Patogénia

Patogénia, also known as pathogenicity, is the ability of a biological agent to cause disease in a host. It arises from complex interactions between the pathogen’s traits and the host’s defenses and can be influenced by environmental conditions. Pathogenicity is distinct from virulence, which refers to the degree of harm or severity of disease once infection is established; a pathogen may be pathogenic but have low virulence, or highly virulent but rarely encountered.

Pathogens employ a range of virulence factors to initiate disease. These include adhesins for attachment to host cells, invasion factors and secretion systems to enter tissues, capsules and other surface structures to resist phagocytosis, enzymes and toxins that damage tissues, and mechanisms to modulate or evade the immune response. Some pathogens cause disease primarily through toxins, while others rely on tissue invasion and inflammatory responses.

Host susceptibility and microbial fitness influence pathogenicity. Age, genetics, immune status, microbiota composition, and prior exposure shape outcomes. Dose and route of entry, co-infections, and environmental stress can alter the course of disease.

Assessment of pathogenicity in research uses concepts such as infectious dose (ID50) and lethal dose (LD50) and may distinguish primary pathogens from opportunistic pathogens. Pathogenicity can also be linked to genetic elements such as pathogenicity islands and other virulence determinants that encode factors enabling disease.

In sum, patogénia describes the capacity of an organism to cause disease, resulting from the balance between pathogen traits and host defenses, and it is a central concept in microbiology and infectious disease.