0.4 Taxonomy of clinically relevant microorganisms  (Page 3/3)

Protozoan pathogens

The relationships among the organisms (and thus their taxonomy) previously grouped under the name Protists are better understood than they were two or three decades ago, but this is still a work in progress. In 2005, the Eukarya were divided into six supergroups. S.M. Adl et al. “The New Higher Level Classification of Eukaryotes with Emphasis on the Taxonomy of Protists.” Journal of Eukaryotic Microbiology 52 no. 5 (2005):399–451. The latest high-level classification combined two of the previous supergroups to produce a system comprising five supergroups. S.M. Adl et al. “The Revised Classification of Eukaryotes.” Journal of Eukaryotic Microbiology 59 no. 5 (2012):429–514. This classification was developed for the Society of Protozoologists, but it is not the only suggested approach. One of the five supergroups includes the animals, fungi, and some smaller protist groups. Another contains green plants and three algal groups. The other three supergroups (listed in the three tables below) contain the other protists, many of them which cause disease. In addition, there is a large number of protist groups whose relationships are not understood. In the three supergroups represented here we have indicated the phyla to which the listed pathogens belong.

Parasitic helminths

The taxonomy of parasitic worms, all of which belong to the kingdom Animalia still contains many uncertainties. The pathogenic species are found in two phyla: the Nematoda, or roundworms, and the Platyhelminthes, or flat worms. The Nematoda is tentatively divided into two classes National Center for Biotechnology Information. “Taxonomy Browser: Nematoda.” http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=6231 , one of which, Chromadorea, probably contains unrelated groups. The parasitic flatworms are contained within three classes of flatworm, of which two are important to humans, the trematodes and the cestodes.