Are parasites contagious from human to human?

Depends: There are many kinds of parasites. Most are not transmitted from person to person, but some are. Giardiasis and amebiasis can be transmitted from person to person, usually during sex when there is oral-fecal or oral-anal contact. Pinworms are easily transmitted within households, especially among children. Skin parasites such as scabies and crab lice are also transmitted from person to person.