Back
ditki Logo
medical & biological sciences
All Access Pass - 3 FREE Months!
Institutional email required, no credit card necessary.
Parasite Biology - Helminths

Parasite Biology - Helminths

Start 1-Month Free Access!
No institutional email? Start your 1 week free trial, now!
Animalia parasites
Helminths - Worms
  • Multicellular, and most adults are anaerobic.
  • Reproduction may be hermaphroditic or involve separate male and female sexes.
Nemathelminthes* comprise the Nematodes, aka, the roundworms. Platyhelminthes comprise the flat Cestodes and Trematodes.
  • Helminths use their muscular body walls for motility.
  • They can grow to be quite large within their human hosts, which can lead to mechanical damage and obstruction.
  • Roundworms = Nematodes
To remember this, know that "nemo" means "thread". Example: Trichinella spiralis
  • Round and coiled
  • Outer covering is cuticle
  • Has a definitive mouth and anus.
  • Flatworms
Cestodes aka, tapeworms Ex: Echinococcus
  • Cestodes comprise segments covered in a tough tegument.
  • This species has two suckers on one end.
  • Cestodes are hermaphroditic.
Trematodes aka, flukes Ex: Paragonimus, the lung flukes
  • Leaf-shaped
  • Sucker at one end
  • Tegument
  • Hermaphroditic
Ex: Shistosoma
  • Separate male and female sexes that live as a unit; it's helpful to know that "shitosoma" means "split body".
  • Male, which has snow-pea like shape.
Female is smaller, slenderer, and resides within the male's gynecophoral canal.
References
Castro, Gilbert A. "Helminths: Structure, Classification, Growth, and Development." In Medical Microbiology, edited by Samuel Baron, 4th ed. Galveston (TX): University of Texas Medical Branch at Galveston, 1996. http://www.ncbi.nlm.nih.gov/books/NBK8282/.
"CDC - DPDx - Schistosomiasis Infection," December 18, 2017. https://www.cdc.gov/dpdx/schistosomiasis/index.html.
"CDC - DPDx - Trichinellosis," December 19, 2017. https://www.cdc.gov/dpdx/trichinellosis/index.html.
"Echinococcus Granulosus." Accessed November 1, 2018. http://bioweb.uwlax.edu/bio203/s2009/breunig_mich/Reproduction.htm.
Murray, P. R., Rosenthal K.S., & Pfaller, M.A. Medical Microbiology. 8th ed. Elsevier, 2016.
"PARA-SITE." Accessed October 29, 2018. http://parasite.org.au/para-site/contents/protozoa-intoduction.html.
Image Credits:
"CDC - DPDx - Schistosomiasis Infection," December 18, 2017. https://www.cdc.gov/dpdx/schistosomiasis/index.html.
"CDC - DPDx - Trichinellosis," December 19, 2017. https://www.cdc.gov/dpdx/trichinellosis/index.html.
———. "CDC - Echinococcosis," May 2, 2017. https://www.cdc.gov/parasites/echinococcosis/index.html.
"Trichinella Spiralis." Wikipedia, July 9, 2018. https://en.wikipedia.org/w/index.php?title=Trichinella_spiralis&oldid=849471397.

Related Tutorials