Varicella-zoster virus (VZV) causes the chickenpox infection. Most cases occur through contact with an infected person. The virus is contagious to those around you for one to two days before your blisters appear. VZV remains contagious until all blisters have crusted over. The virus can spread through:
- saliva
- coughing
- sneezing
- contact with fluid from the blisters
Risk factors
Exposure to the virus through previous active infection or vaccination reduces risk. Immunity from the virus can be passed on from a mother to her newborn. Immunity lasts about three months from birth.
Anyone who has not been exposed may contract the virus. Risk increases under any of these conditions:
- You have had recent contact with an infected person.
- You are under 12 years of age.
- You are an adult living with children.
- You have spent time in a school or child care facility.
- Your immune system is compromised due to illness or medications.
Once someone is infected, the virus usually incubates for 14 to 16 days before a rash appears, although incubation can last from 10 days to 21 days. There are no symptoms during incubation and a person doesn’t become contagious until 1 to 2 days before the rash appears. The person remains contagious until all the blisters have dried and scabs have formed.
It’s worth noting that once a person has had chickenpox, the virus remains dormant in their body, and can reactivate later in life, causing shingles (Herpes Zoster).
It is important to seek prompt medical care in cases of chicken pox to avoid spreading.