Creeping eruption doesn't harm humans, all it does is form a snakelike tunnel underneath the top layer of your skin and you can see it on top of your skin. The larva dies off in 2-8 weeks which is average, but survival of 55 weeks has been reported. Treatment just makes the larva die off more quickly. But, no it can't harm humans if not treated.
If you continuously itch the area where the tunnel like things appear, it can cause bacteria on top of the skin which can lead to a skin dizease.