toxocara canis second stage larvae hatch from eggs

parasite worm parasitic microscope parasitology human disease ascarid helminth microscopy intestine nematode roundworm ascaris infection roundworms diagnosis photomicrograph eggs training animal ascariasis life biology nematoda detail education toxocaridae increase transmission nematodes veterinary uterus toxocara dogs hospital hosts cultivation doctor toxocariasis worms hatch lumbricoides spirurida medicine healthcare canid treatment mitosis macro