The vast majority of viral infections are non-pathogenic. The infectious process in the animal kingdom. Mechanism of Entry. First question to ask, how do viruses get into the individual. Viruses generally can not pass through the skin, the surface of which is covered with hair, feathers or in the case of man with a thick impermeable layer of dead keratinized cells unless deliberately bypass the skin by injection.
Epidermis is devoid of lymphatic vesicles.
Discuss Fig 6-1 for portals of entrance. In the case of man can get through the skin by penetration of wound sometimes too small to be noticed, or through injection by insect bite or other kind of bite, such as in the case of rabies resulting from a bite. Hep C gets into the blood stream through tattooing. . However the most frequent mode of transmission of viruses, particularly in an urban, affluent environment is not by insect bites, but is by air and food. There are some viruses that do infect the skin, but often they arrive at the skin through internal means.