Viral Pneumonia: What It Is, Symptoms, and Diagnosis

Viral pneumonia is inflammation of the lungs in which the cause of impaired gas exchange at the alveolar level is a virus or the body's immune response to it. It sounds alarming, but in most cases this type of pneumonia is mild and resolves on its own. Let's look at how to recognize it, how it differs from bacterial pneumonia, and which tests help confirm the diagnosis.

What viral pneumonia is

Viral pneumonia is an infection of the alveoli that causes the alveolar space to become clogged with fluid from exudate, damaged cells, and activated macrophages. Oxygen absorption decreases, and carbon dioxide begins to accumulate in the body. Viruses are one of the two leading causes of pneumonia, along with bacterial infection. In children, viral infection is the most common cause of pneumonia, whereas in adults the bacterial or mixed viral-bacterial nature is more common. Young children and older adults are affected more often.

Which viruses cause lung inflammation

The most common causes are influenza A and B viruses and respiratory syncytial virus. Less commonly, pneumonia is caused by parainfluenza viruses, adenoviruses, metapneumovirus, and coronaviruses SARS-CoV, MERS-CoV, and SARS-CoV-2. Certain viruses lead to pneumonia only in special cases: herpes simplex virus in newborns, varicella-zoster virus, cytomegalovirus in immunocompromised people, and measles and rubella viruses. The virus multiplies in lung cells, and tissue damage is largely related to the immune response: lymphocytes activate cytokines, which causes fluid to accumulate in the alveoli.

Symptoms of viral pneumonia in adults

Symptoms of viral pneumonia are often similar to those of an acute respiratory viral infection or influenza. These include fever, dry cough, runny nose, chills, muscle pain, headache, and increasing shortness of breath. Nausea, vomiting, and diarrhea are possible — signs of general intoxication. Wheezing is more often observed with viral infections. Early manifestations include headache, worsening shortness of breath, weakness, and worsening cough. In people with weakened immunity and in older adults, symptoms may be milder and sparse, up to low-grade fever, weakness, or sudden confusion.

Viral and bacterial pneumonia: what the difference is

The symptoms of both forms are similar, but with viral pneumonia they may be more varied. Bacterial pneumonia often develops on its own or after a viral infection such as a cold or influenza. With viral pneumonia, there is a risk of a secondary bacterial infection — usually caused by Staphylococcus aureus, pneumococcus, and Haemophilus influenzae — and this significantly worsens the course. That is why the doctor needs to determine the nature of the inflammation: this determines whether antibiotics, which do not act on viruses, are needed.

Diagnosis of viral pneumonia

Pneumonia can be difficult to recognize: it produces some of the same symptoms as a cold or influenza. The doctor takes a medical history and complaints, performs an examination, and listens to the lungs with a stethoscope. Further tests may be ordered:

• chest X-ray;
• blood tests, such as a complete blood count, to see whether the immune system is actively fighting the infection;
• blood culture — to identify a bacterial infection that has spread into the bloodstream;
• pulse oximetry — a check of blood oxygen levels;
• computed tomography of the chest to assess the extent of lung damage and complications.

In the hospital, for severe symptoms, sputum analysis, pleural fluid culture, and bronchoscopy are added.

Complications and when to see a doctor

Sometimes pneumonia causes serious complications: bacteremia with the risk of septic shock, lung abscesses, pleural damage, and renal and respiratory failure. Most people recover within 2–4 weeks; with a mild viral form, improvement occurs after 1–3 weeks. You should see a doctor if the cough persists for up to 3 weeks, yellow or green sputum appears, chest pain occurs when breathing or coughing, or shortness of breath develops.

Lung inflammation by itself is not a reason to call an ambulance; call 103 or 112 if the person is gasping for air, cannot speak, is gasping for breath, has pale, blue, or mottled skin, lips, or tongue, is coughing up blood, suddenly becomes disoriented, or cannot be woken up.

This material is for reference and does not replace a doctor's consultation — if in doubt, it is better to see a specialist than to wait for it to resolve on its own.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer