patogenicitas

Patogenicitas, or pathogenicity, is the capacity of a microorganism to cause disease in a host. It reflects whether an organism can establish itself, invade tissues, and provoke pathological changes. Pathogenicity is distinct from virulence, which describes the degree of harm a pathogen causes, and from transmissibility, which concerns how easily a pathogen spreads between hosts.

Determinants of pathogenicity include features of the pathogen, such as adhesins, capsules, toxins, secretion systems, and metabolic capabilities; host factors such as immune status, genetic susceptibility, microbiome composition, and tissue barriers; and environmental conditions like co-infections and stress.

Mechanisms include adherence and colonization, invasion of tissues, production of toxins or immune-modulating effects, evasion of host defenses, and nutrient capture. Some organisms are primary pathogens capable of causing disease in healthy hosts; others are opportunistic, causing disease mainly in weakened or compromised individuals.

Assessment of pathogenicity uses concepts like infectious dose (ID50) and lethal dose (LD50) in experimental models; Koch's postulates are historical. In modern practice, pathogenicity is inferred from infection models, clinical data, and molecular determinants; risk is context-dependent and influenced by host and pathogen traits.

Evolutionary processes such as horizontal gene transfer give rise to new virulence factors and pathogenicity islands. Understanding patogenicitas informs public health, including diagnostics, vaccines, and infection control.