Title: Parasitic Helminths | Microbiology
Headings: Parasitic Helminths
Parasitic Helminths
Learning Objectives
Nematoda (Roundworms)
Clinical Focus: Anthony, Part 2
Think about It
Platyhelminths (Flatworms)
Think about It
Food for Worms?
Eradicating the Guinea Worm
Key Concepts and Summary
Multiple Choice
Fill in the Blank
Think about It

Content: However, the parasitic species often have limited digestive tracts, nervous systems, and locomotor abilities. Parasitic forms may have complex reproductive cycles with several different life stages and more than one type of host. Some are monoecious, having both male and female reproductive organs in a single individual, while others are dioecious, each having either male or female reproductive organs. Nematoda (Roundworms)
Figure 1. A micrograph of the nematode Enterobius vermicularis, also known as the pinworm. ( credit: modification of work by Centers for Disease Control and Prevention)
Phylum Nematoda (the roundworms) is a diverse group containing more than 15,000 species, of which several are important human parasites (Figure 1). These unsegmented worms have a full digestive system even when parasitic. Some are common intestinal parasites, and their eggs can sometimes be identified in feces or around the anus of infected individuals. Ascaris lumbricoides is the largest nematode intestinal parasite found in humans;