The viruses causing common warts spread through direct contact from a child to another.
Even indirectly through contact with personal items or in public places such as public baths, pools etc.
As soon as the virus contaminates the skin it requires some time (incubation time) even months before the lesions become clinically visible.
The virus can remain inactive and latent in the skin for some time so it is impossible to determine when exactly your child came in contact with the virus.
Children are generally more susceptible to developing warts as they don’t have anti bodies against it and come ofthen on contact with people who have warts.