Respiratory Viral Infections in Adults
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Direct answer
Respiratory viral infections in adults are most often caused by rhinoviruses (influenza and SARS-CoV-2 are covered separately), but RSV, adenovirus and parainfluenza viruses matter because they cause lower respiratory disease in the elderly, the immunocompromised and people with chronic lung disease. Most infections are self-limiting and managed with supportive care. Secondary bacterial pneumonia, exacerbation of asthma or COPD, and ARDS are the main complications to watch for.
What you must remember
- Rhinovirus: the commonest cause of the common cold, and an important trigger of asthma and COPD exacerbations in adults.
- RSV: causes bronchiolitis in infants, but in adults it mainly affects the elderly and immunocompromised, producing lower respiratory disease and worsening heart and lung disease.
- Adenovirus: causes pharyngoconjunctival fever, and types such as 7 and 14 are associated with severe pneumonia in crowded settings.
- Parainfluenza: types 1 and 2 cause croup in children, while in adults it is usually a mild upper respiratory illness, with significant disease in transplant recipients.
- Secondary bacterial pneumonia: Streptococcus pneumoniae and Staphylococcus aureus can follow viral infection, especially after a period of initial improvement.
- Diagnosis: multiplex PCR on respiratory samples identifies several viruses at once, while rapid antigen tests are less sensitive.
- Treatment: supportive care, with antivirals such as ribavirin or cidofovir used selectively in severe or immunocompromised disease, and oseltamivir not active against these viruses.
Where the exam tries to catch you
Examiners test whether the student matches the virus to the disease it causes and remembers the bacterial complication. The traps below are the most common errors in this area.
- Trap: oseltamivir for an adult with severe RSV infection Correct: oseltamivir treats influenza, not RSV, adenovirus or rhinovirus.
- Trap: rhinovirus causes the most severe adult pneumonias Correct: rhinovirus usually causes mild colds, while RSV and adenovirus are more likely to cause lower respiratory disease.
- Trap: a worsening patient with viral pneumonia has only viral disease Correct: secondary bacterial pneumonia often follows, so reassessment for superinfection is needed.
Frequently asked questions
Which respiratory virus causes severe pneumonia in adults?
RSV, adenovirus and parainfluenza viruses can cause severe lower respiratory disease in adults, particularly the elderly, transplant recipients and immunocompromised patients. Adenovirus types 7 and 14 are especially associated with severe pneumonia.
Why does rhinovirus matter in adults with asthma or COPD?
Rhinovirus is a common trigger of asthma and COPD exacerbations in adults, causing airway inflammation and worsening breathlessness. Respiratory viral infections in adults with chronic airway disease therefore warrant closer monitoring of breathlessness and oxygenation.
Is oseltamivir used for RSV or adenovirus infection in adults?
Oseltamivir is not used for RSV or adenovirus infection because it is an antiviral for influenza. These infections are managed with supportive care, and selected antivirals such as ribavirin or cidofovir are used only in severe or immunocompromised disease.
What is the test of choice for identifying respiratory viruses in adults?
Multiplex PCR on respiratory samples is the test of choice for identifying several respiratory viruses in adults at once. Rapid antigen tests are less sensitive, so a negative result does not reliably exclude a viral infection.
What is a major complication of viral respiratory infection in adults?
Secondary bacterial pneumonia, often from Streptococcus pneumoniae or Staphylococcus aureus, is a major complication of viral respiratory infection in adults. Exacerbation of asthma or COPD is another frequent complication, and worsening after initial improvement should prompt review.