Respiratory Infections & Diagnosis
Respiratory tract infections are the leading cause of death amongst all infectious diseases and a wide range of organisms can cause respiratory infections including viruses, bacteria, fungi and parasites.
Respiratory tract infections are divided in lower respiratory tract infections (LRIs) and upper respiratory infections (URTIs). Influenza virus, RSV, parainfluenza virus, and adenovirus are the most common viruses that cause LRIs, although influenza can affect both the upper and lower respiratory tracts, and the more dangerous strains such as H5N1 tend to bind to receptors deep in the lungs. Young children, the elderly, and patients with compromised cardiac, pulmonary, or immune systems are at greatest risk for serious disease by respiratory pathogens. In children, 15%- 25% of pneumonias are caused by RSV, 15% by parainfluenza virus, and 7%- 9% by adenovirus. RSV infection is the most frequent cause of hospitalization in children under 5 years of age. In the elderly, respiratory viral infections cause up to 26% of hospital admissions for community-acquired pneumonia. Given is it not possible to accurately identify the causative organism based on clinical symptoms alone, diagnostic testing is typically required. It allows a clinician to effectively treat the infection and control its spread, since each organism (e.g. bacteria vs. viruses) does not respond to the same treatment (e.g. antibiotics). Diagnostic Testing – Immunoassays & Molecular Diagnostics Early detection of a respiratory infection is critically important to improve individual patient outcomes and to prevent the spread of the disease. It has been suggested that rapid testing for respiratory viruses, if established as the standard of care, could substantially lower health care costs and potentially save lives. Two main categories of diagnostic techniques that have emerged over years are (1) the detection of viral antigens by enzyme based immunoassays (EIAs) and (2) nucleic acid-amplification assays such as polymerase chain reaction (PCR). Commercially available EIAs include immunofluorescence (IFA) assays, ELISA and lateral flow assays which rely on monoclonal antibodies to directly detect the presence of the pathogen . Rapid molecular assays are available that detect the DNA or RNA of a pathogen and are generally higher in sensitivity and high specificity however require more specialized equipment and trained personnel. With the discovery of six new respiratory viruses since 2000, laboratories are faced with the challenge of detecting up to 19 different viruses that cause acute respiratory disease of both the upper and lower respiratory tracts. The application multi-analyte respiratory pathogen panels have been developed for both immunoassays and nucleic acid-amplification platforms that simultaneously broaden and streamline respiratory diagnostic testing. These panels typically include clinically important respiratory tract infections such as influenza A and B, RSV and parainfluenza 1,2 and 3 viruses, in a single swab test at the point-of- care. Numerous studies have demonstrated the improved sensitivity and specificity, broader pathogen coverage, and shortened turnaround time for these tests as compared to standard methods.
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Respiratory Diseases- Reagents for Assay Development
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