The virus

Respiratory syncytial virus is a single-stranded RNA virus belonging to the family Paramyxoviridae.

Epidemiology

Route of spread

Respiratory syncytial virus is spread readily by direct contact with respiratory secretions, fomites and large droplets through the nose and eyes (but not the mouth). Nosocomial infections are common.

Prevalence

Respiratory syncytial virus has a worldwide distribution. In the developed world it occurs in epidemics in mid winter (November to February in the UK). Infection is common in young children; 70% are infected and 30% have clinical illness in their first year of life. Two per cent of infants have severe lower respiratory tract symptoms. All children are infected by 3 years of age, some having had more than one infection. Immunity is short lasting – just a few weeks or months. In families of pre-school age children as the primary case, 50% of family members will be infected. There are higher attack rates in nurseries and playschools.

Incubation period

3–6 days.

Infectious period

• Children are infectious for 9 days on average, but this can be much longer.

• Adults are infectious for about 2 days.

• Immunocompromised patients can be infectious for several weeks.

At-risk groups

Immunocompromised patients (e.g. those with severe combined immunodeficiency syndrome, bone-marrow transplant recipients, those on chemotherapy, HIV infected patients).