Everyone and his brother will tell you that wild caught feeders carry diseases. Fact is, they have less chance of having a disease or parasite than store bought feeders. Store bought feeders are raised in very poor conditions and in very cramped quarters. The slightest hint of disease in one feeder spreads like wild fire to the others. Very little or no care or consern is given to them before they are shipped out.
Wild fish are not kept in close quarters so if a fish in that eco system is sick, there is less chance of contact and spreading the disease. Wild feeders are not perfect, but they are way better than what we are forced to buy.