of the structure of a roundworm on a white background

microscope education concept contaminated duodenum albendazole mebendazole nematoda parasitology toxocariasis pyrantel pamoate ascaris lumbricoides infectious levamisole healthy system malnutrition abdominal pain sanitation endoparasite swelling roundworm animal parasite worm parasitic nematode helminth science zoology invertebrate nature wildlife background dog ugly isolated human intestinal intestine tapeworm medical health disease ascariasis female biology vector illustration structure white