Pathogenic determinant a characteristic of a pathogen and that explains at least in part it mechanism of pathogenicity or harm. Pathogenesis the steps involved in expression of a pathogens harmful affects. Many groups of organisms are parasitic and all animals are parasitized.
Some parasites are totally dependent while others are only partially.
2.3 Parasite development can be controlled by the host. Many bacteria require a host receptor in order to establish infection. The host receptor is genetically controlled as is the pathogenic determinant on the parasite. Such signals or lack thereof may determine specificity and account for ability to infect only one host versus another. 2.5 Parasites have been responsible for the development of host inflammatory and immune responses in an attempt to avoid the pathogenesis of the disease process.