What is the term for the ability of a pathogen to establish an infection within a host?

The term that describes the ability of a pathogen to establish an infection within a host is known as infectivity. This concept refers specifically to how effectively a pathogen can enter a host, reproduce, and cause disease. Infectivity is a key factor in understanding how diseases spread and the potential for public health implications, as it determines the likelihood of transmission.

Pathogenicity, on the other hand, refers to the ability of a pathogen to cause disease in a host once it has established itself, which encompasses both the infectivity and the severity of the disease caused. Virulence relates to the degree of pathogenicity; it measures the severity or harmfulness of the infection. Antigenicity pertains to the ability of a pathogen to provoke an immune response. Understanding these distinctions highlights why infectivity is the correct terminology for the ability of a pathogen to initiate an infection.