What are the ways viral pneumonia is transmitted?

Updated: Mar 24, 2021
  • Author: Zab Mosenifar, MD, FACP, FCCP; Chief Editor: John J Oppenheimer, MD  more...
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Answer

The mechanism of viral transmission varies with the type of virus. Routes include large-droplet spread over short distances (< 1 m), hand contact with contaminated skin and fomites and subsequent inoculation onto the nasal mucosa or conjunctiva (eg, rhinovirus, RSV), and small-particle aerosol spread (eg, influenza, adenovirus). Some viruses are extremely fastidious, whereas others have the capability of surviving on environmental surfaces for as long as 7 hours, on gloves for 2 hours, and on hands for 30 minutes.

Transmission routes for selected viral pneumonias are as follows:

  • Environmental factors (adenovirus, enterovirus, rhinovirus)

  • Direct contact with contaminated objects (VZV)

  • Transplantation of contaminated organs (cytomegalovirus [CMV]) or blood products (CMV)

  • Lower-respiratory aspiration of virus asymptomatically shed in the saliva (CMV, herpes simplex virus [HSV])

  • Reactivation of a latent infection (HSV, CMV)

  • Hematogenous spread (CMV)

  • Spread by healthcare personnel (SARS, measles, adenovirus, parainfluenza virus, RSV).

Hantavirus transmission is thought to occur primarily through inhalation of infected excreta from diseased rodents. The virus is also present in rodent saliva, so transmission can also occur from bites.

A number of viruses, including adenoviruses, influenza virus, measles virus, PIV, RSV, rhinoviruses, and VZV, are easily transmitted during hospital stays and cause nosocomial pneumonia. Adenoviruses, influenza viruses, PIV, and RSV account for 70% of nosocomial pneumonias due to viruses.


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