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Foodborne Illness
Published in Gary S. Moore, Kathleen A. Bell, Living with the Earth, 2018
Gary S. Moore, Kathleen A. Bell
Giardia lamblia is a protozoan flagellate found in areas with poor sanitation and in unfiltered surface water supplies (Figure 8.6). Giardia is considered to be the primary agent for diarrheal outbreaks associated with contaminated water supplies, having a prevalence of 3–7 percent in developed countries and 20–30 percent in LDCs.27 In the U.S., giardiasis is most common among those who travel to endemic areas and in child day care settings where constant diaper changing facilitates the spread from one child to another. The organism is also found in surface waters used for drinking and recreational purposes. The cyst stage of the organism resists chlorination and can, therefore, pass through municipal supplies that do not also have adequate filtration systems. The cysts reach the surface water supplies through the fecal deposits of beaver and muskrats. When ingested cysts reach the small intestine, trophozoites are released. The trophozoites attach themselves to the intestinal wall by adhesive disks, causing inflammation and irritation of the bowel. This inflammation prompts the influx of fluids, causing a loose stool. As a result, food is malabsorbed. The patient suffers from dehydration. Symptoms usually manifest within one week of eating the contaminated food and consist of nausea, explosive diarrhea (up to 10 movements per day), and fatigue. Without treatment, symptoms linger and re-infection is possible.28
General Biology
Published in Ronald Fayer, Lihua Xiao, Cryptosporidium and Cryptosporidiosis, 2007
Trophozoites contain a prominent nucleolus within a single nucleus surrounded by cytoplasm (Figure 1.6), and a well-developed attachment/feeder organelle. During nuclear division of merogony, division spindles, nuclear plaques, and centrioles have not been observed. After nuclear division, merozoites develop simultaneously around the margin of the meront (syn. schizont). Merozoite anlagen, including a double inner membrane complex, an electron-dense collar, electron-dense granules, a few micronemes, ribosomes, and cytoplasm, form immediately beneath the schizont plasmalemma just above each schizont nucleus. Merozoites remain attached to a residuum at their posterior end and become more elongated during maturation. During this time, a pair of rhoptries, more micronemes, numerous electron-dense granules, and many ribosomes form in the cytoplasm (Figure 1.9). Micronemes often form in rows perpendicular to the long axis of the merozoite (Figure 1.9). Upon maturity, merozoites separate from the residual body, the host-cell membrane surrounding the meront lyses, and merozoites become extracellular (Figure 1.10), able to infect other host cells. Numerous developmental stages including meronts containing fully formed merozoites can be seen in Figures 1.17 and 1.18.
General Biology of Cryptosporidium
Published in J. P. Dubey, C. A. Speer, R. Fayer, Cryptosporidiosis of Man and Animals, 2018
R. Fayer, C. A. Speer, J. P. Dubey
Trophozoites contain an undifferentiated cytoplasm, a well-developed feeder organelle, and a nucleus with a prominent nucleolus (Figure 6). Trophozoites give rise to schizonts or gamonts. Schizonts and microgamonts undergo two to four nuclear divisions preceding merozoite or microgamete formation. Macrogamonts do not undergo nuclear division.
Malaria parasites detection and identification using object detectors based on deep neural networks: a wide comparative analysis
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2023
Maura Rocha, Maíla Claro, Laurindo Neto, Kelson Aires, Vinicius Machado, Rodrigo Veras
The main species of Plasmodium spp that infect humans are as follows: P. malariae, P. ovale, P. falciparum, and P. vivax; the latter two are the most common (Organization et al. 2020). The species differ in shape, infected cells, and morphology of the parasite at some of the life cycle stages (Somasekar et al. 2011). The development stages of the malaria parasite are ring, trophozoite, schizont, and gametocytes. Figure 1 shows blood slides images samples infected by P. vivax in their various life stages.