Respiratory Syncytial Virus or RSV is the most common cause of acute respiratory infections in infants and young children. It is responsible for more than 60% of lower respiratory tract infections, such as bronchiolitis (inflammation of the small airways) and pneumonia, in children less than 4 years of age worldwide. 80% of these infections are in infants with peak occurrence between the ages of 2 and 8 months. By the age of 3, most children have had at least 1 RSV infection. Although infants and children are primarily affected, it also affects the elderly and is responsible for 177,000 hospitalizations and 14,000 deaths in adults aged 65 and older.
What Does the RSV Molecule Look Like?RSV is composed of 11 proteins with an envelope around it. The envelope has glycoproteins G and F (fusion) that attach to the cells in the respiratory system and airways.
Is There a Season for RSV?
RSV is seen beginning from mid-September to mid-November, with peak from mid-December to mid-February. In the southern United States, it can be seen throughout the year with peak occurrence from August to September.
What are the Risk Factors?
Risk factors associated with RSV infection include crowded living conditions, minimal to absent breastfeeding, immunosuppression, children with chronic lung disease and congenital heart defects, and infants born prematurely. In-hospital mortality is generally less than 1 % but can be 3-5% in children with underlying chronic lung and heart disease. RSV can also be severe in adults with COPD and in those over 65 years of age.
What Tests are Needed to Confirm RSV?
Secretions from the nasopharynx in symptomatic individuals can be tested for RSV by culture, antigen detection testing, or polymerase chain reaction (PCR) test. In asymptomatic persons, an increase in IgG antibody titer to RSV antigen, by a factor of four of more is diagnostic. PCR testing has high sensitivity of 100% and specificity of 89%. Although not specific to RSV, chest x-ray is often done for infants with severe RSV infection to evaluate for pneumonia.
What are the Clinical Signs & Symptoms of RSV?
There is an incubation period of 3-5 days between exposure to RSV and development of symptoms. Symptoms then begin with involvement of the upper respiratory tract (nasal congestion, sneezing) followed by spread to the lower respiratory tract, resulting in bronchiolitis, and pneumonia. There is increased work of breathing, cough with mucus production and wheezing, Studies have also shown a link between early childhood RSV infection and the development of asthma.
How do we Manage RSV Infection?
RSV is transmitted by contact with infected secretions and respiratory droplets. Transmission can be prevented by hand washing and cleaning surfaces. Once infection is acquired, management of RSV is mainly supportive, that is, fluids for hydration, supplemental oxygen when needed and managing respiratory secretions. Palivizumab is a monoclonal antibody against RSV. This is approved for RSV prophylaxis in premature infants with chronic lung disease less than 6 months of age and infants with congenital heart disease less than 24 months of age, at start of RSV season. It has been shown to reduce hospitalizations and improve symptoms of wheezing in this high-risk infant group.Clinical Trials
At Chase Medical Research, a vaccine trial targeting RSV in adults will soon be underway. If you are interested in participating in this trial or any one of our other enrolling trials, don't hesitate to check out our website for currently enrolling trials.
For more information on RSV, please click here.
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Krilov, Leonard R., Steele, Russell W. February 25, 2019. Respiratory Syncytial Virus Infection. Medscape.com/article/971488.
Piedmonte, Giovanni. November 2015. RSV infections: State of the art. Cleveland Clinic Journal of Medicine. Volume 82.