You may or may not see dead worms. Sometimes dead worms will be expelled, sometimes they are absorbed by the chickens digestive tract. With Wazine I believe you repeat in 30 days, then after that depends on if they are reinfected. I honestly don't know about ivermectin, I don't use it for worms. The only way to know for SURE that treatment was effective is to have a fecal done to see if any eggs are present. (There are mail in options if you don't have a vet that will do it.) Roundworms are really easy to pick up in the environment and reinfection is common, the eggs survive a very long time in the soil. You may have to put yours on a regular worming schedule to keep them controlled. Some people can do once or twice a year, some must do it more often, every flock is different and it depends on the parasite load in your environment.