Parasitic Infections

Organisms that live on or in a host and obtain food from it at the expense of the host are called parasites.

Three main classes of parasites and diseases that plague humans, and most of the major parasites that can infect humans:

Class Protozoa – single-celled organisms that can live either freely or within a host.

  • Entamoeba histolytica (amoeba)
  • Giardia intestinalis (Giardiasis)
  • Leishmania (Leishmaniasis)
  • Balantidium coli (Balantidiasis)
  • Plasmodium falciparum (malaria)
  • Cryptosporidium (Cryptosporidiosis)
  • Toxoplasma Gondii (Toxoplasmosis)
  • Trypanosoma brucei (sleeping sickness)

Class Helminth – large, multi-cellular organisms (worms) what can live freely or within a host.

  • Group Flatworm
    • Trematodes (flukes) – Fasciola (liver flukes) and Schistosoma (blood flukes)
    • Cestodes (tapeworms) – Taenia spp., Echinococcus, and Diphyllobothrium
  • Group Thorny-headed worm (acanthocephalins)
    • Macracanthorhynchus hirudinaceous
    • Moniliformis moniliformis
    • Bolbosoma spp.
  • Group Roundworm (nematodes)
    • Whip worms – Trichuris trichiura
    • Hookworms – Necator, Ascaris, and Ancylostoma
    • Threadworms – Strongloides
    • Guinea worms – Dracunculus
    • Filarial worms – Wuchereria and Onchocerca

Class Ectoparasite – dependent on blood as a food source from their human hosts.

  • Ticks
  • Fleas
  • Lice
  • Mites




spp = species; plural



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