My opinion is, the infectious dose mean the minimum amount of pathogen (measured in number of microorganisms) required to cause an infection in the host
so it is already the lowest number of microorganism below it no infection will occur.
Thank you very much Dr. Hussein for your explanation. Then, can not we select a particular pathogen as low infectious dose category and not in that category. I realized from your explanation, it’s just a comparison between infectious dose of each pathogen to decide....
The exact infectious dose depends on the virulence of the strain, portal of entry, and susceptibility of the host. "Low" infectious dose is below 10^3: enteroinvasive, enteropathogenic, and enterohaemorrhagic Escherichia coli; Francisella tularensis; Listeria monocytogenes; Mycobacterium tuberculosis; Salmonella enterica; Streptococcus pyogenes.
Article Opinion Pathogenesis, Virulence, and Infective Dose