How are parasites and viruses similar?
Both are contagious diseases.
Both infect host organisms.
Both reproduce using host cells.
Both break down food using oxygen.

Both infect host organisms

Explanation: A virus is a microscopic particle that can infect the cells of a biological organism. ... They are similar to obligate intracellular parasites as they lack the means for self-reproduction outside a host cell, but unlike parasites, viruses are generally not considered to be true living organisms.

sex cells are usually half's then they find another half and make a fertilize egg