Coccidia

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Coccidia Aims : Human coccidiosis is produced by species of Isospora; is more important in immunocompromised patients like (AIDS,and kidney transplant patients), and in malnourished children. Obejectives: 1.Scientific classification 2. What are coccidia? 3. What is Coccidiosis ? 4. General characteristic of the Coccidia : 5. Isospora belli 1.Scientific classification Phylum:Apicomplexa Class: Sporozoea Subclass:Coccidia 2.What are coccidia? Coccidia are small protozoans (one-celled organisms) ,
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    Coccidia   Aims : Human coccidiosis is produced by species of    Isospora;  is more important inimmunocompromised patients like (AIDS,and kidney transplant patients), andin malnourished children.   Obejectives: 1.Scientific classification2. What are coccidia?3. What is Coccidiosis ?   4.   General characteristic of the Coccidia :   5.  Isospora belli 1.Scientific classification   Phylum:Apicomplexa   Class: Sporozoea   Subclass:Coccidia2.What are coccidia?Coccidia are small protozoans (one-celled organisms) , which are members of the classSporozoa ,an exclusively parasitic group that typically requires alternation of sexual andasexual reproduction in the life cycle.   Some worker believe it is a yeast; however, until its taxonomic position and life cycleare more completely known, it can be regarded as a protozoan   3.What is Coccidiosis ?   Coccidiosis is the disease caused by coccidian infection. Coccidiosis is a parasiticdisease of the intestinal tract of humans and other animals, caused by coccidianprotozoa.   Coccidian organisms can infect a wide variety of animals, including humans , birds,and livestock, they are usually species-specific. One well-known exception istoxoplasmosis, caused by Toxoplasma gondii .   People often first encounter coccidia when they acquire a young puppy or kitten who isinfected. The infectious organisms are canine/feline-specific and are not contagious tohumans (compare to zoonotic diseases). The species of medical importance is found in subclass Coccidia andcause disease of human include one of the following genera: 1.Genus  Isospora .2.Genus Cryptosporidium .3.Genus Toxoplasma .4.Genus Plasmodium.  5.Genus Sarcocystis.  The term Coccidia is also applied for immature oocyct of   Isospora and  Eimeria genera . After the maturation of these oocyst which is found in fecal specimen of    vertebrates(mammals, birds). In lab. by using 2.5% potassium dichromate solution,these mature oocyst is either :a.   If contain 2 sporocyst each one with four sporozoites(these oocyst belong toGenus  Isospora ).b.   If contain 4 sporocyst each one with 2 sporozoites(these oocyst belong toGenus  Eimeria   4.General characteristic of the Coccidia :1.   Locomotive organelles absent, the flagella present only in male gamete. 2.   Life cycles are complex, with well-developed a sexual(which producemerozoites , some of these merozoites differentiate into macro andmicrogametes) and sexual stages (which produce oocysts) . 3.   Sporozoa produce special spore like cells called sporozoites. 4.   It is intracellular parasite with complex cycle alternating between humans andmosquitoes as in malaria ,while in T.gondii which causes an acute infection inhuman is acquired from cats and other animals. 5.   Have similar independent gametocytes ,the male or microgametocyte andfemale or macrogametocyte. The female produce a single macrogamete andthe male produce multiple gametes , followling an oocyst is formed afterfertilization. 6.   The oocyst in species of   Isospora and Sarcocyst  is produces two internalsprocysts, each with four sporozoites ,in Cryptosporidium the sporocyst stageis omitted. 7.   Only two species of coccidian are known to undergo shizogony andgametogony in man  Isospora belli and Cryptosporidium muris .  Isospora belli : It is the only species of   Isospora that infect man, although large no. of   Isospora  species infect mammals, birds &other vertebrates hosts.  Isospora belli is a coccidian protozoan that infects humans and some primates.This species was first recorded in 1915 by Dr. H.M. Woodcock when he observedcoccidian oocysts in the feces of World War I soldiers overseas. Since then  I. belli  has been studied as the causal agent in the intestinal disease  Isosporiasis . This  protozoan is frequently responsible for the phenomenon known as “traveler’s  Eimeria oocyst  Isospora oocyst    diarrhea.”  I. belli is found throughout the world but is more common in tropicaland subtropical locations. It is the least common of the three coccidian parasitesthat infect human intestines( Cryptosporidium , Toxoplasma ,& Isospora ). Disease:   The disease caused by  I.belli is called intestinal Coccidiasis orCoccidiasis belli or Isosporiasis .This disease is typically mild in healthy individuals but can be life threatening inpeople who are young or immunodepressed.  Isosporiasis was largely ignored untilits recent emergence as one of the opportunistic infections affecting AIDSpatients. Mode of transmission :  Isosporiasis is usually transmitted through ingestion of sporulated oocysts fromcontaminated food and water . However , because isosporiasis is frequently seenin homosexuals than in the general population, it is suggested that sexualtransmission, especially through oral-anal sexual practice, may have an importantrole in the group. Morphology:    Isospora belli Immature Oocyst Containing One Sporoblast From CDC The stage found in freshly stool is the immature oocyst , the shape is elongated,ovoid &flask shape(like a bottle with short neck).It has two membranes outer andinner ,they are hyaline ,transparent &colorless and the tip of narrow end, there ismicropyle. Within the oocyst there is sporoblast(zygote)with nucleus. Aftermaturation in the feces within 2-3 days or in 2.5% potassium dichromate solution,the mature oocyst contain two spherical sporocyst, each with four crescent(banana shaped)sporozoites, whichit is the infective stage of the parasite. The mature cyst of   I.belli    Life cycle of   I. belli : It include 2 cycles : asexual or schizongony& followed by sexual or gametogonycycle& all the two cycle take place in the intestinal epithelium cell of man.Infection is by ingestion of food contaminated with mature oocyst & by theaction of digestive enzymes of GIT, the oocystic and sporocystic wall will rupturereleasing the sporozoites , and the latter will enter the epithelium lining of smallintestine and grow to become trophozoite , the nucleus and cytoplasm will dividedinto large numbers of merozoites which develop through the schizogony cycleagain,after 2-3 cycles some of these merozoites will enter epithelium cell to formmacrogametocytes( ♀ ) and microgametocytes (♂) through the gametogony cycle .Only one gamete of male will fertilize one female gamete , after fertilization , azygote is formed within the lumen of S.I. and secret a wall around it to formimmature oocyst that will pass with feces outside to be mature oocyst which isready to infect another man, and the life cycle is completed.Both asexual and sexual life cycles takes place in man in the same host. Theclinical course of Isosporiasis may be protected by repetition of intracellularasexual cycle inside the host .
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