Most commonly found in kids, the virus remains the single most leading cause of hospitalization in infants for respiratory problems.
Reinfection may happen throughout one’s lifetime with infection rates typically higher during the cold winter months, which can cause bronchiolitis in infants, common colds in adults and more serious respiratory illnesses such as pneumonia in the elderly and immunocompromised.
Several tests exist to diagnose RSV, such as viral culture, serology, antigen detection tests and nucleic acid amplification tests (NAATs). Conventional polymerase chain reaction (PCR) and nested PCR are considered to be simple and economical in a laboratory setting.
Tests for RSV
Samples are collected from the nasopharynx, saliva or, sometimes, blood (for antibody detection), and used in the following tests:
Antigen detection test
- Antigen detection assays include:
- Direct immunofluorescence assays (DFA)
- Enzyme immunosorbent assays (EIA)
- Chromatographic and optical immunoassays
- The DFA uses fluorescein-labeled antibodies that detect respiratory syncytial virus (RSV) antigen in epithelial cells in respiratory secretions. It has the advantage that the immunofluorescence pattern of the infected cells can be directly examined by microscopy, which gives an additional confirmation of specificity.
Virus isolation in tissue culture
- Isolation of RSV in tissue culture was considered the gold standard for confirmation of the disease. The advantage of this tissue culture technique is that it is more sensitive than rapid antigen detection kits, and provides the ability of further antigenic and genetic characterization of the amplified virus.
Nucleic acid tests (NATs)
- Nucleic acid assays have revolutionized the diagnostic procedures in virology and are the most sensitive and specific methods for the detection of RSV. Of the different nucleic acid amplification techniques, reverse transcription polymerase chain reaction (RT-PCR) is the first and most frequently used nucleic acid-based assay.
How does RSV spread?
Respiratory syncytial virus (RSV) is highly contagious and spreads through droplet transmission. When a person with the infection coughs or sneezes, secretions from their respiratory tract containing the virus spreads in the air.
Following transmission through the nose or eyes, RSV infects cells lining the upper and lower airway and continues to replicate within these bronchial cells for about eight days. After the first several days, RSV-infected cells slough into the smaller bronchioles of the lower airway. This sloughing mechanism is also thought to be responsible for the spread of the virus from the upper to the lower respiratory tract.
The infection causes generalized inflammation within the lungs, including the migration and infiltration of inflammatory cells (such as monocytes and T-cells), necrosis of the epithelial cell wall, edema and increased mucous production. Inflammation and cell damage tend to be patchy rather than diffuse. Together, the sloughed epithelial cells, mucous plugs and accumulated immune cells obstruct the lower airway.
What are the complications of RSV?
Complications of respiratory syncytial virus include:
- Hospitalization. A severe respiratory syncytial virus (RSV) infection may require a hospital stay so that doctors can monitor and treat breathing problems and give intravenous (IV) fluids.
- Pneumonia. RSV is the most common cause of inflammation of the lungs (pneumonia) or the lungs’ airways (bronchiolitis) in infants. These complications can occur when the virus spreads to the lower respiratory tract. Lung inflammation can be quite serious in infants, young children, older adults, immunocompromised individuals or people with chronic heart or lung disease.
- Middle ear infection. Germs that enter the space behind the eardrum can lead to otitis media (middle ear infection). This happens most frequently in babies and young children.
- Asthma. A link may exist between severe RSV in children and the chance of developing asthma later in life.
- Repeated infections. There is also the chance of reinfection from the same virus after recovery, which is even possible during the same RSV season. Though symptoms usually aren’t as severe, typically in the form of a common cold, they can be serious in older adults or people with chronic heart or lung disease.
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