1. Causative agent
Causes of chickenpox
As mentioned above, chickenpox is caused by a virus, called varicella zoster. People become infected after being in contact with an infected child or adult.
Chickenpox is one of the most infectious diseases around - approximately 90% of those who have never had chickenpox or were not vaccinated will become infected when they come into contact with the varicella zoster virus.
Chickenpox and colds and flu spread in a similar way. Droplets of water that are expelled from the nose and mouth of the infected person through coughs and sneezes are inhaled by those around them. The contaminated droplets float in the air.
If the contaminated droplets land on surfaces and objects, they too can become sources of infection if other people touch them.