Other intestinal protozoa

1. Other intestinal protozoa • Balantidium coli • Cryptosporidium parvum • Isospora belli 1

2. Balantidium coli • Primarily a zoonotic intestinal parasite: • Horses, cows, pigs • Farm workers at risk • Symptoms similar to amebiasis except, No abscesses in peripheral organs 2

3. Balantidium colimorphology Balantidium is the largest protozoan and only ciliate known to parasitize humans 3

4. Balantidium colilife cycle Contracted by consumption of material contaminated with feces of some farm animals. Cyst is the infective stage Trophozoites reside in the lumen of large intestine where they divide by transverse binary fission. Encystation is triggered by dehydration of intestinal content, it may also occur outside of the host. 4

5. Balantidium coliDiagnosis History, symptoms and finding the typical trophozoites and cysts in the stool 5

6. Balantidium coliPrevention and treatment Prevention Avoid ingestion of material contaminated with animal feces Treatment Tetracycline Iodoquinol Metronidazole 6

7. Cryptosporidium parvum Major cause of epidemic diarrhea Animal reservoir (domestic animals) Severe diarrhea and invasive infection in AIDS patients 7

8. Cryptosporidium parvum Cryptosporidium is typically a acute short term infection. The parasite is transmitted by oocysts that, once infected, excyst in the small intestine. The trophozoites (5 mm in diameter) multiply by sexual reproduction. 8

9. Cryptosporidium parvumTreatment and control • Self limiting in normal individuals • Severe and prolonged disease in AIDS patients • Nitazoxanide • Proper sanitation and clean water supply 9

10. Isospora belli Belli is a protozoan of cosmopolitan distribution occurring especially in warm region of the world. It multiplies both sexually and asexually Microscopic demonstration of the oocysts with one sporocyst. Oocysts are thin walled transparent and ovoid in shape 10

11. Isospora belli • Causes giardiasis-like but milder symptoms • Self limiting in normal individuals • Severe and prolonged disease in AIDS patients 11

12. Isospora belli • Diagnostic stage of I. Belli in fresh stool oocyst with 1 sporocysts • Treatment: TrimethoprimSulphamethoxazole 12

13. Trichomonasvaginalismorphology • Trichomoniasis: one of the most widespread sexually transmitted disease world wide • Human parasite only • World-wide • 5% in normal population • 70% among prostitutes 13

14. TrichomonasvaginalisSymptoms • Male • Rarely symptomatic • Occasionally mild urethritis and/or prostatitis 14

15. TrichomonasvaginalisSymptoms Women Often asymptomatic Mild to severe vaginitis in heavy infections Copious fowl-smelling yellow discharge Growth of the organism favored by high pH: >5.9 (N=3.5-4.5) 15

16. TrichomonasvaginalisDiagnosis Giemsa stained T. vaginalis (vaginal swab) 16

17. Trichomonasvaginalisdiagnosis Fresh vaginal swab sample examined under the microscope showing one trophozoite There is no cyst in the life cycle, transmission is via trophozoite stage 17

18. TrichomonasvaginalisDiagnosis T. vaginalis T. hominis 18

19. TrichomonasvaginalisPrevention Treatment • Prevention: • Personal hygiene • Condom use • Treatment • Metronidazole • Vinegar douche (decreases pH) 19

20. Metronidazole: Mechanism of action- Metronidazole is nitroimidazole compound Pfizer markets the drug under the trade name Flagyl Metronidazole is a prodrug. The nitro group of the compound is reduced by ferredoxin and the resulting products are responsible for disrupting the DNA helical structure which leads to inhibition of nucleic acid synthesis 20

21. Trimethoprim: Mechanism of action- Trimethoprim belongs to chemotherapeutic agents known as dihydrofolate reductase inhibitors Trimethoprim acts by interfering with the action of dihydrofolate reductase enzyme which prevents formation of tetrahydrofolic acid Tetrahydrofolic acid is required to synthesize thymidine (component of DNA). Therefore, inhibition of the enzyme prevents replication of DNA 21

22. Sulfamethoxazole: Mechanism of action- Sulfamethoxazole is a sulfonamide. It is most often used as part of a synergistic combination with trimethoprim Sulfonamides are structural analogs of para-aminobenzoic acid (PABA) They inhibit normal utilization of PABA for the synthesis of folic acid which is an important component of DNA synthesis 22

23. Mechanism of action- continued Dihydropteroate diphosphate + PABA Dihydropteroate diphosphate synthetase X sulphonamides Dihydropteroic acid Dihydrofolic acid Dihydrofolate reductase X trimethoprim Tetrahydrofolic acid 23

24. Nitazoxanide: mechanism of action Nitazoxanide: Following oral administration in humans, nitazoxanide is rapidly hydrolyzed to an active metabolite tizoxanide The anti-protozoal activity of tizoxanide is believed to be due to interference with pyruvate-ferredoxin oxidoreductase (PFOR) dependent electron transfer reaction which is essential to anaerobic energy metabolism 24

25. Intestinal & uro-genital protozoa of man: summary 25

26. organism Trans-mission symptoms diagnosis Treatment B. coli oro-fecal; zoonotic. Same as amebiasis, but no abscesses Stool: ciliated trophs and/or cysts Metronidazole Diarrhea; no mucus or blood Oocyst in stool Nitazoxanide C. parvum Oro-fecal zoonotic Oocysts in stool I. belli Oro-fecal Same as giardiasis Sulpha drugs T. vaginalis Sexual Vaginitis; occasional urethritis/prostatitis Flagellate in vaginal/ urethral smear Metronidazole Intestinal & uro-genital protozoa of man: summary Continued… 26

27. Organism Disease Epidemiology Central Africa: 10x106 T. brucei sleeping sickness T. cruzi Chagas’ disease South/Central America: 20x106 L. donovani Asia: 10x106 visceral leishmaniasis L. tropica cutaneous leishmaniasis Mediterranean: 5x106 L. Braziliensis and other mucocutaneous leishmaniasis South/Central America: 10x106 Blood and tissue protozoa of man 27

28. Organism Disease Epidemiology malaria Tropics and subtropics: 200x106 P. falciparum, P. ovale, P. vivax, P. malariae T. gondii Toxoplamosis world wide: opportunistic B. microti babesiosis, anemia North America and Europe Blood and tissue protozoa of man 28

29. Trypanosomiasis African trypanosomiasis (sleeping sickness) T. brucei, rhodesiense T. bruceigambiense American trypanosomiasis (Chagas’ disease) T. cruzi 29

30. Trypanosomegeneral morphology 30

31. African trypanosomiasisgeographic distribution of T. brucei 31

32. Trypanosoma bruceimorphological forms Epimastigote (crithidial form) in the insect Trypomastigote (trypanosomal form) in the mammalian host 32

33. Trypanosoma bruceilife cycle Tsetse fly 33

34.  Stage Organ Involved Symptoms Bite reaction Skin Non pustular (bumps without pus), itchy, painful chancre; no scar Parasitemia Blood circulation and lymph nodes Malaise, lassitude, insomnia, fever, edema, lymphadenopathy CNS (T. gambiense) Heart (T. rhodesiense) Personality changes, shuffling gait, lack of interest, tremulous speech, mental retardation, sleepiness, cardiac failure. CNS stage Symptoms of African trypanosomiasis 34

35. T. Brucei :Winterbottom’s sign 35

36. T. Brucei : coma 36

37. T. Brucei : pathology and Immunology Immunology • Antibodies are not protective due to antigenic change • Polyclonal B cell expansion; Hyper-IgM • hypocomplementemia • Immunosuppression Pathology • Inflammation • Antigenic change • CNS damage by the organisms 37

38. T. Brucei : antigenic variation 38

39. T. Brucei :diagnosis • History of travel and fly-bite • Symptoms • Blood smear and/or CSF • Anionic support concentration • Bioassay (mouse) • IF 39

40. T. Brucei :Prevention and treatment Prevention Treatment • No effective vaccine (changing VSG) • Tsetse fly control • Insect-bite avoidance • Suramin or pentamidine • Acute disease • Suramin • Pentamidine • Chronic (CNS) disease • Melarsoprol (arsenic) 40