I agree with IVAN3 if you are to use drugs that is a good one and there are many ways to prevent or do away with worms.
This is not for everyone but I am going to use the cheapest rout every time that works and this works for me.
Diatomaceous earth food grade as a preventive and as well as a killer of worms and almost any other insects.
I buy it in bulk and its cheap some Co-Ops carry it I have to order it by mail.
In emergency cases and there are say gape worms and the Chicken is struggling to breath before I started to use diatomaceous earth I used a old home remedy of boiled tobacco juice and force fed a teaspoon once a day for two days and the worms were gone nicotine is one of the best insect killers.
In a pinch I have used that on several different kind of animals and it has always worked.
Do some research on diatomaceous earth food grade decide for your self what you will try.
I will check into it as well. I did purchase Valbasen but the label is for sheep etc. How much do I give to the turkey (of course I will have to weigh her).