fruit fly parasites?

Ok so this isn't exactly an insect, but my flightless fruitflies have been infected with what I think are nematodes? but I have no idea how they got there or if they are dangerous or not. Has anyone ever heard of or had problems with nematodes as parasites in their fruit fly cultures? The nematodes are very small, clear and move like a snake along the plastic sides of the jar the flies are in. Also I found these strange looking oval shaped things with spikes? which I think are egg cases maybe or something? not sure. Anyone have any ideas? I used a microscope to get the pictures.
I live in Maryland if that helps at all in identification.