Title: 5.2: Parasitic Helminths - Biology LibreTexts
Headings: 5.2: Parasitic Helminths
5.2: Parasitic Helminths
Learning Objectives
Nematoda (Roundworms)
Exercise 5.2. 1
Platyhelminths (Flatworms)
food for worms?
eradicating the guinea worm
Key Concepts and Summary
Multiple Choice
Fill in the Blank
Short Answer
Critical Thinking
Footnotes
Contributors and Attributions

Content: 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)
Phylum Nematoda (the roundworms) is a diverse group containing more than 15,000 species, of which several are important human parasites (Figure 5.2. 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; females may reach lengths greater than 1 meter. A. lumbricoides is also very widespread, even in developed nations, although it is now a relatively uncommon problem in the United States. It may cause symptoms ranging from relatively mild (such as a cough and mild abdominal pain) to severe (such as intestinal blockage and impaired growth).