About 3,000 children each year in the United States are born with the disease, which can cause mental retardation, vision or hearing loss and even infant death. Ranchers are often on the lookout for a parasite called Haemonchus, which can be especially harmful to sheep and goats. It is a blood-sucking worm more than an inch in length and can be a killer, Craig says. Sheep and goats get it through grazing and poor pastures, and a female can lay more than 5,000 eggs in a single day infesting pastures with millions of her offspring. Horse lovers should be aware of Cyathostomes, a group of parasites that multiply to staggering numbers, Craig says.
Some horses can have thousands and live normal lives.
But if the parasite load increases too much, an effective de-worming program must be started and it can take a long time to be show results. Craig says researchers can study the parasites and their life cycles, thereby learning how to attack the creatures with effective medications. We are trying to understand the ways parasites survive. We know that chemical agents can only go so far. You can't bomb the world with pesticides trying to eliminate parasites because then you've caused an even bigger health problem.