Micro organisms are divided into three classes:

-Bacteria

-Viruses

-Fungi

Chicken pox is a viral infection caused by vaicella zoster virus or (VZV). The most important point to get is that not all micro organisms are infectious. The infectious micro organisms are known as Pathogens. Humans have developed a defence mechanism to defend them from Pathogens called the Immune System. The Immune System consists of white blood cells, and they have another name: Leukocytes. White blood cells include macrophages which are a type of phagocytes. Phagocytes are large cells that attack and feed on foreign microscopic things out of a cell, and then digest them, this also known as engulfing and digesting. However, that is not the only type of a white blood cell, there is an other type which is the lymphocyte. Lymphocytes also have two sub-types which are the B cells and the T cells. B cells get their name from their development of bone morrow. B cells create antibodies. T cells get their name from their development of a small organism known as thymus gland. T cells are responsible for attacking cells infected by the help of macrophages and they activate phagocytes. B cells cause antibodies that are proteins to counteract an antigen. Antigens are structures that are in all pathogens. Antibodies try to bind with antigens disabling them by activating a cascade of nine proteins , known as complement. Complement help assist the antibodies in destroying the bacteria.The Pathogens are the labelled based on their antigens, the B cells then produce memory cells that help create antigens for that pathogen i.e. chicken pox which helps the antibodies to react quickly in case of reinfection. Once the immune system reaches this level, it has gained a status known as “Acquired Immunity” against that pathogen.