Virus diseases

A viral disease (or viral infection or infectious disease), occurs when an organism's body is invaded by pathogenic viruses, and infectious virus particles (virions) attach to and enter susceptible cells.Vertical and sexualVaricella:Varicella: A viral disease (or viral infection or infectious disease), occurs when an organism's body is invaded by pathogenic viruses, and infectious virus particles (virions) attach to and enter susceptible cells.