what causes chickenpox
Causes of chickenpox. Chickenpox is caused by the varicella zoster virus, which is very contagious. If you haven't had chickenpox before and someone you come into prolonged contact with has it, you're likely to catch it too.auses of chickenpox. Chickenpox is caused by the varicella zoster virus, which is very contagious. If you haven't had chickenpox before and someone you come into prolonged contact with has it, you're likely to catch it too.