<prompt> Infectivity period of chickenpox is: March 20091 day before and 4 days after appearance of rash4 days before and 1 day after appearance of rashOnly when scab fallsEntire incubation period  <response>: Ans. A: 1 day before and 4 days after appearance of rash Chickenpox varicella is a highly infectious disease that spreads from person to person by direct contact or by air from an infected persons coughing or sneezing. Touching the fluid blister can also spread the disease. A person with chickenpox is infectious from 1-2 days before the rash appears. The contagious period continues until all blisters have formed scabs, which is about 4 to 5 days after the rash. After the spots have scabbed over, the sufferer is still highly contagious, from 10 to 21 days, meaning they can still spread the virus through close contact, breathing, and even sleeping in someones bed. It takes from 10 to 21 days after contact with an infected person for someone to develop chickenpox. 