Human Orthopneumovirus: Respiratory Syncytial Virus (RSV) Human RSV
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A common respiratory viral infection caused by a human orthopneumovirus: Respiratory syncytial virus (RSV) Human RSV Respiratory syncytial virus (RSV) was discovered in 1957 during an outbreak of a febrile RSV is highly contagious with respiratory illness within a colony of confined an incubation period of two to chimpanzees. Most of the chimpanzees eight days since contact with eventually recovered and developed antibodies an infected person. It’s to the illness. It was then discovered that the estimated that one infected source of their infection was not from an animal, person will transmit the virus but instead from a laboratory worker who to at least five others. acquired and transmitted the virus to the primates.1 Later in 1958, a febrile lower respiratory illness outbreak was reported involving The symptoms can persist for 27 infants and young children in a Washington DC welfare nursery along with one to two weeks. For eight additional infants in the area hospital.2 The virus was recognized as RSV immunocompromised and gained more attention within the medical community as a new, highly- individuals, symptoms and viral shedding can continue for contagious pathogen that primarily affected infants and young children. four weeks or longer. Today, RSV is recognized as one of the most common causes of childhood respiratory illness with Respiratory droplets. fever. Its effect is not limited to infants or children though, as it can reinfect throughout a person’s Gloves, mask, gown, and eye lifetime and becomes more protection. Disinfect surfaces dangerous in the elderly. thoroughly as the virus can survive for several hours on 1 | P a g e hard surfaces. In the United States, respiratory syncytial virus usually circulates during fall, winter, and spring. Currently, there is no effective vaccine to protect a person from this highly-contagious virus. It’s the second leading cause of death by lower respiratory infections worldwide. The “common cold” can be caused by several different families of viruses --- most present with rhinorrhea (runny nose), fever, cough, and fatigue. Respiratory syncytial virus (RSV) leads the pack as the most common single cause of respiratory hospitalization of infants.3 It is also the second greatest cause of lower respiratory infection mortality (death) worldwide, following Streptococcus pneumoniae.3 While the death rate is low in the United States and other developed countries, the hospital resource use is high, especially during the winter months.4 The immune system doesn’t have a strong response to reinfection. Respiratory syncytial virus is very contagious, and the immune response does not appear to develop a strong, prevailing response to reinfection. So, it’s common for children and adults to be reinfected with the virus throughout their lifetime. As the person enters their geriatric stage of life, this virus can increase their risk of death when combined with pre-existing medical conditions and aging body systems. There is no vaccine, yet. There is no effective vaccine for this virus.4 Previous vaccination attempts resulted in only a short duration immunity that was not highly effective. Decades ago, some of the early RSV vaccine candidates caused an increased inflammatory response in the inoculated infants and was quickly discontinued. This setback and decreased interest in funding (compared to influenza) delayed vaccine development for RSV. However, it’s anticipated that a safe, effective vaccine may be available within 5 to 10 years.4 2 | P a g e The effect on lung tissue is different compared to most other respiratory viruses. The name of the illness itself describes the injury pattern: Syncytial. Most cells in the body have one nucleus per cell. When this virus attacks lung tissue, it releases a protein that causes neighboring cells to bind and meld together. Eventually, the cells conjoin and become a large cell with multiple nucleases, as shown to the right. Organized syncytium formation is normal for cells interconnected by specialized membranes with gap junctions, as seen in the heart muscle cells and certain smooth muscle cells that synchronize electrically in an action potential. But when a random syncytium forms in lung tissue from individualized cells, it adversely affects gas exchange and cellular function. For most infants and children, this lung injury eventually heals on its own. In a few others, it could be fatal. Infants and young children infected with RSV usually present with cold-like symptoms that may include:5 • Cough (usually develops on day one to three) • Rhinorrhea (earliest sign accompanied with a loss of appetite) • Fever • Sneezing • Wheezing • Apnea in rare cases A few infants and children require hospitalization. Usually, they are younger than 6 months old and/or have other medical conditions such as prematurity, suppressed immune systems, lung or heart disease, or neurological disorders that lead to difficulty swallowing or clearing mucus secretions. 3 | P a g e Older children and young adults infected with RSV usually have mild or no symptoms. Symptoms are usually consistent with an upper respiratory tract infection and may include rhinorrhea, pharyngitis, cough, headache, fatigue, and fever. The RSV symptoms usually last less than five days.5 One of the most common conditions associated with RSV is bronchiolitis, which involves inflammation and congestion of the small airways (bronchioles) in the lung. Young age remains the greatest risk factor for bronchiolitis since infant and young children have: • Smaller diameter airways • Impaired respiratory capacity • And low respiratory reserve. The risk is greatest at one month of age and decreases as they get older.4 Normal bronchioles compared to inflamed from bronchiolitis. Image modified from: Barker (2014) 4 | P a g e Adults who are at high risk for severe illness from RSV include: 5 • Older adults, especially those 65 years and older • Adults with chronic lung or heart disease • Adults with weakened immune systems In older adults, age has already impacted the resiliency of lung tissue over the years, the immune system is less robust, and an RSV infection only worsens any pre-existing conditions. Respiratory syncytial virus can lead to an exacerbation of underlying conditions such as asthma, chronic obstructive pulmonary disease (COPD), or congestive heart failure.5 Respiratory syncytial virus is very contagious. Although it only survives about half an hour on hands and up to eight hours on hard, non-porous surfaces,6 its primary mechanism of infection is through respiratory droplets. Contact transmission is secondary. Respiratory syncytial virus is more contagious 5 than influenza; One person with RSV usually infects at least five others versus the 1:3 ratio for the flu. Secretions released when coughing, talking, or sneezing carry the virus and spread it to others directly or from touching hard surfaces like telephones, computers, and doorknobs. While those infected with RSV are contagious for 3 to 8 days, there are others who may shed the virus for up to four weeks --- usually young children with compromised immune systems. Through both the respiratory droplet and direct contact routes, there’s a greater risk of acquiring RSV in schools and daycares with shared items such as toys. Children also play and interact closely in groups. Nearly every child will experience at least one RSV infection before reaching their second year of age.7 While most children and young adults will only experience cold-like symptoms for about a week, children with a depressed immune system, effects from premature birth, lung or heart conditions may require hospitalization.5,7 For treatment, most infants, children, and adults only need supportive care. In infants particularly though, any changes in feeding, elimination (urine or fecal), or change in mental status while ill should be a warning sign to seek medical care.7 5 | P a g e For high-risk infants and young children, prevention is key. Besides hand washing and avoiding high-risk environments, there is a monthly intramuscular injection that may be given to high-risk infants and young children to help reduce the severity of symptoms during RSV season: Palivizumab (Synagis). This is a monoclonal antibody recommended by the American Academy of Pediatrics (AAP) to be administered to high-risk infants and young children under two years old who are likely to benefit from immunoprophylaxis based on gestational age and certain underlying medical conditions.5 It is not recommended for all infants and children. The most common side effect with palivizumab is a fever and rash. In the prehospital setting, physician evaluation is still recommended post-palivizumab use if there’s a rash and fever since this can also be a sign of a more serious condition in the child. For RSV, transmission is primarily through respiratory droplets. Gloves, gown, and a mask (surgical) encompassed the usual recommendation by the Centers for Disease Control and Prevention (CDC) prior to the SARS-CoV-2 (“COVID-19”) pandemic.8 Since RSV presents with similar symptoms as COVID-19, an N95, eye protection, gloves, and disposable gown or Tyvek suit remains the current recommendation to protect healthcare providers and prevent further transmission of any respiratory virus. Standard disinfectants labeled as effective viricides will kill RSV. This includes 70% isopropyl alcohol (“rubbing alcohol”) if allowed to dwell undisturbed on the surface for 3 to 5 minutes and other common disinfecting products. Hand washing for at least 20 seconds remains one of the primary ways to prevent transmission of the virus through direct contact. Be sure to complete the quiz and evaluation to earn credit for this education. Please let a member of the training staff know of any questions. Thank you! 6 | P a g e 1 Blount RE Jr, Morris JA, Savage RE. Recovery of cytopathogenic agent from chimpanzees with coryza. Proc Soc Exp Biol Med. 1956 Jul;92(3):544-9.