What are the two major groups of parasites ofmedical importance?

Protozoa

* Protozoa are single-celled organisms that lack a cell wall.

* They are typically much smaller than multicellular animals and can only be seen with a microscope.

* Some protozoa are free-living, while others are parasitic.

* Parasitic protozoa can cause disease in humans by directly damaging cells or by producing toxins.

* Some of the most common parasitic protozoa include:

* Malaria parasites (Plasmodium spp.)

* Leishmania parasites (Leishmania spp.)

* Trypanosoma parasites (Trypanosoma spp.)

* Giardia intestinalis

* Cryptosporidium parvum

Helminths

* Helminths are multicellular parasites that include worms.

* They are typically larger than protozoa and can be seen with the naked eye.

* Helminths can cause disease in humans by mechanically damaging tissues, by blocking blood flow, or by transmitting other pathogens.

* Some of the most common helminths include:

* Roundworms (Ascaris spp.)

* Tapeworms (Taenia spp.)

* Flukes (Schistosoma spp.)

* Hookworms (Ancylostoma duodenale)