Aetiology and pathogenesis
Common cold diseases are due to multiple viruses, affecting the upper respiratory tract 3
Human Rhinovirus (HRVs ) 30-80% (a genus ofPicornaviridae with 99 known serotypes); Coronavirus10-15%; Orthomyxovirus 05-15%; Coxsackievirus; Echovirus; Paramixovirus (Human Parainfluenza Virus); Human respiratory syncytial virus (SRV); Adenovirus; Enterovirus; Metapneumovirus. In addition, over 200 viruses associated with common cold diseases are known and often more than one viral species is involved in the infection.
These viruses penetrate the mucosal layer of the nasal or bronchial mucociliary epithelium; this involves damage to the hair cells and a consequent release of bradykinin, prostaglandin, histamine and cytokines. These mediators promote the inflammatory response thus causing inflammation of the nasal tissues, detachment of hair cells and alterations of epithelial integrity. As a consequence, the subject sneezes and has a runny and stuffy nose. The mediators themselves are also responsible for laryngo-pharyngitis (sore throats)4