Coconut oil and pumpkin seeds are good parasite killers for pregnant women and small children. Let him eat as many of the pumpkin seeds as he wishes, but please make sure they are not salted and hopefully are raw. The coconut oil can be found in any health food store and is easily mixed with smoothies to disguise its presence, although it tastes good. A couple of teaspoons of the coconut oil to start, as it can be a laxative also.
A couple of drops of Oil of Oregano in fruit juices will be very helpful also, and will do no harm. It will increase bile for better digestion, and is also a parasite killer.