الدكتورة زينب خالد خليل ماجستير احياء مجهرية MEDICAL PARASITOLOGY . طفيليات عملي ثالث طب 4 / 10 / 2016 الدكتورة زينب خالد خليل

Entamoeba coli : Morphology Trophozoite: 1- Its size (10-35 µm), it has granular endoplasm containing ingested bacteria and debris (no RBCs) .

. 2. The ectoplasm is not clear. and it has small pseudopodia. 3. It has one nucleous contain large eccentric kariosome, and large chromatin granules arrenged irregularly beneath nuclear membrane. .

The cyst : is large oval in shape , 10 – 30 µm and it has 1 - 8 nucli, the characters just like that of trophozoite.

Amoebas species which parasites human being are : Amebas include many free-living and parasitic amebas.The most important species which parasites human being are : 1- Entamoeba histolytica. 2- E.coli. 3- E.gingivalis . 4- Dientamoeba fraglis. 5- Endolimax nana . 6- Iodoamoeba butschlii . 7- Other amoebas infecting human are morphologically very simillar to E.histolytica, e.g, E.hartmanni , E.dispar. & E.polecki . 8- Free living amoebas are Negleria & Acanthameba are accidental parasites of human being . The majority of these amoeba are non-pathogenic commensal parasites, or only cause mild disease. E.histolytica can cause sever infection & can become a highly virulent and invasive parasite that causes a lethal systemic disease . So the identification of E.histolytica requires differentiation from other parasites wich are mentioned above.

2. The ectoplasm is not clear. and it has small pseudopodia. 3. It has one nucleous contain large eccentric kariosome, and large chromatin granules arrenged irregularly beneath nuclear membrane. The cyst is large oval in shape and it has 8 nucleous, the characters just like that of trophozoite.

Habitate Large intestinal lumen

ENTAMOEBA HISTOLYTICA 8

Morphology ( Trophozoite ): 1- Its size (12-30 µm), Clear ectoplasm . 2- Large finger – like pseudopdia 3- The endoplasm is granular and may contain RBCs. 4- It has one nucleous, contain small central keryosome and fine chromatin granules arranged regularly beneath nuclear membrane.

Morphology ( mature cyst) : 1- Small (10 – 20 µm) , spherical in shape, smaller than that of E. coli, containing 1 - 4 nuclei is usually found in feces . Each nucleus contain similar nuclear morphology like the trophozoite.

Life cycle of E. histolytica:   Infection by E. histolytica occurs by ingestion of mature cysts in fecally contaminated food, water, or hands.  Excystation occurs in the small intestine and trophozoites are released which migrate to the large intestine.  The trophozoites multiply by binary fission and produce cysts , which are passed in the feces .

Because of the protection conferred by their walls, the cysts can survive days to-weeks in the external environment and are responsible for ttransmission. Trophozoites can also be passed in diarrheal stools, but are rapidly destroyed once outside the body, and if ingested rapidly destroyed by gastric juice.   In many cases, the trophozoites remain in intestinal lumen as noninvasive infection of individuals who

are asymptomatic carriers, passing cysts in their stool only are asymptomatic carriers, passing cysts in their stool only.  In some patients the trophozoites invade the intestinal mucosa and cause intestinal disease or developed perforated ulcer and the trophozoites migrate through the blood stream to invade the extraintestinal organs such as the liver, brain, and lungs and it will cause amoebic infection in these organs.

Life cycle of E. histolytica:  

Habitate: Wall of L.I :cecum & sigmoidorectal region.

Mode of transmission : 1. Mature cyst in the feces of chronic patients or asymptomatic carrier . 2. Contaminated food, drinks, vegetables or hands with infective cysts. 3. Flise (House fly) play an important roles in trasnmission of these cysts to the food of human .

Diagnosis of Amoebiasis : Lab. Stool examination: 1- Stool of patient should be examined by : a- Direct method with saline for motile trophozoite . A drop of N.S is mixed with drop of stool on a clean slide and covered by coverslip then examined microscopically. b- Iodin staining of stool sample as above with adding a drop of iodin stain and microscopically examined for cysts of E.histolytica . c- The typical amoebic stool is contain blood, mucous , few WBC & Bacteria .

2- Culture of stool. Other methods: 3- Sigmoidoscopy may reveal the charecteristic flask-shaped ulcers especially in sever cases .

4- Biopsy & fluid :for trophozoites . 5- Serology, is very important for the diagnosis of extraintestinal amoebiasis e,g, Indirect haemagglutination (IHA) & Polymirase Chain Reaction (PCR test) .

6- Ultrasound, CTscan, MRI can be used to detect hepatic abscesses .

Balantidium coli

Trophozoite morphology 50-150 mic Cilliated parasite Oval shape Greenish yellow color Kidney or bean shape Macronucleus Small micronucleus Retractile food vacule

Cyst morphology 45-55 mic Spherical shape Cyst wall is thick consist of 1-2 layers No phagosome Macronucleus Conractile vacules No cilia

Life cycle Infection is happened by consumption of material contaminated with feces of some farm animals cotaining cyst (the infective stage). Cyst exyst in the small intestine releasing trophozoites that migrate to the large intestine. Trophozoites reside in the lumen of large intestine Invade mucosa and sub M. Feed on mucosal cells, RBC, leukocyte where they divide by transverse binary fission. Encystation is triggered by dehydration of intestinal content.

Life cycle

Habitate *Parasite live in L.I specially cecal region *Cyst formed in large intestine or in outer envirnment

Diagnosis History Symptoms Clinical signs could confused by histolytica infection Finding the typical trophozoites and cysts in the stool

Diagnosis cont….. Finding parasite (cyst or trophozoite) in stool by Direct wet mount method Stained smear by iodin

*Direct Wet Mount Preparation method: All stool samples should be subjected to direct microscopic examination in order to detect the presence of protozoan trophozoites, cysts, and especially to illustrate trophozoites . Method: A drop of normal saline placed on the middle of a clean slide. A small portion of stool sample mixed with the drop of saline by wooden stick. The mixture covered with cover- slip. The slide examined using light microscope.  

Iodine staining method: This method mainly used to clarify morphological details of the protozoan parasite. Cyst can be specifically identified in this mount. The procedure is carried out as following: Wet smear of stool sample directly prepared by mixing drop of normal saline and stool on a clean microscopic slide. A drop of iodine placed on the preparation, then covered with a cover- slip. The slides examined with light microscope using different objective lens powers.