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Mastigophora (flagellates) Dr. Maysoon A. Merdaw Intestinal flagellates Giardia lamblia also called Giardia duodenalis, is one of the most common intestinal parasites in the world. Life Cycle Cysts are the transmission stage and are excreted in the feces of infected individuals into the environment....

Mastigophora (flagellates) Dr. Maysoon A. Merdaw Intestinal flagellates Giardia lamblia also called Giardia duodenalis, is one of the most common intestinal parasites in the world. Life Cycle Cysts are the transmission stage and are excreted in the feces of infected individuals into the environment. When ingested, exposure to the low pH of the stomach and pancreatic enzymes induces excystation, with 2 troph. developing from each cyst. Troph. attach to epithelial cells of the upper intestine, primarily the jejeunum but also the duodenum, where they grow and divide. Pathogenesis: Giardia lamblia generally does not penetrate the intestinal wall, but may cause inflammation and shortening of the villi in the small intestine. Extremely large numbers of troph. may be present and may lead to a direct, physical blockage of nutrient uptake, especially in fat soluble substances such as vitamin A. Symptoms include severe diarrhea of steatorrhoea type, epigastric pain and flatulence. When the parasite localizes in the biliary tract, it may lead to chronic cholecystitis and jaundice. Laboratory diagnosis: -General Stool Examination (GSE) can identified the cysts in formed stool and the trophozoites in diarrhoeal stool by direct smear under the light microscope. - The enzyme-linked immunosorbent assay (ELISA) to detect anti-Giardia antibodies in patients’ serum. - Entero test (string test): aspirate specimens from the upper intestine by swallow a gelatin capsule, contains a spool of nylon string, to help it go down into stomach then the string will be pulled back up out of stomach through the throat and examined under a microscope. Treatment: ∙ Metronidazole is an antibiotic that can cause nausea. ∙ Tinidazole often treats giardiasis in a single dose and is as effective as metronidazole. ∙ Furazolidone is a popular option for children. Non pathogenic intestinal flagellates Chilomastix mesnili may be confused with other pathogenic species during diagnosis. Inhabit in the human cecum and/or colon. The resistant cyst stage in the life cycle of Chilomastix is responsible for transmission. Both cysts and trophozoites can be found in the feces (diagnostic stages). Genital flagellates Trichomonas vaginalis an extracellular single-cell flagellated parasite, the trophozoite has a characteristic jerky motility. It has 5 flagella—four of which are in the anterior and the other flagellum is incorporated within the undulating membrane. T. vaginalis exists as a troph. lacks a cystic stage and lacks mitochondria, instead Hydrogenosome in metabolism. uses the Life Cycle It is inhabits urogenital the tract human and responsible for trichomoniasis which is consider as one of the important venereal diseases. Pathogenicity Adhesion of T. vaginalis to vaginal epithelial cells is a critical step in pathogenesis. Adhesion proteins, cysteine proteases, and the lipophosphoglycan (LPG) play distinct roles in the pathogenesis and evasion of host immunity. Adhesion is time, temperature, and pH dependent. There are also 2 species of trichomonads infect human beings, T.tenax in the oral cavity, Pentatrichomonas hominis in the intestinal tract. Symptoms may not appear for up to six months, the signs and symptoms of trichomoniasis in females include: vaginal discharge, irritation, dysuria, low abdominal discomfort. The infected males are usually asymptomatic, acting as carriers of infection. It can cause dysuria and may increase incidence and risk of aggressive prostate cancers when there is prolonged infection within the prostate. Laboratory diagnosis: The diagnosis of T. vaginalis cannot be readily made solely on the classic symptoms, because the clinical symptoms may be synonymous with those of other Sexual Transmitted Diseases (STDs). Diagnosis of trichomoniasis by microscopic examination considered most traditionally method. Also can be diagnosed by culturing the exudates on media. Treatment: nitroimidazole antibiotics (e.g., metronidazole or tinidazole). Although treatment is available, most cases occur in developing countries, where accessing healthcare is difficult and facilities are limited, studies indicate that without antimicrobial treatment women may maintain chronic infections.