Medical Parasitology

1. Department of Medical Parasitology Medical Parasitology

2. Case analysis Male, 45 years. He Have Felt epigastrium ache since may 1989，also had cough、expectoration 、blood-stained sputum occasionally，night sweat 、emaciation. Physical examination ：hepatomegaly ；X-ray showed: pleural effusion ，primary diagnosis-lung cancer. But there were no lung cancer cells were found in his phlegm except a smallparasite. What is it ?

3. Amoeba Phylum Sarcomastigophora Class Sarcodina/Archamoebae Order amoedida Most of them are free-living normally, except a few are parasitiic life . There is pseudopod in trophozoite. At least seven species of amoebae are known to parasitize human. Entamoeba histolytica is the only known species to cause diseases in human.

4. Amoeba which parasitize in human Name of parasitesparasitic site Entamoeba histolytica enteric cavity Entamoeba hartmanni enteric cavity Entamoeba coli enteric cavity Iodamoeba butscblii enteric cavity Entamoeba nana enteric cavity Entamoeba dispar enteric cavity Entamoeba gingivalis mouth Acanthamoeba ★ comea,brain Naegleria fowleri★ brain ★ free living pathogenic amebic ，occasionally are living in human

6. Entamoeba histolytica

7. Classification Phylum Sarcomastigophora Class Lobosea Order Amoebida Family Endolimax

8. Parasitize in colon and cause amoebic dysentery and all kinds of amoebiasis The morbidity is about 50 million / year and mortality is about 50000 /year that only lower than Japanese schistosomiasis and malaria.

9. Morphology

10. Trophozoite 1. Trophozoite within the lumen （small trophozoite）：enteric cavity，can not engulf RBC 2 Trophozoite within the organization （big trophozoite)：tissues，engulfed RBC(differ to other Amoeba living in human） Cyst: containing 1--4 nucleus; include 4 nucleus when cyst goes into matured

11. nucleu Food Vacuole Red blood cell pseudopod exoplasm endoplasm Nourishing body within the organization vesicular nucleus Trophozoite nourishing body within the lumen

12. pseudopod Trophozoite within the tissue iron hematoxylin stain

13. nucleu Red blood cell pseudopod Trophozoite within the organization 活体

14. pseudopod Active trophozoite within the lumen

15. clubbed chromatoid body Cyst—2 nucleus Cyst-single nucleu glycogen vacuole Mature cyst chromatoid body and glycogen vacuole disappear

16. vesicular nucleus cyst (iodine staining)

17. Life cycle

19. Cysts and trophozoites are passed in feces . Cysts are typically found in formed stool, whereas trophozoites are typically found in diarrheal stool. Infection by Entamoeba 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 , and both stages 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 transmission. Trophozoites passed in the stool are rapidly destroyed once outside the body, and if ingested would not survive exposure to the gastric environment. In many cases, the trophozoites remain confined to the intestinal lumen ( : noninvasive infection) of individuals who are asymptomatic carriers, passing cysts in their stool. In some patients the trophozoites invade the intestinal mucosa ( : intestinal disease), or, through the bloodstream, extraintestinal sites such as the liver, brain, and lungs ( : extraintestinal disease), with resultant pathologic manifestations. It has been established that the invasive and noninvasive forms represent two separate species, respectively E. histolytica and E. dispar. These two species are morphologically indistinguishable unless E. histolytica is observed with ingested red blood cells (erythrophagocystosis). Transmission can also occur through exposure to fecal matter during sexual contact (in which case not only cysts, but also trophozoites could prove infective).

20. Process of life cycle Trophozoite within the lumen (4 nucleus）cyst cyst Penetrates into intestinal wall Goes into enteric cavity Trophozoite within the Tissue

21. 1. process in enteric cavity （1）infective stage：4-nucleus cyst； infective route：mouth infective pattern：drink or ate the food &water contaminated by cysts。 （2）excystation： site——Under the small intestine conditions—— alkaline digestive juice

22. （3）Parasitizestage： (nutrition ？ casing slime in host ,bacterial、 digested food）。 location： colon cavity Trophozoite within the lumen （4） encystation ：location——Under section of colon conditions——nutrition decreasing water decreasing Feces molding （5）shedding stage：cyst。 shedding pattern：company with feces。 Reproductive System ： bipartition

23. 2. process in tissues (pathogenic process)： Trophozoite within the tissue Reproductive System ： bipartition （3）shedding： （ bloody purulent stool ） Trophozoite within the organization nourishing body within the lumen （1） Parasitizestage : location：colon（ ileocecus et al）、 liver、lung、brain、skinand Urinary and genital tract

24. Pathogenesis

25. 2. mechanism： contact lysis relate to the toxin of the parasite and the immunity of host （1）divided into 2 different strains： according the isozyme A．Strain have toxin（pathogenic strain） Ⅱ Ⅵ Ⅶ Ⅺ ⅩⅣ ⅩⅩ strong invasiveness ，adhere、killing、 phagocytose B．Strain without toxin（non-pathogenic strain） Ⅰ Ⅲ Ⅳ Ⅴ Ⅷ Ⅸ Ⅹ 1. stage： Trophozoite within the tissues

26. invasiveness :3 relative factor Galactose/ Acetyl amino lectin Amoeba perforation protein Cysteine protease

27. （2）the environment of intestine ： synergistic effect of the bacterial of intstine （3）Immunity of host： immunity----

28. （2） symptomatic patients（10 ±%） A.Intestinal amoebiasis : Amoebic colitis: （ amebic dysentery 、 amebic granuloma ） B．Extraintestinal amoebiasis: hepatic amebiasis 、 pulmonaryamebiasis , encephalic amoebiasis and amebiasiscutis 3、clinical classification: （1）asymptomatic carrier （90± %） （infected with non-pathogenic strain）

29. （2） clinical manifestation ： A、 acute stage：eilema ,tenesmus ， diarrhea ， mucopurulent bloodystool like Jam,stinking smell as of rotten fish ，4-6times/day. B、chronic： abdominal distension 、 abdominal pain 、 emaciation 、 anemiaet al. 4、 Intestinal amoebiasis ： （1） primary sites ： ileocecus 、 sigmoid colon

30. （3）、 pathological characteristics ： • The primary focus are at ileocecus 、 sigmoid colon which are restricted to tunica mucosa except serious damage . Enteroscopy show: Congestive focus with a very tiny ulcer as a needle in the center

31. B. Acute case: trophozoite breaks through tunica mucosa goes into submucosa then causes liquefactive necrosisand flask-like ulcers.The trophozoites can be detected near ulcers.The mucosa is normal among ulcers—differ with the bacillary dysentery. C、 chronic case： amebic granuloma –stimulated by the chronic inflammation fibroplasia

32. （2） clinical manifestation ：Normally have intestinal amoebiasis history, hepatomegaly ， hepatodynia occasionally， radiate toward to right shoulder, progressive weight loss、 anemia 。 （3） pathological feature ： sterility 、liquefactive necrosiswith Coffee-like fester and rough walls of abscess.Lymphocytic infiltrate.The trophozoites can be detected near abscess. 5、 hepatic amebiasis ： （1）primary sites：right lobe of liver

33. hepatic amebiasis Without fester

34. pathological section of hepatic amebiasis

35. trophozoite magnified

36. drainage hepatic amebiasis Diabrotic abscess

37. 6.Other amoebiasis location——lung、brain、skinet al。 clinical manifestation ：different symptoms according the location。

38. Examination of laboratory

39. Note: when detect trophozoite,stool need:keep fresh,warm,clean, accuracy 1、 etiologicalexamination ： （1） stool examination ： A、 Physiological saline smear method ：acute bloody purulent stool ，intestinal amoebiasis liquid stools ；----first choose B、cyst concentraion method (centifugal sedimentation method) Ifrepeaded 5 times, 90% patients can be found

40. 1、 etiologicalexamination ： （1） stool examination ： 2、 immunologic test ：key experiment ELISA：suit for hepatapostema （ relevance ratioreach 95～100%）and invasive bowel disease(85～95%）。 （2） bioptic ： A、 Living tissue puncture （ Liver aspiration ）； B、 colonoscopy ：Take the samples from the edge of the ulcer （85±%amebic dysentery can be diagnosed ）。

41. case analysis Male, 54 years. Diarrhea for 2months， hematochezia 2 weeks，primary diagnosis was colon cancer。 B ultrasonicchecked：there were 2 low echo enclosed mass in right liver，diameters were7.7cmand 6.0cm respectively; the echo was nonuniform ，diagnosed rjght liver cancer”， colonoscopy show“ulcerative colitis”。Needle Biopsy guided by B ultrasonic， some liquid like coffee was aspirated out, mobile ameba trophozoite were seen through Saline smear.So it was diagnoded as.Abscesses puncture pumping was performed 3times in 2weeks，obtained fester 650ml in total，,treated with metronidazole at the same time. He was cured after 1 month.

42. Discussion： 1.What diseases were misdiagnose about this patient？Why? 2.Where is the main position of the disease？Is there any relationship with hematochezia? 3.What is the final diagnosis? How do you make a judgment? 4.How did the man infected？ What diseases should be identified ?

43. Epidemic＆prevention

44. Geographic Distribution: Worldwide, with higher incidence of amebiasis in developing countries. In industrialized countries, risk groups include male homosexuals, travelers and recent immigrants, and institutionalized populations In China, there are more infected patients in south China than in north China;more in county than city. Crowd infection ratesis1～2 % 。 Itisepidemic in tropics and Subtropics .There is high infection ratio at Mexico 、 South America 、 India 、 Tropical Africa 。

45. Epidemic （2） transmission route ： Through the mouth of interpersonal communication. Water,fingers,food or tools were comtaminated by cysts;Transmitted through fly or cockroach （3） susceptible population ：All easy to infect，especial for tourers, homoerotism, Immunocompromised Individuals, malnutrition and malignancy et al. 2、 epidemic factors： （1） With the source ：cysts carrier（most important transmission factors）、patients。

46. prevention 1、treat patients and cyst carriers （medicine： metronidazole ）。 2、control feces and protect water 3、sanitation for water ;food。 4、regularly inspect the cook。

47. Murder worms? nose 6 person died Naegleria fowleri

48. Home-used tap water USA--CDC: 100amebic keratitis 83using contact lenses • contact lenses Acanthamoeba Keratitis 在27名研究对象。

49. Many species;commonly living in water。 . Naegleria fowleri:living in fresh water with trophozoite and cyst stages. Infective ways：contact sewage or swimmingin pool.parasite invade nose then along nasal mucosa and olfactory nerve goes into brain cause 。Causing primary amebic encephalitis which is very danger and mortality is very high . Acanthamoeba ：includetrophozoite and cyst stages.living in fresh water. Infective ways： not very clear. Living in humanbrain ，cornea--- Acanthamoeba Keratitic and Granulomatous amebic encephalitis 。

50. Review: What is the Amoeba Histolytica? What kind of disease causedd by Amoeba Histolytica ,and what are their symptoms and pathogenic mechanism? How to diagnose?