Round worms in human intestine, computer illustration. Roundworms, or nematodes, include numerous free-living and pathogenic species. Nematodes that c

Round worms in human intestine, computer illustration. Roundworms, or nematodes, include numerous free-living and pathogenic species. Nematodes that commonly parasitise in humans include ascarids (Ascaris sp.), pinworms (Enterobius sp.), (Ancylostoma sp. and Necator sp.), whipworms (Trichuris trichiura), and extra-intestinal parasites filaria.