Theme: Medical and biological basics of parasitism. Medical protozoology. Medical helmintology

1. Theme: Medical and biological basics of parasitism. Medical protozoology.Medical helmintology Lecturer: ass. prof. Tetyana Bihunyak

2. The questions: 1. The forms of association between organisms of different specieses. 2. Classification of parasites and hosts. 3. Protozoa – human parasites. 4. Helmintoses.

3. Symbiosis is the living together or close association of two dissimilar organisms. • Commensalism is symbiosis in which one party (commensal) is benefited and the other party (host) receives neither benefit nor harm. • Parasitism [Gr.parasitios eating with another] is symbiosis in which one party (parasite) benefits at the expense of the other (host). • Parasitology [Gr. Parasitos parasite-logy] is the science of parasitism and parasites. • Medical Parasitology is the science or study of parasites of humans. Medical Parasitology consists of: • Medical Protozoologyis the study of human parasites of Protozoa. • Medical Helminthologyis the study of human parasitic worms of Trematoda, Cestoda, Nematoda. • MedicalArachnoentomologyis the study of parasites of Arthropoda.

4. Parasite lives upon or within another living organism (host) at whose expense it obtains some advantage. • External parasite(ectoparasite) lives on skin or hair of host. • Internal parasite(endoparasite) lives in body organs, body tissues, body cells, body cavities of host. • Host is an organism that harbours or nourishes another organism (parasite). • Definitive host (final h.) is a host that harbours the adult or sexually mature parasite. • Intermediate host thatharbours the immature or asexual stages of the parasite. • Reservoir host an animal that harbours the same species of parasites as man and constitute a source of infection to him. • Vector is an arthropod that carriers a parasite to its host.

5. Invasive diseases are caused by animals. • Protozoan diseasesare caused by Protozoa. • Anthroponotic diseases are characteristic for humans. • Anthropozoonoticdiseases are characteristic for humans and animals. • The ways of agent transmission of invasive diseases: • contagion (by skin contact, sexual contact); • alimentary or faecal-oral transmission (ingestion of raw or undercooked food or use of drinking water containing the infective stage of the parasite); • by blood (by bite of vector containing the infective stage, blood transfusion); • congenital (through the placenta)

6. Morphology and Ultrastructure of Protozoa 1) Protozoa are unicellularanimal organisms. 2) Each protozoon performs all functions of life. 3) Sizes is from 1 micro;m until 150 micro;m. 4) The protozoa have cytoplasm and nucleus. 5) The cytoplasm is differentiated into ectoplasm (the outer layer) and endoplasm(the inner layer). 6) The ectoplasmfunctions are: protection, locomotion, ingestion of food, excretion and respiration. 7) Locomotion either by pseudopodia, cilia andflagella. 8) The endoplasm encloses: organelles, contractive vacuoles for osmoregulation, food vacuoles containing food during digestion. 9) The nutrition of all protozoa is holozoic. Absorption of liquid food through the body surface, or ingestion of solid particles by the help of pseudopodia or through the cytostome. 10) Reproduction may be asexual or sexual.

7. Kingdom Animalia • Subkingdom Protozoa • Phylum 1. Sarcomastigophora • SubphylumSarcodina.ClassLobozea. Specieses: Entamoeba histolytica, E. coli, E. gingivalis. • Subphylum Mastigophora (or Flagellates). • ClassZoomastigophorea.Specieses: Trypanosoma brucei gambriense, T. b.rhodesiense, T. cruzi, Leishmania donovani, L. tropica, Lamblia intestinalis, Trichomonas vaginalis, T. hominis. • Phylum 2.Apicomplexa. Class Sporozoa.Specieses: Plasmodium vivax, P. malariae, • P. falciparum, P. ovale, Toxoplasma gondii. • Phylum 3. Ciliophora. Class Ciliata.Species: Balantidium coli.

8. Class Lobozea: 1)  Motion is by pseudopodia. 2)  Reproduction is by binary fission. 3)  The production of a cyst is one of the stages in the life cycle. 4) The pathogenic species for man is Entamoeba histolytica, the non-pathogenic (commensal) species are E. gingivalis, E. coli. Parasite: Entamoeba histolytica Disease: Amoebiasis, or amoebic disentery Morphology: 1) forma magna; 2) forma minuta; 3) cyst.

9. Entamoeba histolytica trophozoite forma minuta Entamoeba histolytica mature cyst Amebiasis

10. Life cycle of Entamoeba histolytica Host: Homo sapiens Transmission:faecal-oral (alimentary) Infective stage: mature cyst Localisation:large intestine Pathogenicity: 1) Intestinal amoebiasis: formation of ulcers of the wall of the intestine, acute or chronic diarrhoea, stool containing blood and mucus; may be asymptomatic infection. 2) Extra- intestinal amoebiasis: abscess of liver, lungs, brain, skin.

11. Amebic Colitis:Severe dysentery with multiple ulcers in the large bowel, and a bloody diarrhea

12. Entamoeba histolytica trophozoites in section of intestine (H&E) 

13. Gross pathology of liver containing amebic abscess 

14. Amebic liver abscesses

15. Amoebiasis Laboratory diagnosis: Fresh stools are examined under the microscope. E. histolytica (forma magna and cysts with 4 nuclei) can be demonstrated in the stools. Prevention: Treatment of patients and asymptomatic cyst carriers; protection of foodstuffs and water from flies and contamination with faeces; the staff of catering establishments must be examined for cysts carriage; health education of the population.

16. Class Sporozoa: 1) lack locomotory organelles; 2) complex life cycles (sexual and asexual phases); 3) alternation of hosts; 4) the pathogenic species for man are: Plasmodium vivax, P. malariae, P. falciparum, P. ovale, Toxoplasma gondii. MALARIA PARASITES OF MAN

17. Geographical distribution of malaria:in parts of Africa, Asia, Turkey, the West Indies, Central and South America, and Oceania

19. LIFE CYCLE OF THE MALARIA PARASITE Exoerythrocytic schizogony (liver phase) 1.  Mosquito bites man, takes blood meal and injects sporozoites from its salivary gland into the blood. 2.  Sporozoites travel through blood to the liver, multiply asexually to form merozoites, which upon liver cell rupture, are released into the bloodstream and infect erythrocytes. Erythrocytic schizogony (blood phase) 1.  Merozoites enter the erythrocytes, forming a ring-like trophozoite; mature trophozoites asexually divide to form schizonts. 2.  Schizont develops into merozoite daughter cells, then lyses the erythrocytes membrane, leading to periodic paroxysms of disease due to resultant parasitemia. P. ovale, P. vivax, P. falciparum — membrane lysis in 48 hours, P. malariae —membrane lysis in 72 hours. 3.  Some merozoites develop into macrogametocyte and microgametocyte. Sporogony 1.  Mosquito ingests gametocytes with blood meal. 2.  Gametocytes enter mosquito gut. 3.  Zygote, formed from fertilization, invades gut wall to form an oocyst within 24 hours following ingestion 4.Sporozoites are formed, released into the stomach, migrate to salivary glands, then injected into human with blood meal.

20. MALARIA PARASITES OF MAN Intermediate host:Homo sapiens Definitive host:Anopheles mosquito Transmission:by bite of female Anopheles mosquito Infective stage for man: sporozoite Infective stage for mosquito: gametocyte Localisation: liver, blood Prevention: chemoprophylaxis and personal protective measures against the mosquito vector (Anopheles).

21. Blood stages of Plasmodium: 1) young trophozoites (ring forms); 2) growing trophozoites; 3) mature trophozoites; 4) mature shizonts; 5)macrogametocytes; 6) microgametocytes

22. Patient with malaria. Clinical manifestations: fever, anemia, splenomegaly, hepatomegaly

23. Laboratory diagnosis of malaria: Microscopy of thin and thick films blood smears. Different stages of the parasite (trophozoites, schizonts, and gametocytes) can be demonstrated in the blood.

24. Parasite:Toxoplasma gondii Disease:toxoplasmosis Intermediate hosts:birds and mammals, including humans Definitive hosts: cats Localisation: brain, eyes, skeletal and cardiac muscles, liver, and lungs Transmitted to humans by: 1) ingestion of undercooked infected meat (cysts and pseudocysts); 2) contamination of food or drink with infected cat faeces (oocyts); 3) transplacental (congenital)

25. Toxoplasma gondii1) pseudocysts; 2) trophozoites; 3) cysts; 4) oocysts

27. Toxoplasma gondii in human liver

28. heart lung

29. Congenital toxoplasmosis Clinical manifestations. Hydrocephalus, lesions in the organs of the vision (chorioretinitis), cirrosis of the liver and enlargement of the spleen.

30. Prevention of toxoplasmosis: washing of hands before meals and after handling animals and animal products, and the prohibition of preparing food from insufficiently cooked meat products, in particular liver. All women with a history of spontaneous abortion must be examined by laboratory methods for prevention of congenital toxoplasmosis

31. Class Zoomastigophorea: • Motion is by flagella. • Reproduction is by longitudinal binary fission. • 3) Complex life cycles include alternation of hosts. • Parasitical species of tissues and blood: • a) Trypanosoma • b) Leishmania • Their transmission requires a biological vector. • Species living in the digestive tract and genitals: • a) Lamblia intestinalis • b) Trichomonas vaginalis • c) Trichomonas hominis • Their transmission does not require a biological vector.

32. Parasites: Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense Disease: African trypanosomiasis, or sleeping sickness Geographical distribution: West and Central Africa Transmission:by bite of infected tsetse flies (Glossina palpalis) Reservoir hosts of T.b.gambiense are:man, domestic pig, cattle, dog, antelope. Reservoir hosts of T.b.rhodesiense are:antelope, lion, hyena. Localisation: blood, lymph nodes, cerebrospinal fluid, brain, muscles.

33. Morphology of trypanosoma: spindle-shaped cells with an undulatory membrane and pointed flagella at the end. The organisms are motile, 25-40 micro;m in length.

34. Scanning electron micrograph (5.500 × magnification) of Trypanosoma brucei gambiense among red blood cells

35. Tsetse fly (Glossina palpalis) is a vector of Trypanosoma brucei

36. Pathogenicity: • From the site of bite trypanosomes reach the blood and lymphatics where they multiply. • 2) There is perivascular infiltration with chronic inflammation, leading to meningoencephalitis. • 3) The patient suffers from fever, rash, headache, lymphadenopathy, oedema of the brain. There are alternating periods of fever and apparent recovery. This is followed by depression and progressive lethargy. • 4) Rhodesien form develops within weeks to months, Gambian form develops within years. The disease becomes chronic and persists for months and even years.

37. Parasite: Trypanosoma cruzi Disease: American trypanosomiasis, or Chagas’ disease Geographical distribution: South and Central America Transmission:1) by bite of infected bug species of the family Triatomidae ; 2) congenital; 3) by blood transfusion. Reservoir hosts:armadillos, opossums, rodents, monkeys, dogs, cats. Localisation: blood (in acute phase), cells of lymph nodes, spleen, liver, brain, muscles.

38. Trypanosoma cruzi was discovered in 1909 by C. Chagas in Brazil

39. Bug of family Triatomidae is vector of Trypanosoma cruzi

40. T. cruzi cardiac muscle

41. Clinical manifestation: fever, oedema of the face, and enlargement of the thyroid glands, lymph nodes, spleen, and liver, heart alterations

42. Parasite: Leishmania tropica Disease: Cutaneus leishmaniasis Geographical distribution: Asia, Africa, Europe Transmission:by sand flyvector - Phlebotomus sergenti (in Iran, Iraq, and India); Phlebotomus papatasi (in southern France, Italy, and certain Mediterranean islands) Hosts:man, dogs, wild rodents Localisation: cellsofskin

43. Morphology of leishmania • Intracellularamastigotes(without flagellum) 2 - 6 micro;m; live in man • Promastigotes (with flagellum) develop in the intestine of the sand fly

44. Phlebotomus sandfly is vector of Leishmania tropica

45. Clinical manifestation:development of a cutaneous papule that evolves into a nodule, breaks down to form an indolent ulcer, and heals, leaving a depressed scar. Laboratory diagnosis:detection of the Leishmania parasites in cells of skin. Prevention:early diagnosis, extermination of sandflies and dogs and rodents infected with leishmaniasis, and vaccination.

47. Parasite: Lamblia intestinalis Disease: lambliosis Geographical distribution: cosmopolitan Host:man Transmission:faecal-oral (alimentary) Infective stage: cyst Localisation: the small intestine (duodenum) and gall-bladder

48. Life cycle of Lamblia intestinalis

49. Lamblia intestinalis Morphology:Trophozoites are symmetrical, pear-shaped organisms with two nuclei. The body is 10 - 18 micro;m with four pairs of flagella. Cysts are oval-shaped which are 10 - 14 micro;m and have four nuclei.

50. Scanning electron micrograph (5.500 × magnification) of Lamblia intestinalis in duodenum