1. الدكتورة زينب خالد خليل
ماجستير احياء مجهرية
MEDICAL PARASITOLOGY .
الدكتورة زينب خالد خليل

2. Introduction To Parasitology.
د. زينب خالد خليل Lec. 1
Introduction To Parasitology

3. Parasitology
Is a science, study the relationship between two organisms one called parasite & the other is called the host .

4. CLASSIFICATION OF PARASITES:
Parasitic kingdom include three phyla
1- Protozoa.
2- Helminths.
3- Arthropods.

5. 1- Class sarcodina: Parasites that move by means of
I- Protozoa :
Is a phylum of the animal kingdom consisting of unicellular parasites, divided into 4 classes according to the organ of locomotion:
1- Class sarcodina: Parasites that move by means of
pseudopodia example Entamoeba histolytica.
2-Class mastigophora : Parasites that move by
means of flagella example Giardia lamblia

6. 3- Class ciliates : parasites that move by means of cilia example Balantidium coli .
4- Class Sporozoa : parasites have both sexual and asexual reproductive organs, all these parasites are intracellular and they have no organ of locomotion example Plasmodium parasites causing malaria.

7. II- Helminths :
They are metazoa ( Multicellular parasite ) wormlike parasite, divided into 3 classes :
1.Class Nematoda ( Roundworms ) :
a- Intestinal nematodes, e.g, Ascaris lumbricoides .
b- Tissue nematodes, e.g, Wuchereria bancrofti .

8. 2- Class Cestoda ( Tapeworms) :
They are flattened and segmented worms, e.g: Taenia saginata .
3- Class Trematoda (Flukes):
They are flattened leaf- shaped worms. e.g: Schistosoma heamatobium.

9. III- Arthropods :
These parasites having exoskeleton and jointed legs, divided into 2 classes:
1- Class Insecta :e.g. Mosquitoes, lice and fleas .
2- Class Arachnida :e.g. Ticks and mites .

10. GENERAL TERMINOLOGY:
* pathogenic parasite (parasitism): A parasite infect the host and cause tissue changes or a disease (harmful parasite).
* Commensal parasite (Commensalism): The association of two different species of organisms in which one of them is benefited and the other neither benefited nor injured .

11. * Ectoparasite: A parasite present on or in the exterior surface of a host.
* Endoparasite: A parasite present within the body of its host .

12. Facultative parasite: A parasite capable of living an independent or a parasitic existence .
Obligatory parasite: A parasite is capable of living as parasitic on a host, but it can not exist as independent living.

13. Types of hosts
*Definitive host: The animal or human in which a parasite passes its adult stage and/ or the sexual reproductive phase can take place.
*Reservoir host:
An animal e.g. (dogs,cats or rodents) which carry a species of parasite from which man become infected. The host do not get the disease or its carried as a subclinical infection.

14. * Carrier. A host carring a parasite but not showing any clinical sings or symptoms.
* Accidental ( or incidental ) host : Infection of a host other than the normal host species.

15. Vector:
Any arthropod or other living carrier which transport a pathogenic micro-organism from an infected to a non infected host. A vector may transmit disease :
(1)passively called (mechanical vector) e.g.housefly
(2) The vector is essential in the life cycle of the pathogenic parasites called (biologic vector) e.g.mosqutoes.

16. Ectoplasm: The gelatinous material beneath the cell membrane .
*Endoplasm: The fluid & inner material of a protozoal parasite .

17. *Flagellum(flagella) :
An extension of ectoplasim which provides locomotion similar to a tail .

18. Pseudopod:A protoplasmic extension on the trophozoites of amoeba allowing them to move and engulf food .
Cilia: Hairlike processes attached to a free surface of a cell; function for motility of fluids at the surface of the cell, e.g. Balantidium coli .

19. د. زينب خالد خليل Lec.(2)
Amoebas 19

20. Amoebas:
The genus Entamoeba include many amoebas that infect humans, but not all of them are associated with disease,like E. histolytica which is a pathogenic amoeba causing intestinal and extraintestinal Infections.

21. None pathogenic amoeba :
These parasites are commensal none pathogenic but they are important because they may be confused with E.
histolytica in diagnostic investigations. These amoebas include many free-living and parasitic amoebas.
The most amoebas affecting human being are:

22. 1- E.coli.
2- E.gingivalis .
3- Dientamoeba fraglis Endolimax nana .
5- Iodoamoeba butschlii .
6- Other amoebas infecting human are morphologically very simillar to E.histolytica, e.g, E.hartmanni and E.dispar.

23. 7- Free living amoebas are Negleria & Acanthamoeba are accidental parasites of human being .The majority of these amoeba are non-pathogenic commensal parasites or only cause mild infection.

24. ENTAMOEBA HISTOLYTICA24

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

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

28. 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 .

29. 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.

30. Life cycle of E. histolytica:

31. Epidemiology : .
* The incidence of Amebiasis is common & high in tropical & subtropical areas especially in areas of lower socioeconomic status due to:
poor sanitation(2) overcrowding & (3)malnutrition
It is estimated that up to 10% of the world`s population may infected with E.histolytica.

32. Transmision of amoebiasis occure through:
1. Mature cyst is the main sourse of the infection which passing with the feces of chronic patients or asymptomatic carrier .
2. Human being acquire the infection via contamination of food, drinks, vegetables or hands with infective cysts especially in restorants .
3. Flies (House fly) play an important roles in trasmission of these cysts to the food of human .

33. Pathogenesis of E.histolytica:
The Pathogenic activity of E. histolytica depend upon :

34. 1- The resistant of the host .
2- The number of the amebas.
3- Presence of pathogenic bacteria.
4.Presence of physical & chemical injury of the mucosa .

35. The lesions produced by E. histolytica are
primarily in large intestine and
seconderily extraintestinal especially the liver, brain or any organ of the body may be affected .

36. Pathogenisis of Intestinal lesion :
1.The lesion vary from small ulcer to a large typical flask shape ulcer.
2.The ulcer has a wide base and narrow opening with irregular elevated edges .
3.The ulcer charecterized with large area of tissue necrosis, cell infiltration & rapid lysis of inflamatory cells.
4.The amoebas usually found on the floor of the base of ulcer.

37. E. histolytica in the large intestine
( Flask shape ulser )

38. 1- The incubation period range from 2 – 4 weeks .
Clinical features of intestinal lesion :
1- The incubation period range from 2 – weeks .
2- The majority of infections with E.histolytica show no symptoms or show symptoms which varies from mild to intense and long lasting .

39. The typical symptoms include :
1- Diarrohea, The diarrohea frequently alternates with constipation or soft stools may contain mucous but no visible blood .
2-Abdominal cramps.
3-Nausia.
4-Anoroxia.

40. 5- Dysentery :
Which is usually starts slowly with abdominal cramps and associated with loose stool and diarrhea with blood , mucus and necrotic tissues.
6- Few patients especially children may show fever, vomiting, abdominal tenderness .

41. The complications of intestinal amoebiasis:
1- Appendicitis .
2- Intestinal perforation .
3- Hemorrhage .
4- Liver abscess.
5- Ameboma (Granulomas).

42. Extraintestinal Amoebiasis :
1.The metastasis of amoeba usually via blood streem or by direct extension after intestinal perforation to the peritonium. The amoeba may cause local abcsess or peritonitis or migrate to the liver which is the most commonly affected than other organs e.g, lungs, perianal skin or brain.

43. Extraintestinal Amebiasis

44. 2.Amoebic liver abscesses: Are the most common extraintestinal amebiasis and characterised By:
a.Hepatomegaly, Liver tenderness, fever and anorexia .
b. Liver function tests are usually normal or slightly abnormal .
c. Liver abscesses will occasionally rupture into the peritoneum causing peritonits

45. 3.Pulmonery amoebiasis :
a.The clinical symptoms are: cough, chest pain, dysnea and fever .
b.The sputum may be purulent or contain blood and trophozoites of E. histolytica.

46. 4. Cutaneous amoebiasis :
It is caused by contact of the skin with amoebic abscess which lead to fistula formation in the skin.

47. Diagnosis of Amoebiasis :
1- Stool of patient should be examined microscopically :
a- The typical amoebic stool is contain blood, mucous , WBC & Bacteria .
b-Direct method with saline for motile trophozoite .
C-Stool specimens should be stained usually with ioden and microscopically examined for cysts of E.histolytica .

48. 2- Culture of stool.
3- Sigmoidoscopy may reveal the charecteristic flask-shaped ulcers especially in sever cases .

49. 4- Biopsy & fluid from large intestine aspirates also be examined microscopically for trophozoites .
5- Serology, is very important for the diagnosis of extraintestinal amoebiasis
e.g: Indirect haemagglutination (IHA) & Polymirase Chain Reaction (PCR test) .

50. 6- Ultrasound, CTscan, MRI can be used to detect hepatic abscesses .

51. Treatment :
1. A symptomatic (source of infection) patients can be treated with Diiodohydroxyquine with tetracycline.

52. Treatment Cont… :
2. Symptomatic patients with diarrhoea or dysentary or extraintesinal amebiasis should be treated as follows :
a- Supportive methods
Patients should remain in bed and receive a high protein and high vitamin with adequate fluids .

53. b. Chemotherapy for sever amoebiasis:
1.Metronidazol (Flagel) is the drug of choice :
750 mg three times a day, orally for 5 – 10 days.
2.Tetracycline & diiodohydroxyquine are recommended to be given to the patient since metronidzol may not always cure the intestinal infection .

54. Prevention & Control :
1- All human infections should be treated
2- A symptomatic carriers should be treated especially those working in restorants .

55. 3- Effective enviromental sanitation is necessary to prevent water ,food , and vegitable contamination, e.g. Sewage disposal should be treated with chemical before used as fertiliser in gardens.
4- Chlorination & filtered water supply are important to kill the cyst of E.histolytica.

56. 5- Insects should be controlled by insecticides.
6- Uncooked vegetables should be washed with running water. .

57. Lec.(3) د. زينب خالد خليل
Balantidium coli

58. Balantidium coli *Primarily a zoonotic intestinal parasite:
animals that represent a source of infection include Horses, cows, pigs
*The most risky people are farm workers
*Symptoms similar to amoebiasis except, No extraintestinal infection

59. Morphology Balantidium is the largest protozoan and only ciliate
known to parasitize humans

60. Trophozoite morphology
mic
Cilliated parasite
Oval shape
Greenish yellow color
Kidney or bean shape Macronucleus
Small micronucleus
Retractile food vacule

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

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

65. Life cycle

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

67. Clinical signs and symptomes
Intermitent periods of diarrhea and constipation
Bloody diarrhea
Abdominal pain
Anorexia
Ulceration of large intestine
Tender colon
Cachexia
Gangrenous lesions could occur

68. Diagnosis 1.History: if there any animal contact. 2.Symptoms
Clinical signs could confused by E. histolytica infection
3. Laboratory tests: finding the typical trophozoites and cysts in the stool

69. Diagnosis cont…..
Laboratory methods to detect (cyst or trophozoite) in stool by
Direct wet mount preparation methode
Stained smear by iodin
Looking for characteristic kidney shape nucleos and retractile food vacule

70. Prevention & control
Avoid ingestion of food and drinks contaminated .by animal feces

71. Treatment
1.Tetracycline
2.Iodoquinol
3.Metronidazole

72. Thank you