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Intestinal and Luminal Flagellates and Ciliates. Morphology of G. lamblia.
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Intestinal and Luminal Flagellates and Ciliates
Morphology of G. lamblia • Giardia lamblia (synonymous with Lamblia intestinalis and Giardia duodenalis) is a flagellatedprotozoanparasite that colonises and reproduces in the small intestine, causing giardiasis. The giardia parasite attaches to the epithelium by a ventral adhesive disc, and reproduces via binary fission. Giardiasis does not spread via the bloodstream, nor does it spread to other parts of the gastro-intestinal tract, but remains confined to the lumen of the small intestine Giardia trophozoites absorb their nutrients from the lumen of the small intestine, and are anaerobes. If the organism is split and stained, it has a very characteristic pattern that resembles a familiar "smiley face" symbol
Intestinal and Luminal Protozoa • Giardia Lamblia • Giardiasis, lambialiasis • Trophozoite is a bilaterally symmetrical, pear-shaped flagellate, 12 to 15 micro with a broad rounded anterior and a tapering posterior extremity.
Symptomatology • Colonization of the gut results in inflammation and villous atrophy, reducing the gut's absorptive capability. In humans, infection is symptomatic only about 50% of the time, and protocol for treating asymptomatic individuals is controversial.
Symptomatology • Symptoms of infection include (in order of frequency) diarrhea, malaise, excessive gas (often flatulence or a foul or sulphuric-tasting belch, which has been known to be so nauseating in taste that it can cause the infected person to vomit), steatorrhoea (pale, foul smelling, greasy stools), epigastric pain, bloating, nausea, diminished interest in food, possible (but rare) vomiting which is often violent, and weight loss
Symptomatology • Pus, mucus and blood are not commonly present in the stool. It usually causes "explosive diarrhea" and while unpleasant, is not fatal. In healthy individuals, the condition is usually self-limiting, although the infection can be prolonged in patients who are immunocompromised, or who have decreased gastric acid secretion.
Diagnosis • Diagnosis is usually made by finding cysts in formed stools and trophozoites and cysts in diarrheic feces. • Prevention: Avoid eating contaminated food especially vegetables and water. • Flies carrying the cysts should not be allwed to alight on your food
Balantidium Coli • Diseases. Balantidiasis, balantidiosis, balantidial dysentery. • Morphology and Physiology • B.coli is the largest intestinal protozoan of humans and the only pathogenic ciliate. • Grayish green, unstained. • Ovoid trophozoite and shaped like a sac. • Enclosed in a delicate protective pellicle covered with spiral longitudinal rows of cilia. • Life Cycle • The life cycle of B.coli is similar to that of E. histolitica, except that there is no multiplication of Cyst. • Cyst are infective worms.
Balantidium coli Cysts and Trophozoites
Mode of Infection Infection occurs when a host ingests a cyst, which usually happens during the consumption of contaminated water or food. Once the cyst is ingested, it passes through the host’s digestive system.While the cyst receives some protection from degradation by the acidic environment of the stomach through the use of its outer wall, it is likely to be destroyed at a pH lower than 5, allowing it to survive easier in the stomachs of malnourished individuals who have less stomach acid.In the lumen trophozoites may disintegrate or undergo encystation.
Mode of Infection • Once the cyst reaches the small intestine, trophozoites are produced.The trophozoites then colonize the large intestine, where they live in the lumen and feed on the intestinal flora.Some trophozoites invade the wall of the colon using proteolytic enzymes and multiply, and some of them return to the lumen.
Mode of Infection • Encystation is triggered by dehydration of the intestinal contents and usually occurs in the distal large intestine, but may also occur outside of the host in feces. Now in its mature cyst form, cysts are released into the environment where they can go on to infect a new host.
Epidemiology • Incidence of B. coli in humans is very low, it is higher on hogs. • Former is infectious on humans, while the latter, the more common species, apparently dos not affect humans. • Pathology and Symptomatology • The mucosa and submucosa of the large intestine are invaded and destroyed by the multiplying organisms. • Diagnosis • Diagnosis depends upon the identification of trophozoites in diarrheic stools and less cysts.
TRICHOMONAS VAGINALIS This is a small protozoan parasitizing the human vagina, prostate and urethra. It cause little or no discomfort in men, but it often produces considerable inflammation and irritation in women. The disease is readily transmittable, sexually and through contact with toilet seats and towel.
Epidemiology • The incidence of infection is about 10-25% percent in women. • It is higher in groups in which feminine hygiene is deficient. Pathology and Symptomatology • Causative agent of a persistent vaginitis. • Flagellate is responsible for a low-grade inflammation. Diagnosis • Clinical diagnosis is based on symptoms of burning, a frothy creamy discharge, and punctuate lesions and hyperemia of the vagina.
Prevention • Attention to personal hygiene is the most important preventive measure. • The detection and treatment of infected males should help in reducing infections.
Coccidia Toxoplasma gandii • T. gandii was first found in the african rodent ctenodactylus gandii. Morphology • The actively multiplying asexual form in the human host is an obligate, intracellular parasite, pyriform in shape and approximately 3 by 6 micro units. • This parasite is called tachyzoite. Life Cycle • It multiplies within the host cells by a specialized form of division called endodyogeny, in which 2 daughter cells are formed within a mother cell.
Epidemiology • Toxoplasmosis is cosmopolitan, and antibody surveys indicate that from 20 to 75% of various populations are chronically but asymptomatically infected. Pathology and Symptomatology • Relatively benign, well-adapted parasite and its disease-producing properties have been attributed to virulent strains, especially susceptible hosts or the site of the parasite. Diagnosis • Serelogic tests are very important in the diagnosis of taxopalsmosis. • Diagnosis by Serologic means requires demonstration of a significant increase in antibody titers
Life cycle of Toxoplasma gondii Prevention • Thorough cooking of all meats and careful attention to cat feces.
Isospora belli Morphology • The oocysts, which are the forms found in the stool, are elongated or ovoid and 25-33 micro units by 12-16 micro units in size. Pathology and Symptomology • Pathogenicity is variable; excretion of oocysts has been observed in apparently healthy individuals as well as in those in diarhea. Diagnosis • Diagnosis is made by demonstrating oocysts in the feces, oocysts and or sporocysts in duodenal contents and intracellular stages of the parasite.
