noun, plural: pathogenicities
The capability (of a pathogenic agent) to cause disease
Pathogenicity pertains to the ability of a pathogenic agent to cause disease. Examples of pathogenic agents are infectious bacteria, viruses, prions, fungi, viroids, and parasites causing disease. Their capability to produce disease is associated with their characteristics they acquired during their effort to survive in their host. The host may be a particular animal, plant, fungal, or another microbial species.
A related term to pathogenicity is virulence, which refers to the degree of pathogenicity of a particular organism. For instance, certain disease-causing microbes are capable of producing and releasing toxins, invading tissues, competing for nutrients and the ability to suppress the immune mechanism of their host. Microbial species that are pathogenic are those that cause diseases such as smallpox, mumps, measles, rubella, ebola, etc. For instance, the human immunodeficiency virus (HIV) that causes HIV infection and acquired immunodeficiency syndrome (AIDS) is capable of infecting cells in the human immune system, e.g. CD4+ T cells, macrophages, and dendritic cells. They are not only able to evade the immune response and mechanism of such cells. They are also capable of gaining entry into, proliferate, and kill these cells.