Giardia Lamblia Past Paper PDF

Flagellates Awad alla Hamza Osman Flagellates  Intestinal flagellates Giardia lamblia (pathogenic) Trichomonas hominis Chilomastix mesnilli  Urogenital flagellates Trichomonas vaginalis  Blood and tissue flagellates Trypanosome Lieshmania Giardia  Giar...

Flagellates Awad alla Hamza Osman Flagellates  Intestinal flagellates Giardia lamblia (pathogenic) Trichomonas hominis Chilomastix mesnilli  Urogenital flagellates Trichomonas vaginalis  Blood and tissue flagellates Trypanosome Lieshmania Giardia  Giardia: Description Human pathogen: G. lamblia or G. intestinalis or G. duodenalis was first observed in 1681 by Anton van Leeuwenhoek in his own diarrheal stools. The parasite was named in 1915 for two scientists who studied it: Prof. Giard in Paris and Dr. Lambl A flagellated protozoan enteric parasite. Two life stages: trophozoite and cyst.  Giardia: Description Causes : Giardiasis in man especially children. Geog. Distribution: international. Habitat : duodenum, upper part of small intestine, bile ducts and gall bladder as trophozoites attached to the mucosa. Infective stage : the cyst. Infection occurs by the ingestion of mature cysts in contaminated water, food ( fecal-oral route)  Morphology of Trophozoite stage Pear shaped, rounded anterior end, posterior end pointed (looks like monkey face) Size: 12 to 15 μm long x 5 to 9 μm wide Dorsal surface convex, ventral surface concave Ventral surface bears sucking disk to adhere to surface of intestinal cell  Morphology of Trophozoite stage Bilaterally symetrical: 2 nuclei, 2 axostyles, 4 pairs of flagella (2 anterior, 2 posterior, 2 ventral, and 2 caudal) actively moving (similar to a falling leaf) and feeding stage – Habitat: small intestine – May invade the common bile duct.  Morphology of Trophozoite stage Nuclei Sucker Median body Front side flagella Behind side flagella ventral flagella Tail flagella Ventral surface Lateral surface  Morphology of Trophozoite stage ventral dorsal Scanning EM view of trophozoite surface showing the adhesive disk  Morphology of Trophozoite stage Light microscope photos of trophozoites Morphology of Giardia lamblia cyst ovoid in shape - 8-12 μm long x 7-10 μm wide - thick cyst wall 4 nuclei present, either clustered at one end or present in pairs at opposite ends Cyst may remain viable in the external environment usually water) for many months. Morphology of Giardia lamblia cyst Morphology of Giardia lamblia cyst Light microscope photos of cysts Giardia lamblia Vital Cycle Int.grosso Int.delgado  G. lamblia life cycle Infection initiated by the ingestion of infectious cysts Acid in the stomach stimulates the release of trophozoites from the cyst (Excystation) Trophozoites are released in the duodenum and jejunum (upper part of small intestines) where they multiply by binary fission Trophozoites attach to the intestinal villi by means of a sucking disk  G. lamblia life cycle Trophozoites can develop into cysts for survival outside of the host (Encystation occurs as the parasites transit toward the colon). Trophozoites cause an explosive diarrhea such that cysts are released into the environment Trophozoites remain in the G-I tract and almost never found elsewhere in the body.  Life Cycle of Giardia inside human body Pass in stool cyst Binary fission Enter with food trophozoite Duodenal mucosa G. lamblia life cycle  Pathogenesis Mechanism of Disease development:- 1- Mechanical irritation inflammation “Duodenitis” (mild illness) 2- Enterotoxin stimulate cytokine production inflammatory response (play an important role in production of Inflammation & Diarrhea that may be mild or severe  Pathogenesis 3- Blunting of brush border Atrophy of villi 4- Malabsorption syndrome Malnourishment (due to interference with absorption – Atrophy of the villi)  CLINICAL MANIFESTATIONS  Range from none abdominal pain causing acute or chronic diarrhea nausea, and vomiting  Gray, greasy, voluminous malodorous diarrhea!  Giardia trophs are attracted to bile salts: so this result in infections of bile ducts and gall bladder, causing jaundice.  CLINICAL MANIFESTATIONS Nutrient malabsorption and physical blockage and damage to microvilli. Leads to: Fat Malabsorption---- greasy stool STEATORRHEA (fatty stools; fat in stools) Carbohydrate fermentation by bacterial flora ---- gas production Accumulation of electrolytes ----- increase water content in intest. lumen  Diagnosis Direct stool examination Nylon string Trophozoite in diarrhoeic stool Cysts in formed stool Trophs in duodenal Enterotest. Serological tests: Treatment:  Treatment Metronidazole OR Tinidazole Recently Albendazole.  Prevention Food and water must be protected from feces contamination by flies Food and drinking water must be cooked and boiled Human feces should not be used as fertilizer Personal hygiene: wash hands after defecation and before meals.  Differences between G lamblia &non pathogenic flagellates G. lamblia T. hominis C. mesnili 10-12um 7-15um 10-20um size Twists & rotates Jerky Rotary movement (falling leaf) Pear shaped Oval to round Pointed tail features 2nuclei 4anterior flagella 3anterior flagella 8 flagella Axostyle Spiral groove axonemes Undulating membrane One nucleus One nucleus cytostome C. mesnili G. lamblia T. hominis  Trichomonas tenax – Habitat is in the mouth; sockets of teeth; gums. – Transmitted orally (kissing; sharing food eating or drinking tools).  Trichomonas tenax (Trophozoites) Oval to pear 5 to 14 μm long Undulating membrane extending 2/3 of body length Thick axostyle five flagella at the anterior end.  Clinical symptoms The typical Trichomonas tenax infection does not produce any notable symptoms. On a rare occasion, T. tenax has been known to invade the respiratory tract Laboratory diagnosis The specimen of choice for diagnosing Trichomonas tenax trophozoite is mouth scrapings. Trichomonas vaginalis  Trichomonas vaginalis Disease: Trichomoniasis Trichomonas vaginalis inhabits in the vagina of women, urethra in both sex, and prostate of men. Worldwide in distribution Transmission is by contact (by sexual intercourse). Sometimes, by indirect contact, such as sharing damp wash clothes / swimming clothes.  Morphology (trophozoite) Pear-like (teardrop), 7~32 X 5~12μm One nucleus and a axostyle projected posterior out of the body. Undulating membrane on one side (one- third the length of the body). Basal body on anterior to nucleus and produce 4 anterior flagella and 1 posterior flagellum.  Life cycle Only trophozoite stage in life cycle. Women: vagina and urethra Trophozoite Men: urethra or prostate, testes, The infection is acquired by sexual activity or some indirect ways Only trophozoites in life cycle, no cyst stage The infective stage is trophozoite The trophozoites multiply by binary fission  Pathogenesis The normal pH of the vagina is 4~4.5 and it is maintain by the activity of lactic acid-producing bacteria. When T. vaginalis live in the vagina, T.vaginalis can disrupt lactic acid-producing bacteria, causing the pH to rise above 5. The pathogenic bacteria survive in the vagina and developed fast. Inflammation or vaginitis.  Clinical features The incubation period is 5~28 days. In women, vaginitis with purulent discharge is prominent symptom, be accompanied by vulva and cervical lesions, abdominal pain, dysuria. In men, asymptomatic (common) ; urethritis and prostatitis (occasional)  Diagnosis 1-Specimens:  From female: urine, vaginal swap, or urethral discharge.  From male: urine, urethral discharge. or prostate secretions. 2-Lab diagnosis:  Examination of vaginal discharge and vaginal scraping (swap).  Examination of urine sediment after centrifugation.  Stained smear.  Culture.