Define protozoa

Recent Examples on the Web This disease is caused by a tiny protozoan the mosquito picks up, and in some areas, mosquitoes are such effective vectors of malaria that 100 percent of them carry the disease. — John Sass, Field & Stream, 11 Apr. 2023 In many parts of the world, even the water in your glass could be contaminated with protozoan parasites. — Bob Holmes, Discover Magazine, 21 Nov. 2018 The protozoan Toxoplasma is just another stowaway within the system and one that warrants more study. — Gustavo Arrizabalaga And Bill Sullivan, Scientific American, 1 Mar. 2015 Soon after, he was diagnosed with sarcocystis, a disease caused by a protozoan parasite carried by opossums. — Lyndsay Winkley, San Diego Union-Tribune, 22 Apr. 2023 The parasitic protozoan known as Cryptosporidium has an egglike life stage that can endure more than six months at 41 degrees Fahrenheit — just above refrigerator temperature — and ascaris roundworm eggs can stay viable in sewage sludge for several years, hatching once they are ingested by a host. — Nala Rogers, Discover Magazine, 1 July 2019 The problem was in the current underneath, in the form of protozoan cysts spread by animal (including human) droppings that, when swallowed, result in a serious intestinal disorder: giardiasis—otherwise known as hiker’s diarrhea, backpacker’s curse, or beaver fever. — Keith Mccafferty, Field & Stream, 19 June 2020 But three genes stood out: PPP3CA and DYNC1I1, which are associated with an immune response aga...

\( \newcommand\) • • • • Learning Objectives After completing this section you should be able to perform the following objectives. • Briefly describe protozoa. • Briefly describe 3 ways protozoans may reproduce asexually. • Define the following: • trophozoite • protozoan cyst. Protozoa are unicellular eukaryotic microorganisms lacking a cell wall and belonging to the Kingdom Protista. Although there are nearly 20,000 species of protozoa, relatively few cause disease; most inhabit soil and water. Protozoa reproduce asexually by the following means: • fission: One cell splits into two. • schizogony: A form of asexual reproduction characteristic of certain protozoa, including sporozoa, in which daughter cells are produced by multiple fission of the nucleus of the parasite followed by segmentation of the cytoplasm to form separate masses around each smaller nucleus. • budding: Buds form around a nucleus and pinch off of the parent cell. Some protozoa also reproduce sexually by fusion of gametes (Figure \(\PageIndex\) : Life Cycle of Plasmodium, the Protozoan that causes Malaria. (1) A female Anopheles mosquito carrying malaria-causing parasites feeds on a human and injects the parasites in the form of sporozoites into the bloodstream. The sporozoites travel to the liver and invade liver cells. (2) Over 5-16 days*, the sporozoites grow, divide, and produce tens of thousands of haploid forms, called merozoites, per liver cell. Some malaria parasite species also produce hypnozoi...

Recent Examples on the Web Where swamps were drained and highways laid, the potential of malaria was unlocked in its worst form – Plasmodium falciparum – a deadly mosquito-borne protozoon. — Kyle Harper, Discover Magazine, 15 Dec. 2017 These examples are programmatically compiled from various online sources to illustrate current usage of the word 'protozoon.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors.