, scientists have identified the culprit that caused the first pandemic of influenza in 1918-1919 (Spanish flu) is the influenza A virus strain, which caused the death of 20 million people, pandemic Asian flu 1957-1958 was caused by influenza A, strains H2N2, causing about 1 million deaths. Influenza Hong Kong in 1968-1969 due to influenza A H3N2, Russian flu in 1977 due to the strain of H1N1 ... The influenza A virus has the ability to change the antigenic structure. The process of hybridization, recombination between influenza A virus in humans, influenza A virus in animals will form a new influenza virus strain. Therefore, influenza A virus is the culprit in pandemics, influenza B virus often causes epidemics. Region, influenza C virus often causes dispersing epidemics. A pandemic flu occurs every 10-14 years. A pandemic influenza A (H5 N1) spreading from poultry to humans occurred in Hong Kong is in danger of spreading into a pandemic.



Influenza virus belongs to the Ortho myxo viride family. It is spherical, spherical, and about 80-100 mm in size. Easily destroyed at normal temperature, well tolerated at low temperatures. Viruses have 3 types of antigens.

S antigens (Soluble) are soluble antigens, based on the structure of S antigens, the 1953 international conference on influenza named and classified the serotypes of influenza viruses as A, B, and C. .

H antigen (Hemagglutinin) is an antigen that prevents red blood cell agglutination to help the virus attach to cells.

Neuraminidase (N) is an antigen with enzyme properties that help viruses enter cells.

The genetic makeup of the influenza virus is a single stranded envelope of RNA. The envelope nature is glycoprotein, the H and N antigens are the components of the influenza virus envelope.


During an epidemic, people are the source of the disease.

In addition to the epidemic, the source of influenza A virus is animals. Poultry species, such as migratory birds, are now known sources of influenza A virus (H5 N1).


Person-to-person direct contact through inhalation through tiny droplets of saliva and nasopharynx fluid that carries flu virus.

Direct transmission from birds to humans: in localities with avian influenza, the possibility of direct transmission from poultry, poultry products to humans is very high.

Sense of the body

People of all ages can get sick, teenagers are susceptible to disease.

The elderly and those with chronic respiratory diseases are susceptible to serious illness with a high mortality rate.

After influenza, the body has specific immunity, the duration of immunity depends on the level of antigenic variation and the number of previous infections.

When the new influenza virus type appeared, people of all ages had the same susceptibility to disease.

Mechanism of pathogenesis and pathology

Mechanism of pathogenesis

Influenza viruses have a special affinity for respiratory epithelial cells. Thanks to the H and N antigens they attach and enter the respiratory epithelial cells, they multiply and grow very quickly, disrupting cell metabolism and disrupting cells, and then continuing to destroy the cells of the respiratory tract. other cells

In the respiratory tract mucosa, influenza virus is resisted by non-specific immune factors of the body such as nasopharyngeal fluid, alveolar fluid, IgA…. If they cross this barrier, they penetrate into the blood, attach to the surface of red blood cells around the body, cause blood virus infection, then enter the organs.

Injury from pathological surgery

During the process of entering the body, the flu virus damages many organs.


Is a nonspecific inflammatory response.

Congestion, edema along respiratory organs.

Bronchitis secretion.

Diffuse bronchitis with pseudo-necrotic mucosa.

Bronchial obstruction due to discharge.


The pleura is peeling off each piece.

Pulmonary abscess, multifocal bronchial abscess.

Organized lymph node proliferation.

Meninges, blood cells around the blood vessels.

Liver, spleen: No parenchymal damage.


Divide the clinical form

Light form.

Can fit.

Severe and complicated form.

Atypical form.

Symptoms study according to each clinical form

Conventional flu

Incubation period:

2-4 days (as short as 24 hours) are usually asymptomatic

Onset period: 

Usually suddenly with a high fever of 39-40 0 C, accompanied by chills, headache, dizziness, nausea and general aches, fatigue, not wanting to work

Full-play period:

Syndrome of infectious and poisoning with high fever continuously at 39- 400 C, the time of fever 4-6 days, when the fever is gone, the temperature decreases rapidly. Some patients with fever type "V flu" have a high fever, the temperature drops, then rises again, and then drops for the second time.

Fatigue patients suffer from poor appetite and sleep, dry lips, dirty tongue, rapid pulse in blood pressure, yellow urine.

Peripheral blood leukocytes number did not increase, Lymphocyte rate increased, blood collection rate did not increase.

Respiratory Syndrome: Common symptoms are:

Inflammation of the upper respiratory tract: runny nose, sneezing, sore throat, dry cough, congested eyes, watery eyes, photophobia.

Pharyngitis and trachea: Patient is hoarse, dry cough.

Acute bronchitis pneumonia: chest pain, difficulty breathing, cough to cough up sticky white sputum. On lung examination, a screeching, or some small moist crackling, was found.

Lung X-ray: Usually does not reflect clinical signs in the lung.

Other symptoms:

Constant headache, pain in the temples, forehead, sometimes bouts accompanied by dizziness, tinnitus.

Whole body aches and pain in muscles and joints, pain along the spine, pain across the lower back, massage muscles and joints are less pain

Severe and complicated flu, influenza A (H5 N1)

Malignant flu form (dark form):

Patients with flu symptoms often have malignant anxiety syndrome and delirium, possibly having convulsions. Grayish skin, dark circles, and pale lips.

Rapid pulse, drop in blood pressure.

Bleeding under the skin.

Difficulty breathing, cough with pink frothy sputum.

Bloating, big liver, loose stools.

Little urination, impaired kidney function ...

Lung examination reveals moist bursts, X-ray of the lesions spreads one lobe, one side, or two lung progresses rapidly.

If not treated in time, patients usually die 1-3 days after cardiopulmonary respiratory failure. An autopsy is an image of mass pneumonia, multi-organ damage

Complicated flu:

Superinfection: Common caused by bacteria Streptococcus, Peumococus, bacillus Pfciffer ...

Superinfection in the ENT, pharyngitis, inflammation of the oral mucosa, abscess of the pharynx, pharynx, parotid gland inflammation, sinusitis. Common ear laryngitis with pseudomembranous in children.

Superinfection in the lungs, pleura: Common bronchitis inflammation, increased fever, cough, chest pain, difficulty breathing. Examination of the lungs found his snoring and hissing moisture.

Pneumonia - bronchitis: Usually appears on day 4-6 of the disease. High fever of 39-400 C, worsening general condition, difficulty breathing, breathing failure, this is a serious complication, mortality 25-30%

Complications in the pleura:

Pleural effusion.

Pleural effusion: When there is accompanying bacterial infection, fever suddenly increases 39- 40 0 C, chest pain, difficulty breathing increases.

Other complications:

Meningitis: Usually secondary to otitis media, necrosis in other superinfection

Myocarditis, endocarditis, pericarditis ...

Other types of flu

Mild flu:

Patient has no fever or mild fever, with prominent respiratory tract inflammation. Many cases must be diagnosed with a Hirst reaction

Influenza has a distinct medical condition:

Gastrointestinal flu: Patients often have abdominal pain, nausea and vomiting, frequent loose stools, sometimes pelvic pain easily confused with acute appendicitis.

Influenza has a meningeal reaction: high fever, sore throat, headache. Signs of meningeal (+), but cerebrospinal fluid is normal

Influenza with neuritis: The cranial nerve (7th cord, III wire ...) with corresponding symptoms

Implementing the quadrants


Sudden onset, high fever for 4-7 days.

Expression of respiratory inflammation, or complications in the lungs.


The number of peripheral blood leukocytes is normal or decreased, the Lymphocyte increases.

To diagnose the pathogen must be based on specific tests.

Hirst reaction: A serum reaction based on the principle of erythrocyte agglutination inhibition (HI) technique. Take blood 2 times, 7-10 days apart for the first time, as soon as possible. A positive result is when the antibody titre reaches 1/1280 or the antibody titer for the second antibody is 4 times or more.

Complement combination reaction.

Immunofluorescence response: Allows early diagnosis, with accurate results at the rate of (+) 60- 70% after 3-4 hours.

Virus isolation: Valuable in diagnosis. Get nasopharyngeal fluid, take blood, transplant on chicken embryo organization.

Testing techniques: Elisa, Mac- Elisa, PCR, RT- PCR, electron microscope ... are applied to identify influenza virus strains, especially when new types appear.


Flu usually occurs in the winter and spring, at the same time many people get sick.

Patients with a history of contact with people with influenza, or poultry exposure to flu

Differential diagnosis

Nasopharyngitis, caused by bacteria.

Inflammatory diseases of the respiratory tract caused by other viruses.

Dengue Dengue in the early days of the disease.

Bronchitis, acute pneumonia ... caused by bacteria.


The principles of treatment

Ordinary flu patients

Isolate and rest in bed until fever is gone, in case of complications. Eat liquid with enough nutrition, drink enough water, increase vitamins.

For patients with tranquilizers: Valium, rotunda ... expectorants, sirocodein, tecpincodein.

Antibiotics are only used in case of bacterial superinfection.

Severe (malignant) influenza patients, many H5 N1 influenza viruses

Suspected patients must be isolated.

Take antiviral drugs as soon as possible, right from the first days of illness.

Resuscitation against respiratory failure is fundamental.

Treatment of superinfection, complications of multi-organ failure.

Treat the cause

Antiviral drugs: Recommended for severe cases.

Tamiflu (Oseltamivir)

Children from 1- 13 years old: use an oral solution depending on body weight.

<15kg: 30mg x 2 times / day for 7 days.

16-23 kg: 45mg x 2 times / day for 7 days.

24-40kg: 60mg x 2 times / day for 7 days.

Adults and children over 13 years: 75mg x 2 times / day for 7 days.

Need to monitor liver function, kidney to adjust accordingly.


1-9 years: 50mg x 2 times / day x 7 days.

> 9 years: 100mg x 2 times / day x 7 days.

Ribavirin 400mg tablet

1- 9 years: 1 tablet x 3 times / day x 7 days.

> 9 years old: 2-3 tablets x 3 times / day x 7 days.

The anti-influenza gammaglobulin comes from human serum of blood donors

Adults: 1- 6ml intramuscularly one time.

Children: 1- 3ml intramuscularly 1-2 times.

The Russian anti-flu serum in powder form is sprayed into the nose 1-2 times

InTerferon: To protect cells that have not been destroyed by virus.

Treatment according to the pathogenetic mechanism

Treatment of acute respiratory failure

Oxygen 1-5 liters / min to SPO2> 90%.

High-pressure oxygen breathing: When breathing oxygen through the nose does not improve the hypoxia, start breathing with CPAP = 5 cm H2O, then adjust the CPAP level according to the patient's condition with a change of 1 cm H2O to maintain SPO2> 90%. The maximum CPAP level can reach 10m H 2 O.

Artificial ventilation when the two above measures do not improve respiratory conditions.

Rehydration electrolyte infusion: Average 1200 - 1500ml / day for adult patients, pay attention to avoid pulmonary edema.

Cardiopulmonary, anti-shock.

Cocticoid: It is possible to use drugs.

Methylprenisolon 0.5 - 1.0 mg / kg / day x 7 days, by slow intravenous injection.

Hydrocortisone 100mg x 2 times / day for 7 days.

Depersolon 30mg x 2 times / day for 7 days.

Prednisolone 0.5 - 1.0 mg / kg / day x 7 days orally.

Antibiotics: High dose for the prevention and treatment of bacterial superinfection such as Cephalosporin, Quinolone ...

Ensure nutrition and care: Feeding nutritious milk powder through gastric tube. Intravenous feeding if inedible.

Anti-ulcer: for patients to lie in a water cushion, massage to change positions.

Respiratory care: Help the patient cough, spit and vibrate the chest, suck phlegm.

Criteria for discharge

Fever is gone 7 days after stopping antiviral and antibiotic drugs.

Blood test, Cardiopulmonary x-ray is stable.


General prevention

Early detection, isolation of patients, and limitation of spread.

Medical personnel who come into contact with patients must have adequate protective equipment. Prophylaxis with antiviral drugs as indicated.

Tamiflu 75mg x 1 tablet / day for 7 days.

When there is a severe flu epidemic, the death rate is high.

Specific disease prevention

Prevention of influenza for humans with vaccines, currently there are two types of vaccines: live vaccine with reduced toxicity and vaccine dead. Endoderm injection 0.1ml injection 2 times 14 days apart.

Vaccination against influenza for poultry and animals at risk of disease. Destroy infected poultry family. Do not slaughter or eat infected poultry and cattle.