Parasites

last authored: Feb 2010, David LaPierre
last reviewed:

 

Recommended External Sites

Centre for Disease Control - Division of Parasitic Diseases

 

 

Introduction

Parasites are eukaryotic organisms that are distinct from fungi and do not contain chlorophyll. They are a mixed group of protozoa, helminths, and ectoparasites.

Parasites adapt to their existence by developing attachment mechanisms (ie hooks), defence mechanisms (ie nematode resistance to digestion), or increased reproductive capacity (ie Ascaris). Some parasites require humans as a host to complete their lifecycle; others are free living in the environment.

The immune response to parasites occurs with varying degrees of success.

 

Protozoa are single-celled organisms that reproduce by binary fission. They require an aquatic environment and can often ingest solid particles. Protozoa may be amoebae, flagellates, sporozoa.

 

Protozoa Cryptosporidium parvum Cyclospora cayetanensis Entamoeba histolytica Giardia lamblia Plasmodium falciprum Toxoplasma gondii Trichomonas vaginalis Trympanosoma spp

Helminths Cestodes Taenia spp (tapeworms) Trematodes Schistosoma spp Nematodes Ascaris lumbercoides Enterobius vermicularis Filaria Hookworms

Ectoparasites Ticks Fleas

 

Parasites are primarily diagnosed by direct examination of stool samples following staining techniques.

 

Resources and References

http://dpd.cdc.gov/dpdx/default.htm