Final answer:
Adherence is critical in pathogenicity as it enables pathogens to attach to host cells, establish infection, and evade the immune system. It allows the pathogen to begin invading tissues, and influences the severity of disease and the ability of the host to mount an appropriate immune response.
Step-by-step explanation:
Importance of Adherence in Pathogenicity
Adherence is a crucial aspect of pathogenicity as it is the capability of pathogenic microbes to attach to the cells of the body, which is a critical step in establishing infection. Various pathogens use different adhesion factors, like adhesins, to adhere to the host tissue cells effectively. These adhesins can be proteins or glycoproteins and are found on the surface of pathogens including bacteria, viruses, and fungi.
One of the examples of bacterial adhesin is the type 1 fimbrial adhesin found on enterotoxigenic E. coli (ETEC), which allows it to attach to intestinal epithelial cells. Adhesion is fundamental for the pathogen to establish the initial foothold at the portal of entry, which enables subsequent invasion and spread within the host. The strength and specificity of adhesion can influence the degree of virulence, tissue damage, and the overall severity of infection.
It's also noteworthy that adherence can facilitate immune evasion; for instance, capsules used by bacteria not only assist in adhesion but also aid in avoiding phagocytosis by immune cells. Therefore, adherence is integral to a pathogen's ability to survive, propagate, and produce disease within a host, impacting why some individuals experience more serious illness compared to others when exposed to the same pathogen.