Understanding Respiratory Syncytial Virus (RSV)

Respiratory syncytial virus (RSV) is an RNA virus belonging to the Pneumoviridae family. It spreads through respiratory droplets, close contact, or contaminated surfaces and hands. Infection typically causes upper respiratory tract symptoms.

I. Basic Information

Classification: Pneumoviridae family, genus Pneumovirus

Primary Risk Group: Infants under 6 months

RSV pneumonia is a common interstitial pneumonia in children, particularly affecting infants and young children. Maternal antibodies do not prevent infection, allowing infections to occur shortly after birth, though it's less common in newborns. International reports occasionally document nosocomial outbreaks in hospital maternity wards.

II. Morphology

The virus is spherical, 120-300nm in diameter, with an envelope. Its genome consists of single-stranded negative-sense RNA encoding 10 proteins: fusion protein (F), attachment protein (G), small hydrophobic protein (SH), two matrix proteins (M1 and M2), three nucleocapsid proteins (N, P, and L), and two non-structural proteins (NS1 and NS2). The viral envelope has glycoprotein spikes but lacks HA, NA, and HL.

The virus cannot grow in chicken embryos but replicates slowly in various cell cultures, showing cytopathic effects after 2-3 weeks. Characteristic changes include syncytial formation with multinucleated giant cells containing eosinophilic cytoplasmic inclusions.

III. Etiology

RSV is the most common viral cause of pneumonia in children, causing interstitial pneumonia and bronchiolitis. Studies show it accounts for 48% of viral pneumonia and 58% of bronchiolitis cases in Beijing (1980-1984), 31.4% in Guangzhou (1973-1986), and 20-25% of infant pneumonia and 50-75% of bronchiolitis cases in the United States.

IV. Epidemiology

• - Highly infectious
• - Peak Season: Winter and early spring
• - Transmission: Respiratory droplets, contaminated surfaces
• - Incubation Period: 4-5 days, with viral shedding lasting 1-5 weeks

V. Clinical Manifestations

RSV primarily affects children under 3 years, with severe cases most common in infants 1-6 months old. Initial symptoms include coughing and nasal congestion. About two-thirds of cases present with high fever (up to 41°C), typically lasting 1-4 days. Moderate to severe cases may show respiratory distress, cyanosis, and chest retractions.

VI. Diagnosis and Treatment

Diagnosis relies on viral isolation and serological testing. Rapid diagnostic methods include immunofluorescence testing of nasopharyngeal secretions and RT-PCR viral nucleic acid detection. Treatment is primarily supportive, with antibiotics used only for secondary bacterial infections.

VII. Recent Developments (2023)

Vaccines:

• - March 2023: GSK's RSV vaccine candidate RSVPreF3 OA received FDA advisory committee recommendation for adults 60 and older.
• - May 2023: FDA approved GSK's Arexvy vaccine for adults 60 and older.
• - September 2023: Japan approved Arexvy as its first RSV vaccine for older adults.

Outbreaks:

• - June 2023: Chile reported its worst RSV outbreak in years, with four infant fatalities.
• - November 2023: RSV ranked third among respiratory infections in Beijing's population-wide surveillance.

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Accurate diagnosis of respiratory pathogens depends on quality specimen collection. Mantacc's flocked swab for respiratory virus sampling offer reliable specimen collection technology, supporting precise detection and diagnosis of these pathogens.

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