Which diagnostic test is necessary to confirm RSV infection?

Confirming respiratory syncytial virus (RSV) infection is best achieved through viral nasal washing combined with monoclonal antibody testing. This method allows for direct detection of the virus, which is crucial because RSV is a common viral pathogen that can lead to severe respiratory illness, particularly in infants and immunocompromised patients.

The technique involves collecting a sample from the nasopharynx, which may then be analyzed for the presence of RSV antigens. Monoclonal antibody tests are designed specifically to identify RSV proteins, providing a reliable and accurate confirmation of the infection. This approach is essential in a clinical setting as it guides management and informs isolation protocols during outbreaks.

Other methods, such as a CBC with differential or chest X-ray, may be useful in evaluating a patient's overall clinical condition or ruling out other potential causes of respiratory symptoms; however, they do not specifically confirm RSV infection. Similarly, pulmonary function tests are not relevant to diagnosing a viral respiratory infection like RSV and are typically utilized in the assessment of chronic lung conditions rather than acute viral illnesses. Thus, the choice of viral nasal washing with monoclonal antibody testing stands out as the definitive method for RSV diagnosis.