Respiratory Syncytial Virus and Human Metapneumovirus (Pnuemoviridae)

The Pneumoviridae family of viruses contains the respiratory syncytial virus (RSV) from the Orthopneumovirus genus and the human metapneumovirus (HMPV) from the Metapneumovirus genus. Both of these are enveloped, negative-sense RNA viruses characterized by a helical nucleocapsid. The G protein of these viruses facilitates the virus's attachment to respiratory epithelial cells, initiating infection, while the F protein triggers the fusion of infected host cells with adjacent uninfected cells, leading to the formation of multinucleated structures known as syncytia.

Transmission of these viruses primarily occurs through direct contact or large respiratory droplets. While typically resulting in mild respiratory diseases in healthy individuals, they can cause severe infections in vulnerable populations such as infants and the elderly. Premature children and those with asthma are at a higher risk of severe HMPV infection. Among adults, it's a less frequent cause of community-acquired pneumonia but can exacerbate chronic obstructive pulmonary disease (COPD). RSV is the leading cause of pneumonia and bronchiolitis in infants. High-risk groups for RSV include premature children and those aged 2 and below with underlying lung conditions. To mitigate its spread, especially in medical settings, it's crucial to isolate RSV-infected patients and adopt droplet precautions. For treatment and prevention, ribavirin can be used for immunocompromised patients (though it's contraindicated in pregnancy), and palivizumab, a monoclonal IgG antibody, offers preventive measures for high-risk children.