Microbiology and Immunology 2500A/B Lecture Notes - Lecture 2: Ascaris Lumbricoides, Ascariasis, Animal
Document Summary
Can be separated into 3 distinct phyla, each of which tends to be distinguished by body shape. In general, all metazoa are multicellular, but can vary in size from millimeters to, in some cases, meters in length. We will examine each of the 3 phyla and focus on individual species of particular importance: roundworms, flatworms, thorny-headed worms. The main species of ascaris that infects humans is ascaris lumbricoides. The global burden of ascaris infection is estimated to be between 0. 8-1. 2 billion people. These are large, round nematodes, with an adult size of 15-20cm in length. Ascariasis is the most common human helminth infection in the world. Although there is a worldwide distribution of the parasite in any warm and moist climate, most infections occur in tropical and subtropical areas, or where hygiene is poor. Ascaris is transmitted from ingestion of eggs in the soil, or via the fecal-oral route.