They look like roundworms. They are very common. You probably had them for ages. Usually by the time you notice them it has been decades. Tests are totally unreliable incl the elisa as in chronic infections the antibodies are close to 0 in the blood. I think seeing them is a good enough confirmation! I would not be surprised if you had other infections as well. Dr Yu in st louis is the only doctor i know of who treats parasites with success (more or less) if you can afford it.