Chickenpox is a viral infection that causes the rash to form on the body and itching in it. Varicella-zoster virus is responsible for chicken pox or cheek. In most cases, it spreads from infected person to other people.
Pellagra is a disease that affects digestive tract, skin and nerves. Another major cause of pellagra is digestion problems in the body, due to which the niacin is not absorbed in the body. Niacin is also known as nicotine acid.