Lecture for acute respiratory viral infection

2021-03-23 12:00 AM

In recent years, the severe acute respiratory viral infection (SARS) epidemic, high mortality rate, tends to increase and is a current problem in world health.


An acute respiratory viral infection is a common group of diseases in humans, caused by viruses. The general clinical feature is the manifestation of acute respiratory infections with specific symptoms caused by each virus.

Research history

The group of acute respiratory viral infections contains more than half of all acute illnesses. Every year, 30-50% of adults have to quit work and 60-80% of children miss school because of acute respiratory viral infections. The disease accounts for 2/3/3 of the total number of acute respiratory infections.

For a long time, the cause of the disease is believed to be pneumococcal bacteria, streptococci, staphylococcus bacteria, Haemophilus influenza, Micrococcus Catarrhalis ... up to now, 8 groups with more than 200 types of virus have been identified. Various antigens cause acute respiratory disease.

The diagnosis and determination of the pathogen and clinical classification of this group of diseases face many difficulties. Many studies have shown that: The same clinical scene, possibly caused by a viral infection and vice versa, just one virus can cause many different clinical symptoms, so this group of diseases has clinical characteristics. general screening. The most common clinical syndromes are "cold", laryngitis (Croup syndrome) acute tracheitis and acute pneumonia.

Each group of viruses often causes common and uncommon syndromes, causing illness mainly at certain ages.

Diagnosis of the disease must be based on virus isolation tests and serological reactions.

In addition to influenza viruses (A, B and C), 8 common viruses that cause acute respiratory infections are Rhinovirus, corona virus, Respiratory Syncytial virus (syncytial respiratory virus), Parainfluenja virus (intestinal virus. and Herpes Simplex virus and Human-Pneumo viruses (viruses that cause pneumonia in humans).

In recent years, the severe acute respiratory viral infection (SARS) epidemic, high mortality rate, tends to increase and is a current problem in world health.

Common and rare clinical syndromes caused by viruses.


Viruses group

Common syndrome

Less common syndrome

Rare syndrome


Virut Rhino


Chronic bronchitis, bronchial asthma

Pneumonia in children


Virut Corona


Chronic bronchitis, bronchial asthma

Pneumonia End bronchitis


The syncytial virus

Pneumonia, bronchitis in children

Colds in adults

Bronchitis in the elderly


Sub-influenza virus

Cruop and inflammation of the lower respiratory tract in children

Sore throat colds

Tracheitis, bronchitis in adults


Virut Adeno

Colds, sore throats in children

The outbreak of respiratory disease in recruits

Pneumonia in children and immunocompromised people


Whole Chip

Fever of unknown origin

Pharyngitis, arthritis



Virut Herpes Simplex

Inflammation, ulcers of the oral mucosa and children's gums, pharyngitis, acute amydal inflammation in adults

Tracheitis, pneumonia in immunocompromised patients

Disperse infection in immunocompromised patients


Hu man-Pneumatic virus

Rhinitis, laryngitis

Bronchitis, pneumonia in immunocompromised patients

Infectious pneumonia is widespread in immunocompromised patients

Rhinitis infections (Rhinitis infections)


Rhinovirus (Rhinovirus) of the Picornaviridae family, small in size 15-30 mm, containing RNA, without an envelope. Easily inactivated by acid solution so the gastric juice kills Rhinovirus.

It grows well at 33-34 0 C in the sinuses and better in the lower respiratory tract mucosa.

Currently detected more than 100 serotypes and some subtypes of Rhinovirus.


As a patient and carrier of the virus, the patient eliminates the virus one day before having the first clinical symptoms, until the disease is cured.


The disease is transmitted through the respiratory tract, spread through contact with the patient's utensils very rare because the Rhinovirus can be killed in the outside environment.

Sense of the body

The younger the age, the higher the prevalence, especially in children under 6 years old.

The disease occurs all year round or causes epidemics in winter, spring when the weather changes.

After being infected, there is immunity to the infected virus, but weak immunity only exists for a few weeks. So a person can get sick 2-3 times a year.

The immune mechanism of Rhinovirus infection has not been fully studied. Some studies show that having a co-antibody significantly reduces the incidence.

Mechanism of pathogenesis and pathology

Mechanism of pathogenesis

Rhinovirus develops locally in the nasopharyngeal mucosa and larynx, does not penetrate into the blood. With a cold, the peripheral nervous system and body temperature regulation are disrupted by the shrinking of the systemic capillaries, the decrease in blood supply in the nasal mucosa, allowing the virus to enter and grow.

Rhinoviruses enter cells through specific receptors, mainly intracellular binding molecules (ICAM-1).

Pathological anatomical injury

Photos of pathological anatomical lesions in patients and in experiments showed oedema of the nasal mucosa, congestion, infection with polymorphonuclear leukaemia cells, eosinophils, lymphocytes and cytoplasm. . The mucous glands increase activity, the sinuses are congested, which can lead to sinus obstruction.


Incubation period: 1- 4 days.

Clinical manifestations: Mainly cold syndrome, sudden onset, at first sore throat, sneezing, runny nose. Nasal mucosa congestion, fatigue may be accompanied by fever, taste and smell may be disturbed.

In children: A lot of runny noses can have a cough congestive eye conjunctival, some cases may have bronchitis inflammation.

In adults: Rhinovirus can aggravate certain chronic lung diseases. The disease progresses in about 4-9 days. Some cases have complications such as otitis media, sinusitis due to inflammation of the ear canal and sinus cavities.


Rhinovirus is the main cause of the cold syndrome, diagnosis is not difficult. However, other diseases with similar clinical conditions must be excluded, and complications of the disease must be detected.

Diagnosis is confirmed based on virus isolation, through culture. Specimens are secretions from the nose and throat, serum tests to detect antibodies. In fact, these tests are rarely conducted due to benign disease progression, Rhinovirus has many serotypes.


Cases without complications: Symptomatic treatment.

Cases with complications: Such as otitis media, sinusitis requires antibiotic treatment. There is no need for antiviral drugs.


Interferon can be sprayed as an aerosol into the nose of the sinuses.

A vaccine to prevent disease. However, because Rhinovirus has many types and the immune mechanism is not clear, the use of vaccines is still a matter of consideration.

Coronavirus infection and SARS


Coronavirus has the size of 80-160mm and has many shapes, containing 1 strand of RNA with a shell from the virus shell emitting rings of light like scattering the sun (Corona - scattering ring).

In human isolated 3 serotypes B814, 229 E and OC 43, Coronavirus is very difficult to cultivate, some strains only develop on culture specimens taken from the trachea.


The disease spreads through the respiratory tract.

The source of the disease in the epidemic is the patient. In recent years, animals such as civet ... have been identified as the source of the disease.

The antibody rate to Serotype 229 E and OC 43 in the community is 12-18%.

Coronavirus infection accounts for 10-20% of the total number of viral diseases with cold syndrome.

The disease usually occurs in late autumn-winter, early spring when the number of patients infected with Rhinovirus has decreased. Coronavirus infection usually occurs cyclically, depending on the serotype. A 2-year cycle for OC 43 and 2- 4 years for 229 E.

In November 2002, an outbreak of severe high mortality Coronavirus (SARS) occurred in China's Guangdong province, spreading rapidly to 28 countries, including Vietnam. The number of patients according to statistics is 792, the mortality rate is 11%.


The incubation period is about 3 days.

The clinical picture is similar to that of Rhinovirus infection lasting about 6-7 days. Nasal mucus secretion is caused by Coronavirus more than due to Rhinovirus infection.

Coronavirus infection can cause infant pneumonia, lower respiratory tract infections in rookie camps and exacerbate cases of chronic bronchitis.

The malignant form of Coronavirus infection occurs very quickly: The patient is anxious, struggling, delirious or convulsive. Accompanied by fever, gray skin, dark circles, photophobia, rapid blood pressure drop, shortness of breath, cough with pink foam and phlegm, bleeding under the skin.

X-ray of the lungs: Images of lobar pneumonia, rapid progression.

Patients usually die in cardiac pulmonary insufficiency after 1-3 days.


Treatment is similar to rhinovirus infection, patients should be isolated, monitored for detection and respiration promptly. Treatment of the prevention and limitation of complications

Severe cases (SARS): High doses of Corticoid artificial respiration oxygen, treatment of multiorgan failure


Early detection isolates cases with suspected Coronavirus such as Fatigue cough.

Due to the lack of understanding of the relationship between serotypes, immune mechanisms, as well as adequate research, there is no vaccine for disease prevention.

Infection with a respiratory syncytial virus (RSV)



Syncytial respiratory virus belongs to the family Paramyxoviridae, with a diameter of 150-300mm and a shell. When multiplying, syncytial viruses are capable of fusing neighbouring cells into a large cytoplasm with many nuclei.

RSV has a thin strand of RNA containing 10 specific proteins. The RNA of the syncytial virus is located in a spiral Nucleocapsid, the outer lipid shell contains 2 Glucoproteins: Protein G helps the virus attach to the cell and Protein F helps the virus to enter and merge with the cell.

RSV has 2 subtypes (AvĂ  B), which differ in epidemiological and clinical characteristics caused by each subtype.

The source of the pathogen is the receptor of the body

The source of the disease is the patient. The disease spreads through the respiratory tract.

Ages often infected are children 1- 6 months old is more common in children 2-3 months old. The incidence can be as high as 100% in kindergartens.

RSV is the main cause of respiratory disease in infants, especially the lower respiratory tract in infants. RSV accounts for 20-25% of pneumonia patients and 75% of hospitalized bronchitis patients of infancy and childhood. An estimated 50% of newborns are at risk for RSV infection.

Older children and adults, often re-infection with RSV. The disease spreads strongly in families, can cause up to 40% of family members infected with RSV can infect paediatric staff up to 20-25% during outbreaks. Infection with syncytial respiratory virus is a worldwide disease, easily epidemic in late autumn, winter or late spring and can last up to 5 months.

The immune response to RSV infection has not been adequately studied. The presence of antibodies to neutralize class IgA in volunteer nasal secretions has a better protective effect than antibodies in the serum.


Incubation period: 4-6 days.

In new-borns: The disease starts with mild fever, runny nose, and coughing 25-40% of infected children present with inflammation of the lower respiratory tract such as pneumonia, bronchitis. The disease progresses especially seriously in children with congenital heart disease, congenital respiratory disease or immunodeficiency, the mortality rate can be up to 37%.

In adults: Mainly the manifestations of colds such as the runny nose, sore throat, cough with mild fever and fatigue, headache. Pneumonia can be seen in elderly people with chronic lung disease.


Diagnosis of RSV infection is suspected when the infant has difficulty breathing, many children have the same disease in a group

Diagnosis is confirmed by virus isolation from phlegm, nasal discharge, throat wash, virus detection by immunofluorescent ELISA techniques


Treatment of lower respiratory tract RSV infection.

Respiratory therapy: Oxygen and bronchospasm. Endotracheal intubation, artificial ventilation in the absence of severe oxygen.

Ribavirin nasal spray: Applied to some infants has been shown to be effective in restoring respiratory function, including improving blood gas status in infants. However, there has not been a clear effect of ribavirin in adults with RSV-induced pneumonia.


General prevention applies the same preventive measures as other respiratory viral infections

Specific disease prevention: The vaccine to prevent RSV is still being studied. Vaccines made from the inactivated virus appear to be ineffective. Vaccines are made from purified F and G surface Glycoproteins of RSV, and the virulence reduction river RSV virus vaccines are under study.

Sub-influenza virus infection


Sub-influenza virus belongs to the Paramyxoviridae family, the genus Paramyxovirus, size 150-250mm, contains a thin strand of RNA surrounded by a helix-shaped Nucleocapsid and encoded with 8-9 specific proteins, the sub-influenza virus envelope contains 2 Glycoproteins with 2 with different functions, 1 type has coagulation activity and the other has fusion function with sub-influenza virus cells with 4 serotypes. Type 1 (also known as Sendrai- virus) was discovered in Japan in 1953, type 2,3 and type 4 were isolated in 1960 with antigens that are similar to those of viruses of the Paramyxoviridae family (such as Mumps and Newcastle Virus)


Sub-influenza viruses cause respiratory illness depending on the type of virus and the age of the disease.

Type 1 is the main cause of "Cruop" syndrome in children. Type 2 can cause the same but milder illness.

Type 3 can cause illness in new-borns as early as the first month of life, while still transmitting passive antibodies from the mother.

Type 4 is less likely to be detected due to culture difficulties. Antibodies of subtype 1,2,3, commonly found in 8-year-old children, up to 22% of respiratory diseases are caused by a sub-influenza virus. This is a virus that causes a common respiratory disease after a syncytial virus (RSV) infection in young children.

Types 1 and 2 usually cause illness in the summer of odd years. Type 3 causes illness all year round, translating into an epidemic in the spring.

Sub-influenza virus infection accounts for about 5% of respiratory diseases cases in adults.


Incubation period: 3-6 days, maybe shorter in children.

The disease has a sudden onset in children: High fever is 50-80% runny nose, sore throat, hoarseness and cough, maybe cough "the man" and hissing breath. High fever, a sore throat that lasts can lead to "Cruop". Severe cases such as bronchitis, pneumonia often contract shallow, rapid wheezing and muscle contracting on the side.

Older children and adults: Clinical symptoms are milder, mainly cold, accompanied by a less common cough with inflammation of the lower respiratory tract.

The recovery period is usually as short as 1-2 days.


Clinical manifestations: Fever associated with respiratory inflammation or Cruop manifestation in young children

Testing: Isolation of virus from nasopharyngeal fluid need a differential diagnosis from Cruop manifestation due to other causes: influenza A virus, Hemophilus influenzas type B ...


Symptomatic treatment when there is only inflammation of the upper respiratory tract.

If there are manifestations of Crop, it is necessary to treat in the hospital with measures of oxygen breathing, artificial respiration, high dose corticoid ... antibiotics to prevent and treat symptomatic superinfection such as sinusitis, bronchitis, pneumonia due to bacteria.

Antiviral drugs: Ribavirin can be used to treat severe cases


The vaccine for the prevention of the sub-influenza virus is currently being studied

Adenovirus infection


Adenovirus (Adenovirus) belongs to the genus Mast adenovirus, size 70- 80mm. The shell has a polyhedron structure consisting of 20 equilateral triangles. Discovered by WP Rowe et al. In 1953. It is a virus containing DNA. Based on Genom DNA similarity, Adenovirus is divided into 6-7 subgroups. The capsid shell has 6 subunits that contain group and type-specific antigenic determinations, and another 5 subunits contain group-specific antigens.

Adenovirus in adults has 47 serotypes, some related to the variation of tumours in rodents, but not in humans.


The disease accounts for 3 to 5% of respiratory tract infections in children, less than 2% in adults.

Serotypes 1,2,3,5, usually cause illness in children, types 4.7, sometimes types 3, 14, 21, are common in rookie camps.

The disease occurs all year round, focusing on late autumn to spring.

After the disease, there are specific antibodies and almost only isopathic form. Almost 100% of the elderly have antibodies to the Adenovirus Serotype


Adenovirus infection in children

Incubation period: Onset often sudden fever often spines, pharyngitis of the upper respiratory tract, nasopharyngitis, or pharyngitis, eye conjunctivitis and painful swelling of the lymph nodes in the neck (also called APC due to type 3 and 7 infection).

There may be a generalized maculopapular rash.

Adenovirus infection in adults

The main symptoms are high fever, cough, nasopharyngeal discharge, swelling of peripheral lymphadenitis and systemic maculopapular rash in some cases caused by types 4 and 7.

Other diseases caused by Adenovirus

Adenovirus can cause clinical illness outside the respiratory tract

Haemorrhagic cystitis: Due to infections of types 11 and 21:

Acute diarrhoea: Due to types 40, 41.

Conjunctivitis - corneal: caused by types 8, 9 and 37.


Clinical manifestations: Suspected Adenovirus infection in the presence of upper respiratory tract inflammation, accompanied by high fever, pharyngitis, eye conjunctivitis, lymphadenitis

Laboratory tests: Diagnosis is confirmed based on culture results, isolating virus from pharyngeal mucus, urine sputum or feces

Adenovirus type 40, 41 causing diarrhoea in children can be detected by ELISA Test or RIA with faecal sample

Determination of antibody titres by neutral complement combination reactions, ELISA or RIA, detect Adenovirus types causing erythrocyte agglutination by erythrocyte agglutination inhibitory reaction (HI).


The main symptomatic treatment is, antiviral drugs have not been used in clinical practice. Antibiotic treatment in case of bacterial superinfection


General prevention is similar to other acute respiratory viral infections.

Lethality reduction vaccines against types 4 and 7 have been used in recruiting camps.