viral pneumonia



OVERVIEW

Definition

Viral pneumonia is interstitial and parenchymal inflammation of the lungs caused by viral invasion of human respiratory epithelial and alveolar epithelial cells. It often results from the downward spread of viral infections in the upper respiratory tract.

The most common viruses causing this type of pneumonia are influenza virus, followed by respiratory syncytial virus, adenovirus, parainfluenza virus, measles virus, herpes simplex virus, cytomegalovirus and coronavirus. Pneumonia caused by viruses other than influenza and parainfluenza viruses is most common in children and can be caused by one or more viral infections.

Types

Types according to clinical manifestations

Viral pneumonia can be categorized into mild and severe cases.

Types according to the causative virus

The main types are listed below.

Simply called syncytial virus pneumonia, it is the most common viral pneumonia. It is divided into two subtypes, A and B, with subtype A predominating in China.

The disease is most common in infants and young children, especially in children under 1 year old.

Adenovirus pneumonia is caused by adenovirus infection. There are 42 serotypes of adenovirus, and the most common ones causing pneumonia in children are 3 and 7.

The disease is most common in children aged 6 months to 2 years and occurs more often in winter and spring.

It is characterized by acute onset, prolonged high fever, severe toxicity, late onset of rales, early onset of X-ray changes compared with pulmonary signs, and easy to be combined with myocarditis and multiorgan dysfunction.

The population is generally susceptible to influenza viruses, and in children, infants and young children less than 2 years of age are particularly susceptible. Influenza virus pneumonia is more likely to occur during influenza epidemics.

Infants and young children, especially those younger than 2 years of age, have significant respiratory symptoms, wheezing, and in severe cases, respiratory failure and heart failure.

Combined or secondary bacterial infections are very common, with Streptococcus pneumoniae, Haemophilus influenzae and Staphylococcus aureus being the most common pathogens. School-age children are prone to Mycoplasma infections.

All types of coronaviruses can infect the lung parenchyma, most of which are mild, with 2 newly identified types that are more severe, the severe acute respiratory syndrome coronavirus (SRAS-CoV, also known as SARS virus) and the novel coronavirus (COVID-19).

Morbidity

Viral pneumonia occurs most often in winter and spring and can be disseminated in epidemics or outbreaks.

Viral infections account for 25% to 50% of non-bacterial pneumonia.

The majority of patients are children; adults are relatively uncommon.

Upper respiratory tract infections caused by adenovirus are common, of which 80% occur within the first 7 to 24 months of life. 10% of neonatal viral pneumonias are adenovirus infections.

Causes

Causes

Viral pneumonia is mainly caused by viral infections.

Causative viruses

Influenza virus is the most common, and other viruses include parainfluenza virus, cytomegalovirus, adenovirus, rhinovirus, coronavirus, and certain enteroviruses, such as coxsackie virus, echovirus, etc., as well as herpes simplex virus, varicella zoster virus, rubella virus, measles virus, and so on.

It is often caused by respiratory syncytial virus infection in infants and young children.

Sources of infection

The main source of infection is patients or carriers of the virus.

Route of transmission

Droplet transmission: patients or virus carriers sneeze, cough, etc. to produce droplets, inhalation with the virus and be infected.

Contact transmission: contact with secretions carrying the virus, and then the secretions enter the respiratory tract and cause infection.

Fecal-oral route of transmission: the infection is seen in enterovirus.

Dustborne transmission: Respiratory syncytial virus is often transmitted through dust.

Other routes of transmission: Transplant recipients may become infected due to the presence of the virus in the donor’s organ.

Pathogenesis

The pathogenesis of viral pneumonia is not clear. It may be caused by a virus that infects the upper respiratory tract of the human body. When the resistance of the infected person is lowered or the virus is highly virulent, the virus enters the lower respiratory tract and causes infection, resulting in viral pneumonia.

Symptoms

Main Symptoms

Fever

Headache.

Generalized soreness and tiredness.

Cough with small amount of sputum or white mucus sputum.

Sore throat.

Other symptoms

There may be dyspnea, cyanosis, drowsiness, and depression. In severe cases, respiratory distress syndrome may occur with severe dyspnea.

In some patients with immunodeficiency, the condition is more severe with persistent high fever, palpitations, shortness of breath, cyanosis, and shock.

Complications

Lung abscess: there may be chills, high fever, cough and sputum, etc. With the progression of the disease, there may also be bloody sputum, lethargy and fatigue.

Abscessed chest: in case of chronic abscessed chest, there are often emaciation, fatigue, poor appetite, anemia, etc. Acute abscessed chest may have shortness of breath, rapid heartbeat, generalized fatigue and other manifestations.

Multi-organ failure: Infectious shock, heart failure, respiratory failure and acute respiratory distress syndrome may occur in severe patients, and there may be coma, shortness of breath, edema, severe hypoxia and other manifestations.

Consultation

Department of Medicine

Respiratory Medicine

When symptoms such as fever, cough and sputum appear, timely consultation is recommended.

Emergency Department

If there is an emergency such as high fever or difficulty in breathing, it is recommended to go to the Emergency Department immediately.

Preparation for medical treatment

Information on how to get to the doctor: registration, preparation of documents, and common problems.

Tips for seeking medical treatment

Chest X-rays or chest CTs are often needed, so avoid wearing clothing made of metal. Those who are pregnant or planning to become pregnant should inform the doctor.

Avoid taking fever-reducing medicines or antibiotics by yourself before going to the doctor, so as not to influence the doctor’s judgment of the condition. For patients with high fever, physical cooling can be used first, such as applying cold compresses to the forehead and wiping the hands, feet and armpits with lukewarm water.

Preparation checklist for medical consultation

Especially need to pay attention to the time of symptom onset, special performance, etc.

Is there fever? What is the highest temperature?

Is there a cough? How long has the cough lasted?

Is there any sputum? What kind of sputum?

How long have the symptoms been present?

Have you had a cold recently?

Have you been in contact with anyone who has had a cold or pneumonia?

Test results in the last 6 months, which can be brought to the doctor’s office

Laboratory tests: blood test, respiratory virus nucleic acid test, respiratory virus antibody test

Imaging tests: Chest X-ray, Chest CT scan

Medication in the last 3 months, if available, bring along the box or package with you.

Antiviral drugs: oseltamivir, acyclovir, ganciclovir

Antipyretics: ibuprofen, acetaminophen

Diagnosis

Diagnosis is based on

Medical history

History of colds, etc.

Clinical manifestations

Mild cases may have no obvious signs and symptoms.

In more severe cases, there are systemic manifestations such as fever, headache, generalized aches and pains, tiredness, etc., as well as respiratory manifestations such as cough, little sputum or white mucous sputum, and sore throat. Some patients present with persistent high fever.

Dry and wet rales, rales, sputum sounds and signs of pulmonary solid changes appear in the lungs. In severe cases, dyspnea occurs.

Extrapulmonary damage and even multiple organ failure may occur in very severe cases.

Laboratory Tests

White blood cell count and lymphocyte count are checked.

Usually the white blood cell count is normal and the lymphocyte count may be slightly elevated. In combination with bacterial infection, the white blood cell count is increased.

Polymerase Chain Reaction (PCR) test can detect the nucleic acid of the virus and is valuable in confirming the diagnosis of new mutated viruses and rare viruses. It helps to make an early diagnosis.

If specific IgM antibodies are present it can be assumed that there is a recent infection.

If IgG is elevated more than 4-fold, it helps to make an early diagnosis.

Imaging

Examines the lungs and other organs of the chest.

Lung images may be abnormal in viral pneumonia.

Precautions

Differential diagnosis

Colds

Similarities: both have cough, headache, sore throat.

Differences: Colds do not present with white mucus sputum, cyanosis, and dyspnea. It can be differentiated by chest X-ray or CT examination.

Mycoplasma pneumonia

Similarities: both have fever, headache, sore throat, cough.

Differences: Mycoplasma pneumonia is characterized by an irritating dry cough with little or no sputum, and a few cases may have maculopapular rash or erythema. Differentiation is made by pathogenetic examination.

Bacterial pneumonia

Similarities: headache, chest pain, generalized weakness, fever.

Differences: Bacterial pneumonia may have purulent sputum and chest pain radiating to the shoulders or abdomen. Differentiate by pathogenetic examination.

Treatment

General treatment

Bed rest.

Keep indoor air circulation, pay attention to isolation and sterilization.

Supplement vitamins and proteins, such as fresh fruits and vegetables, eggs and milk. Eat small amount of food several times.

Drink plenty of water.

Promote the discharge of phlegm and keep the respiratory tract unobstructed.

Medication

Commonly used antiviral drugs include ribavirin, acyclovir, ganciclovir, oseltamivir, adenosine, amantadine and so on.

If there is a combination of bacterial infection, antibacterial drugs will be used at the same time.

Supportive therapy

Critically ill patients need cardiac monitoring, along with oxygen or mechanical ventilation, correction of hypoxemia, vital organ function support, blood purification and other treatments.

Traditional Chinese Medicine (TCM)

The main function of Chinese medicine treatment is to clear the lungs, dissolve phlegm and calm asthma, which can be realized by taking Chinese medicine soup.

TCM treatment should be carried out in a professional and qualified organization.

Prognosis

Cure

The treatment outcome of viral pneumonia is related to the type of virus infecting the patient, and most of them can be cured on their own.

Harmfulness

When viral pneumonia is severe, it can cause complications such as shock, heart failure, respiratory failure and acute respiratory distress syndrome.

It has a high mortality rate if infected with a new variant of the virus and is also prone to secondary infections such as bacteria.

Daily

Daily Management

Dietary management

Maintain nutritional balance and ensure adequate intake of various nutrients.

Exercise management

After rehabilitation, exercise with light activity such as walking, jogging and tai chi can be chosen appropriately.

Lifestyle Management

Avoid second-hand smoke and prohibit smoking.

Maintain personal hygiene.

Maintain a regular routine and get enough rest.

Maintain a good indoor environment.

Maintain a happy mood.

Avoid other pathogens.

For mild cases, home isolation should be observed and treated.

Follow-up

Regular follow-up and chest X-ray and CT examination.

If symptoms worsen or do not resolve, consult a doctor promptly.

Prevention

A good lifestyle is helpful in preventing viral pneumonia.

Appropriate exercise and keeping warm can strengthen body resistance and prevent viral infections.

If you have immunodeficiency diseases, treat them aggressively.

During periods of high influenza outbreaks, go out as little as possible and avoid crowded places.

Pay attention to personal hygiene and wash hands frequently.

Items used by the patient should be sterilized.