Chicken Pox is also known as Varicella is an acute and highly contagious disease. People who have never had chickenpox can get infected just by being in a room with someone who has the disease. If one member in the family gets chickenpox, he usually will infect another family member unless precautions are taken.

A person who gets infected will take 14 to 21 days before the chickenpox rash starts appearing on him. Once infected the person can infect another person from up to 48 hours before the initial rash and remains infective until all the blisters have burst all the crusts have disappeared. The chickenpox from an infected person spreads by -

Airborne droplets that are spayed when they cough or sneeze

Direct contact with discharge from the blisters of the skin

Coming in contact with Herpes or Shingles infection

The most common cause of infection is through the respiratory droplets that are inhaled by another person.