Worms can easily pass from pets to people, through:
In the UK tapeworm, and a type of roundworm known as toxocara, are the most common types of worm transferred from dogs and cats to their unsuspecting owners.
Those most at risk are children, the elderly and those with reduced immune systems but everyone should get into the habit of washing their hands regularly, especially before eating. Ensuring the family pet gets wormed at regular intervals with a vet strength wormer will get rid of the most common worm infestations.
80% of children kiss their pet1. That conjures up a lovely image, until you are hit with the realisation that those pets may have just ingested worm eggs...
1. McNicholas J. Effect of pet ownership on immune functioning in children & Nature of the relationship between children and pets. University of Warwick March 2002