How is Respiratory Syncytial Virus (RSV) infection diagnosed and managed in adults?

Diagnosis of RSV Infection in Adults

Diagnose RSV infection in adults using nucleic acid amplification testing (NAAT/RT-PCR) from nasopharyngeal swabs or nasal aspirates, as this is the most sensitive diagnostic method, particularly important given that rapid antigen tests and viral culture perform poorly in adults due to lower viral loads. 1

Diagnostic Testing Methods

Preferred Diagnostic Approach

• NAAT/RT-PCR is the gold standard for RSV diagnosis in adults, offering superior sensitivity compared to other methods 1, 2
• Obtain specimens from nasopharyngeal swabs, nasal aspirates, nasal washes, or throat swabs 1, 3
• For immunocompromised adults with suspected lower respiratory tract infection, test lower respiratory specimens (BAL fluid, endotracheal aspirate) as these are significantly more sensitive than upper respiratory samples (BAL: 88.9% vs. nasal wash: 15%) 1

Available Testing Platforms

Multiple testing options exist, listed from most to least comprehensive 1:

• Multiplex PCR panels detecting influenza, RSV, and other respiratory viruses plus atypical bacteria (e.g., FilmArray Pneumonia Panel, ePlex Respiratory Pathogen Panel)
• Multiplex PCR for respiratory viruses only (>4 targets)
• Targeted multiplex PCR for influenza A/B plus RSV (e.g., Xpert Flu/RSV XC)
• Single-target RSV assays (e.g., Alere I RSV)

Alternative Diagnostic Methods (Less Sensitive)

• Rapid antigen detection tests have poor sensitivity in adults (40-80% for influenza, likely similar for RSV) due to lower viral loads compared to children 1
• Direct fluorescent antibody staining can be used but has lower sensitivity than NAAT 1
• Viral culture is too slow for clinical decision-making (results take days to weeks) and has poor sensitivity in adults 1, 4
• Serology is NOT recommended for acute diagnosis as high seroprevalence indicates past exposure; it is only useful for epidemiological studies 1, 5

When to Test for RSV

Clinical Indications

Test adults presenting with 3:

• New onset respiratory symptoms: cough (present in 93% of cases), nasal congestion/discharge, shortness of breath, or sore throat
• Symptoms occurring during RSV season (typically December-March in Northern Hemisphere)
• Known community outbreaks or epidemiological link to infected contacts

High-Priority Populations Requiring Testing

Always test these high-risk groups 3, 2:

• Elderly patients ≥65 years (especially ≥75 years)
• Patients with chronic cardiac or pulmonary disease (COPD, asthma, heart failure)
• Immunocompromised individuals (solid organ or hematopoietic stem cell transplant recipients, hematological malignancies, HIV infection, chronic immunosuppressive therapy)
• Residents of long-term care facilities
• Hospitalized patients with acute cardiopulmonary conditions

Outbreak Settings

• During suspected respiratory viral outbreaks in long-term care facilities, obtain nasopharyngeal samples from several acutely ill residents for virus isolation and rapid diagnostic testing 1
• Testing helps guide isolation precautions and outbreak management, reducing hospitalization costs and outbreak duration 1

Clinical Presentation Considerations

Distinguishing Features (Though Not Diagnostic)

RSV infection in adults typically presents with 4, 2, 6:

• Nasal congestion, cough, wheezing, and low-grade fever
• Patients hospitalized with RSV are typically older with more comorbidities and respiratory symptoms but frequently WITHOUT fever compared to influenza patients
• Clinical features overlap significantly with other respiratory viruses, making laboratory confirmation essential 1, 5

Disease Severity Indicators

RSV accounts for 1, 2, 7:

• 4-11% of adults hospitalized with respiratory tract infections
• 6-15% of hospitalized RSV patients require intensive care admission
• 1-12% mortality among hospitalized adults with RSV
• Similar disease burden to non-pandemic influenza in elderly populations

Critical Diagnostic Pitfalls to Avoid

• Do not rely on clinical features alone to distinguish RSV from influenza or other viral infections—laboratory confirmation is essential 1, 2
• Do not use single upper respiratory tract specimens in critically ill or immunocompromised patients—test lower respiratory specimens for higher sensitivity 1
• Do not accept negative rapid antigen tests as definitive—confirm with NAAT if clinical suspicion remains high 1
• Do not delay testing in high-risk populations—early diagnosis impacts isolation decisions and potential treatment in immunocompromised patients 1, 3