Infectious Dose, Immunity and Transmission of Respiratory Pathogens, with Special Reference to Sars-CoV-2

Authors: Venkatesan P*

DOI: 10.23880/eij-16000191

Volume 5, Issue 2

Abstract

Particles of respiratory fluid emitted by an infected host convey respiratory pathogens to the next host. These particles vary in size from aerosols (<5μm) to larger droplets. Pathogens such as Mycobacterium tuberculosis depend on aerosols to reach the required target of infection within alveoli. Many respiratory viral pathogens may be implanted along the length of the respiratory tract. The probability of infection depends on the balance of infectious dose versus local defenses at sites of cells bearing relevant viral receptors. In the presence of partial immunity, the infectious dose threshold is likely to be higher. Such doses may only be achieved with exposure to larger respiratory particles like droplets, which by virtue of size convey a higher pathogen load. While droplet respiratory protection may provide good protection in the presence of some immunity, in nonimmune populations greater protection against < 5 μm particles is required.

Keywords: Infectious Dose; Immunity; Respiratory Particles; Droplets; Droplet Nuclei; Aerosol; Aerosol Transmission; SARS-CoV-2; Respiratory Transmission

View PDF