What term describes the ability of a pathogen to cause disease?

The term that describes the ability of a pathogen to cause disease is indeed pathogenicity. Pathogenicity refers to the capacity of an organism to produce an infection and leads to disease in a host. This concept encompasses the mechanisms by which a microbe interacts with a host's biological systems in a way that can disrupt normal functions and result in disease.

Pathogenicity is distinct from other related terms such as virulence, which fits within the broader category of pathogenicity. Virulence specifically measures the degree of pathogenicity - the severity or harmfulness of the disease that the pathogen can cause, often affected by factors like toxin production or the pathogen's ability to evade the immune response.

Infectiousness, on the other hand, describes how easily a pathogen can be transmitted from one host to another. Although a pathogen may be highly infectious, this does not necessarily correlate with its ability to cause disease.

Colonization refers to the establishment of a microbe within a host without necessarily causing disease; it's possible for a pathogen to colonize without showing pathogenic effects.

Overall, while all these terms are interconnected, pathogenicity is the most accurate and specific term for indicating a pathogen's capability to cause disease.