"Does Iodine deficiency cause parasites to take hold? thanks."
It will make it easier.
If the thyroid has enough Iodine it uses it to kill pathogens in the blood. If you drink water with Lugols in it many pathogens will be killed when they come into contact with it. If a woman takes 50 mg per day of LugolsIodine it is very unlikely that she will ever develop breast cancer. Etc etc etc.
Safe for children. If a pregnant mother gets a certain amount of Iodine the child will have an increased IQ.