I have a bantam cochin and a frizzle. The cochin came to me almost a year ago, only a couple mo. old with two other birds. They all had very bad roundworm infestation which I did not figure out until too late. I noticed the large worms in their stool and treated them with pyrantel, which did not do the trick. A couple mo. later they had very tiny almost unnoticable worms is their stools- 2 of the 3 became ill at the same time even with a vet visit and antibiotics/wormer 2 of the 3 had passed away. I treated the remaining bird with piperazine, and later panacur hoping that she is now worm free. However she is still thin. I would like to treat her again just to be safe. I have taken in a cochin frizzle and would like to treat her also in case she has been exposed thru the other hen's droppings. I would like to know what i can go buy at the tractor supply that will not be a waste as I have just two light weight brids to treat.... Also, I am sure the ground is now contaminated. So what can i do to the ground, and how often should I treat the birds?