Rhinoviruses

The rhinoirus group derives its name from predominant site of replication (the nose). The rhinovirus group is the commonest cause of the acute resp illness known as common cold.Over 100 serotypes of rhinoviruses are currently recognized.

Pathogenesis and clinical significance

Transmission is through drolet and hand to hand contact followed by self inoculation of virus into the nose and conjunctiva.

Incubation period is 2-3 days.

The virus multiplies locqally without blood invasion.

Peak of virus shedding coincides with acute rhinitiss, and virus becomes usually undetectable after 4 or 5 days.

Type specific immunity that correlates best with the local production of IgA.

2ry bacterial infection may cause otitis media, sinusitis, bronchitis or bronchopneumonia especially in children.

Repeated infection of common cold could be explained by :

1. Multiplicity of antigenic types ( over 100)
2. Being a superficial infection, serum antibodies plays no signigficance role in immunity
3. Immunity is mainly superficial by IgA and interferon (short term immunity)

Vaccine produce is not practical.