Roundworm—Dioctophyma renale causes Dioctophymiasis. Symptoms of this disease in the human include renal dysfunction, blood in the urine and kidney spasms. Urinalysis will reveal the eggs of D. renale but if the parasite is male, it can burrow into the abdomen and must be removed surgically. Eating raw or undercooked fish, frogs or crawfish livers can cause the disease. Here is a picture of a D. renale adult inside a carcass and an egg in the urine:

Roundworm-Dioctophyma renale (Kidney-Urine) 1

Dictophyme renale adult

Roundworm-Dioctophyma renale (Kidney-Urine) 2

Dioctophyma renale egg. Note pitted look.