The WHO estimates that respiratory syncytial virus (RSV) is the most common respiratory infection in children, with approximately 34 million yearly cases. Middle- and low-income countries suffer over 90% of all RSV-related deaths. Most children are estimated by the Centers for Disease Control and Prevention (CDC) to have had the virus by the time they have reached 2 years old. Symptoms include a runny nose, wheezing, fever, sneezing, and decreased appetite. Like many other viruses, RSV can survive on surfaces and be spread through close contact with those with the illness. RSV is generally contagious for 3–8 days, but those with a weakened immune system may shed the virus for up to 4 weeks. RSV infections can also occur in adults, but the symptoms are usually milder; however, severe infections can occur in older adults and those with weakened immune systems. There are indications of possible interference between respiratory viruses as yearly peaks of RSV and influenza occur at different times during the winter.
Like influenza, RSV is an enveloped single-stranded RNA virus that belongs to the Pneumoviridae family. The virus is approximately 150–300 nm in diameter. It contains F (fusion) and G (glycoprotein) proteins on its surface. These proteins are used to attach to the host cell. F and G proteins can illicit host antibody reactions. The virus contains M (matrix) protein and three other nonstructural proteins.
