The virulence of the microbes should be high to cause an active infection.
Explanation:
Virulence is the actual potential or ability of a pathogenic microbe to infect a host. Even with a high median infectious dose to cause an infection, it is the virulence which defines the level of pathogenicity or ability of the pathogens like the foodborne pathogens to cause and active infection.
An active infection is caused when virulence of the pathogen is high. The virulence factors are surface receptors, surface coats, and toxins.
Virulent bacteria cause active infection by adhesion, colonization, invasion, immune response inhibitors, or as toxins. A virulent virus replicates rapidly and modifies the host’s defensive mechanism