respiratory syncytial virus

respiratory syncytial virus
Name	Respiratory Syncytial Virus
Synonyms	RSV
Field	Infectious disease (medical specialty), Pediatrics, Pulmonology
Symptoms	Rhinorrhea, Cough, Fever, Wheezing
Complications	Bronchiolitis, Pneumonia, Apnea
Duration	1–2 weeks
Causes	Infection by respiratory syncytial virus
Risks	Premature birth, Congenital heart disease, Chronic lung disease
Diagnosis	Reverse transcription polymerase chain reaction, Rapid antigen test, Nasopharyngeal swab
Prevention	Nirsevimab, Palivizumab, RSVpreF vaccine
Treatment	Supportive care, Oxygen therapy, Mechanical ventilation
Medication	Ribavirin (rarely)
Frequency	Annual epidemics in temperate regions
Deaths	~100,000 annually in children <5 globally

respiratory syncytial virus is a ubiquitous and highly contagious pathogen that is a leading cause of lower respiratory tract infections in infants and young children worldwide. It was first isolated in 1956 from a chimpanzee with coryza by Robert M. Chanock and colleagues at the National Institutes of Health. The virus causes annual epidemics in temperate climates, typically during the Winter and early Spring, placing a significant burden on healthcare systems like the National Health Service and the Centers for Disease Control and Prevention.

Virology

This pathogen is an enveloped, negative-sense, single-stranded RNA virus belonging to the family Pneumoviridae and genus Orthopneumovirus. Its genome encodes for several key proteins, including the Fusion protein and Glycoprotein which mediate host cell entry and are primary targets for prophylactic monoclonal antibodies such as Palivizumab. The viral RNA polymerase is error-prone, contributing to antigenic variation that challenges long-term immunity. Research into its structure and replication cycle has been advanced by institutions like the World Health Organization and the National Institute of Allergy and Infectious Diseases.

Signs and symptoms

Following an incubation period of about four to six days, initial symptoms often mimic the Common cold, including Rhinorrhea, Pharyngitis, mild Cough, and low-grade Fever. In severe cases, particularly in high-risk infants, the infection progresses to the lower airways, manifesting as Bronchiolitis or Pneumonia, with signs like Tachypnea, Wheezing, Crackles, and Cyanosis. Severe disease can lead to Respiratory failure, necessitating admission to a Pediatric intensive care unit, and may be complicated by Apnea, especially in very young infants. Otitis media is a common co-infection.

Transmission

The primary mode of spread is through direct or indirect contact with infectious respiratory secretions, making settings like Day care centers and Hospital wards high-risk environments. The virus can survive for several hours on hard surfaces such as Crib rails and Toys. Large-particle Aerosols generated by Coughing or Sneezing can also transmit the pathogen over short distances. Individuals are typically contagious for three to eight days, though immunocompromised patients, such as those undergoing Bone marrow transplantation, may shed the virus for weeks.

Diagnosis

Clinical diagnosis is common during community outbreaks, but laboratory confirmation is essential for infection control and cohorting patients in Hospitals. The gold standard test is Reverse transcription polymerase chain reaction on a Nasopharyngeal swab or aspirate, offering high sensitivity and specificity. Rapid antigen tests, often used in Emergency department settings like those in Johns Hopkins Hospital, provide quicker results but are less sensitive in adults. Chest X-ray findings, such as Hyperinflation and Peribronchial thickening, can support the diagnosis but are not specific.

Prevention

Prophylaxis for high-risk infants has historically relied on the monoclonal antibody Palivizumab, administered as monthly injections during the RSV season. A major advancement is the long-acting monoclonal antibody Nirsevimab, recommended by the Advisory Committee on Immunization Practices. For older adults, vaccines such as RSVpreF vaccine (Arexvy) from GlaxoSmithKline and Moderna's mRNA-based candidate offer protection. General measures include strict Hand hygiene, avoiding contact with sick individuals, and in Hospitals, implementing Contact precautions and Droplet precautions.

Treatment

Management is primarily Supportive care, focusing on maintaining Oxygenation and Hydration. This may involve Oxygen therapy via Nasal cannula or High-flow nasal cannula, and in severe cases, Mechanical ventilation in a Pediatric intensive care unit. The antiviral Ribavirin is rarely used due to marginal benefit and potential toxicity, though it may be considered for severely immunocompromised hosts. Bronchodilators like Albuterol are sometimes trialed but are not routinely recommended. Research into novel antivirals is ongoing, supported by entities like the Biomedical Advanced Research and Development Authority.

Epidemiology

This virus is a global pathogen, with an estimated 33 million annual lower respiratory tract infections in children under five, leading to approximately 100,000 deaths, with the majority occurring in low-income countries. In the United States, it causes about 58,000 hospitalizations annually in children under five. It is also a significant cause of morbidity and mortality in older adults, particularly those with Chronic obstructive pulmonary disease or Congestive heart failure. Surveillance networks like the National Respiratory and Enteric Virus Surveillance System track its seasonal activity, which in the Northern Hemisphere typically peaks between December and February.

Category:Infectious diseases Category:Pediatrics Category:Virology