Parasitology for Technologists (1) TL 202 Lecture Notes PDF

Department of Microbiology & Immunology Parasitology for technologists (1) TL 202 By Dr. Selwan Hamed Aboelnaga PhD In Pharmaceutical Sciences (Microbiology & Immunology) From Faculty of Pharmacy - Helwan University and UIU...

Department of Microbiology & Immunology Parasitology for technologists (1) TL 202 By Dr. Selwan Hamed Aboelnaga PhD In Pharmaceutical Sciences (Microbiology & Immunology) From Faculty of Pharmacy - Helwan University and UIUC (University of Illinois at Urbana-Champaign) – Illinois – USA  Parasites may be divided into two main groups (according to general characters): 1) Protozoa: Microscopic, unicellular, eukaryotic, motile organisms that lack photosynthetic capability. 2) Metazoa: Macroscopic, multicellular organisms. 1) Protozoa  1) Classification based on Motility: Pseudopods Flagellates Ciliates  Protozoa 2) According to site of infection: They could be classified into : A) Intestinal –urogenital protozoa. B) Blood and tissue protozoa.  A) Intestinal –urogenital protozoa. - Protozoa may colonize and infect the duodenum , small bowel, colon, and urogenital tract of humans. -These organisms are transmitted by the fecal-oral route.  A) Intestinal –urogenital protozoa. 1. Amoebae The amoebae are primitive unicellular organisms.  A) Intestinal –urogenital protozoa. Their life cycle is relatively simple and divided into two stages: The actively motile feeding stage (trophozoite). The quiescent, resistant, infective stage (cyst). Most amoebae found in humans are commensal organism (Entamoeba coli, Entamoeba hartmanni, Entamoeba gingivalis). However, Entamoeba histolytica is an important human pathogen.  Entamoeba histolytica vs Entamoeba coli Number of nucleus, site of karyosome, pseudopos Entamoeba histolytica Entamoeba coli  Entamoeba histolytica vs Entamoeba coli Number of nucleus, site of karyosome, pseudopos Entamoeba histolytica Central karyosome. Cyst (4 nucleus) Trophozoite have finger like pseudopod.  Entamoeba histolytica vs Entamoeba coli Number of nucleus, site of karyosome, pseudopos Entamoeba coli Eccentric karyosome. Cyst (> 4 nucleus) Trophozoite have granular pseudopod. Life cycle  Clinical syndrome 3 phases of the disease: 1. Intestinal amoebiasis. 2. Chronic carrier. ‫حامل للمرض‬ 3. Extraintestinal amoebiasis.  Clinical syndrome 1. Intestinal amoebiasis: a- Symptoms include abdominal pain, cramping, and colitis with diarrhea. b- More severe disease is characterized by numerous stools per day with blood and mucous (amoebic dysentery). ‫دوسنتاراي أميبية‬ Differentiation between amoebic & bacillary dysentery stool  Clinical syndrome 2. Chronic Carrier: In many cases, the trophozoites remain confined to the intestinal lumen (noninvasive infection) of individuals who are asymptomatic carriers, passing cysts in their stool.  Clinical syndrome 3. Extraintestinal amoebiasis: a- Systemic signs of infection (fever, leukocytosis, rigors) are present. b- The liver is primarily involved leading to (amoebic hepatitis).  Laboratory Diagnosis 1. Cyst and trophozoite forms of E. histolytica are detected in fecal specimens from infected patients. 2. In freshly passed stools actively motile trophozoite can be seen, whereas in formed stools the cysts are usually the only form recognized with dead trophozoites.  Laboratory Diagnosis 3. Extraintestinal amebiasis is sometimes diagnosed using scanning procedures for the liver and other organs. 4. Specific serologic tests, together with microscopic examination of the abscess material, can confirm the diagnosis.  Treatment A. Acute amoebic dysentery: 1. Dehydration and electrolyte disturbances have to be corrected through either oral or parenteral routes. 2. Abdominal cramps and diarrhea are controlled by antispasmodics. 3. Specific treatment: Metronidazole or Tinidazole  4. It is necessary to repeat the stool examination 6 months after treatment to confirm total eradication of the organism.  Free-living amoebae 1- Acanthamoeba Acanthamoeba, and other free-living amoebae are found in soil and in contaminated tap water, sewer systems, soil, swimming pools, hot tubs and saunas. Most human infections with these amoebae are acquired during the warm summer months by individuals exposed to the amoebae while swimming in contaminated waters.  Inhalation of cysts present in dust may account for some infections, whereas ocular infections with Acanthamoeba are associated with contamination of contact lenses with non-sterile cleaning solutions.  Free-living amoebae 2- Naegleria ( Brain eating amoebae) In all thermal pools keep your head above water to avoid the possibility of developing the serious illness called amoebic meningitis. This disease can be caught in thermal pools if water (contaminated with Naegleria) enters the nose while swimming or diving.  Self study For Giardia duodenalis  A) Intestinal –urogenital protozoa. 2-Flagellates The flagellates of clinical significance include: Giardia duodenalis and Trichomonas vaginalis. Giardia has both cyst and trophozoite stages in its life cycle. In contrast, no cyst stage has been observed for Trichomonas.  1) Giardia duodenalis (G. lamblia; G. intestinalis) Giardiasis Life cycle  Cysts are resistant forms and are responsible for transmission of giardiasis. Both cysts and trophozoites can be found in the feces (diagnostic stages). The cysts are hardy and can survive several months in cold water. Infection occurs by the ingestion of cysts in contaminated water, food, or by the fecal-oral route (hands or fomites). In the small intestine, excystation releases trophozoites (each cyst produces two trophozoites). Trophozoites multiply by longitudinal binary fission, remaining in the lumen of the proximal small bowel where they can be free or attached to the mucosa by a ventral sucking disk. Encystation occurs as the parasites transit toward the colon. The cyst is the stage found most commonly in nondiarrheal feces. Because the cysts are infectious when passed in the stool or shortly afterward, person-to-person transmission is possible. Complete the above table for Giardia Thanks