1. Introduction to Protozoa

2. General Account Unicellular animal with full functions
Distribute widely: water,soil, etc.
Total species 65,000
Free-living: majority
Parasitic: about 10,000

3. Medical Protozoa Pathogenic protozoa Opportunistic parasite(机会致病)
Not normally pathogens
Become pathogenic due to impairment of host resistance
Clinical importance of the AIDS epidemic

4. Basic Structures Plasma membrane:侵袭致病,免疫反应 Cytoplasm Nuclear
Ectoplasm: locomotion , ingestion, etc
Endoplasm: metabolism
Nuclear
Vesicular form(泡状核) or compact form
Locomotive organelle
Pseudopodium(伪足), flagellum(鞭毛), cilia(纤毛)

5. Mode of Reproduction Sexual reproduction Asexual reproduction
Binary fission(二分裂法): results in 2 daughter cells
Schizogony(裂体增殖): multiple fission, results in multiple cells
Endodyogony(内二芽增殖): by internal budding results in 2 cells
Sexual reproduction
Conjugation(接合生殖): exchange of nuclear materials of 2
Gametogony(配子生殖) : sexually differentiated cells unit  zygote

6. Life Cycle Patterns One stage form(简单型) Two-stage form (简单型)
Trophozoite ( take food, be mobile, multiply)
Two-stage form (简单型)
Trophozoite & cyst (not mobile, with cyst wall)
Two-host form
Mammals – mammals(循环传播型)
Mammals - insect vectors(昆虫传播型)

7. Characteristics of Protozoan in Infection
Proliferation-parasitemia
No larva and adult differentiation but stage differences
May be intracellular lodgment
Opportunistic & accidental infections (free-living)

8. Medical Important Species
Amebae
Flagellates
Sporozoites
Ciliates

9. Pathogenic Intestinal Amoeba
Entamoeba histolytica

10. Morphology Trophozoite Size: 10-40 m Shape: ovoid with pseudopodium
Basic structure: cytoplasm, vesicular nucleus (chromatin granules, nuclear membrane, karyosome)

16. Cyst Size: 10-20 m Structure: cyst wall, 1-4 nuclei, chromatoid body
Physiological function:
The stage of discharge
Resistant to external surroundings
The infective stage

20. Main Points of Life Cycle
Cycle: cyst—trophozoite—cyst
Host: human being
Lodgment: large intestine
Infective stage: 4 nuclei cyst
Infective route: mouth

21. Pathogenesis Pathogenic factor Virulence Species: Immunity of host
E.histolytica (pathogenic species)
E.dispar (non-pathogenic species)
Immunity of host
Bacteria flora

22. Mechanism: contact lysis Pathology: flask-like ulcer
Clinical manifestation
Non symptomatic carriers
Intestinal amebiasis: dysentery, colitis
Extraintestinal amebiasis: liver abscess

25. Diagnosis Etiological diagnosis:
Stool examination of cyst or trophozoite
Sigmoidoscopy or aspiration
Immunological diagnosis

26. Epidemiology Cosmopolitan: 110 population
China: 3%~10%; Rural area>urban
Source of infection: carriers
Transmit route: water contamination
Insects: fly, cockroaches

27. Prevention and Control
Patients and carriers:
Intestinal amoebiasis —metronidazole
Extra~ amoebiasis —diloxanide
Water & nightsoil control
Insect vector control
Personal hygienic health education

28. Plasmodium

29. Introduction Most important tropical disease
300 million cases with one million deaths world wide in 1999;
30 million cases before liberation and cases reported with 39 death in 2000 in china;

30. 4 species infecting human
Plasmodium falciparum(恶性疟原虫)
Plasmodium vivax(间日疟原虫)
Plasmodium malariae(三日疟原虫)
Plasmodium ovale(卵形疟原虫)

31. Life Cycle & Morphology
Cycle in human (intermediate host)
Exoerythrocytic stage(红细胞外期)
Erythrocytic stage(细胞内期)

33. 红细胞外期(肝细胞内增殖) Exo-erythrocytic cycle
（速发型）
子孢子 红外裂殖体 裂殖子
sporozoite E-E Schizont Merozoite
（迟发型P.v.）
进入红细胞
P.v. 8d; P.f. 6d; P.m. 12d

34. 红细胞内期(RBC内增殖) Erythrocytic cycle
发育：环形滋养体 大滋养体
(Ring form) (Trophozoite)
增殖：早期裂殖体(Immature schizont)
RBC内发育
成熟裂殖体(子) 配子体形成
(Mature schizont) M吞噬

35. 来源 http://www.cdfound.to.it/html/pla1.htm
P.vivax: species identification is possible on the basis of the appearance of parasites of each of the four malaria species. Shape and size of asexual parasites and of macro- and microgametocytes, developmental stages in peripheral blood, modifications of infected erythrocytes, presence of dots or clefts on the red blood cells are the main differential characteristics. 来源

36. Scanning electron micrograph of Plasmodium-infected red blood cells
Scanning electron micrograph of Plasmodium-infected red blood cells. One cell has burst open, releasing merozoites

37. P.v P.f P.m P.o

38. 红内期周期 成熟裂殖体内裂殖子数和形态 P.v. 12-24个，不规则 P.f. 8-36个，不规则 P.m. 6-12个，菊花状
P.v. 48h
P.f h
P.m. 72h
成熟裂殖体内裂殖子数和形态
P.v 个，不规则
P.f 个，不规则
P.m 个，菊花状

39. 配子体形成 (Gametocyte form)
红内期裂殖子 雌雄配子体
P.v. 2-3d
P.f. 7-10d
<12个/mm3不能传播

40. 被寄生RBC的变化
P.v. 胀大 薛氏小点
P.f. 正常 茂氏点
P.m. 正常 西门氏点

41. 疟原虫对RBC的选择
P.v. 幼稚红细胞
P.f. 各种红细胞
P.m. 衰老红细胞

42. Cycle in female anopheline mosquito (definitive host)

44. 蚊体内发育(有性) Grouth in the mosequito
雌配子体
Gametocyte 雌雄配子 受精
雄配子体 (Gametogony)
动合子Ookinete 合子
Zygote
卵囊Oocyst（内含子孢子Sporozoite）

45. 疟原虫发育过程 Sporozoite Schizont 子 Ring form Trophozoite
Oocyst 吞噬 merozoite Schiont
Ookinete Zygote Gamete Gametocyte(female/male)
(动合子) (合子) (配子) (配子体)

47. Infective form: Sporozoite Period of one erythrocytic stage:
P.V 48h; P.M 72h; P.F h
Resting stage of sporozoite of P.V & P.O:
Hypnozoite (brady sporozoite) in liver cell

48. Morphology

49. P.v P.f P.m P.o

50. Pathogenesis Primary attack
Infected erythrocyte rupture  products of schizont, stimulate the release of cytokines (TNF)  paroxysm (shiver, fever, sweat)

51. Scanning electron micrograph of Plasmodium-infected red blood cells
Scanning electron micrograph of Plasmodium-infected red blood cells. One cell has burst open, releasing merozoites

52. Relapse:
It is a recurrence that taken place after complete initial clearing of the erythrocytic infection and implies reinvation of the blood stream by merozoites from activated hypnozoites in liver.

53. Recrudescence
It is a recurrence of symptoms in a patient whose blood stream infection has previously been at such a low level as not to be clinically demonstrable or cause symptoms.

54. Complications Anemia Splenomegaly: Malarious nephrosis
Hemolysis of infected erythrocytes
Hypersplenism
Autoimmunization of uninfected erythrocytes
TNF-
Splenomegaly:
Malarious nephrosis
Cerebral malaria

55. Erythrocyte, parasitized by Plasmodium falciparum, showing surface knobs.

56. Diagnosis Parasitological diagnosis: Parasite; Species; Density
Thin blood films (species identification)
Thick blood films

57. 2. Immuno-diagnosis Specific antibody detection  past malaria
Antigen detection
Specific DNA or RNA detection

58. Immunity Congenital immunity Premunition
Duffy-negative erythrocytes are resistant to P.v in West Africans
Premunition
The protective immunity persists while the malaria parasites are still in the host.

59. Possible mechanism of evasion
Evasion of immunity: An ability of malaria parasite to evade host immunity.
Possible mechanism of evasion
1) Antigenic variation
2) Sequestration (avoiding exposure to immune effector mechanisms)
3) Poor immunogenicity of its antigens (analogy exists between parasitic antigens and host molecules)

60. Treatment 1. Classes of antimalarial drugs
1) Blood schizonticides (quinine; chloroquine; artemisinin; mefloquine; sulfadoxin-pyrimethamine)
Effect on erythrocytic stage, use for acute attack

61. Purines and Pyrimidines
P-aminobenoic acid
(PABA) +
dihydropteridine
inhibition
ANTI FOLIC ACID
Sulfone
sulfanilamide
Dihydrofolate
(folic acid)
inhibition
ANTI FOLINIC ACID
diguanides
diaminopyrimidines
Tetrahydrofolic acid
(folinic acid)
Purines and Pyrimidines
Nucleinic acid

62. 2) Tissue schizonticides (Primaquine)
Effect on the stages in liver (including hypnozoite), use for prevent relapse (radical cure) of P.v or P.o malaria

63. 2. Choice of drugs
1) Treatment of vivax, malariae, ovale and chloroquine-sensitive falciparum malaria: chloroquine
2) Radical cure of vivax or ovale malaria: chloroquine + primaquine
3) Treatment of chloriquine-resistant falciparum malaria: artemisinin or mefloquine or quinine

64. Transmission and Prevention
1. Factors of transmission
1) Infected human (gametocyte-bearing)
2) Suitable species of anopheles (60 species are considered to be vectors of malaria, major vectors in China: A. sinensis, A. minimus)

65. 3) Resistance of Anopheles to insecticides of resistance plasmodium to antimalarial drugs.
4) Susceptible population
5) Other transmission mode: by transfusion, syringe, congenital transmission

66. 2. Prevention: breaking the human-mosquito-human cycle
1) Control of the source of infection by chemotherapy
2) Control of transmission route:
residual insecticides, avoidance of infected mosquitoes (bed nets impregnated with permethrin; mosquito repellents (diethyl-metatoluamide)

67. 2) Chemoproplylaxis taking suppressive drugs, beginning one week before travel to endemic area and continuing until 6 weeks after return
3) Malaria vaccines

68. Phylum sarcomastigophora Class zoomastigophorea
Flagellate
Phylum sarcomastigophora
Class zoomastigophorea

69. Leishmania donovani
杜氏利什曼原虫

70. General Introduction Zoonotic parasite
One of the 5 major parasitic diseases
Endemic northern to Yangtse river
0.5 million patients before 1949
Basically eradicated in 1958

71. Visceral leishmaniasis has a wide geographic distribution.

72. Morphology Amastigote (leishman-donovan body):
Human phase, reside in macrophage
Very, very minute elliptical body
No free flagellum
Nucleus: deep red, located at one side
Cytoplasm: blue (after right stain)
Kinetoplast: basal body; rhizoplast

74. Leishmania amastigotes, bone marrow aspirate, Giemsa stain

75. Promastigote: Vector phase Reside in the gut of sandfly
Spindle shaped with 1 free flagellum
Nucleus; cytoplasm; kinetoplast; basal body; rhizoplast
Chrysanthemum-like in culture medium

77. 来源 http://www.cdfound.to.it/html/lei1.htm

78. Main Points of Life Cycle
Host: man and sandfly
No sexual development in the host
Residing site: macrophage
Infective stage: promastigote
Infective route: inoculation of sandfly
Reservoir host: dog
Infection could also via transfusion

79. Clinical Feature Irregular, long term fever
Skin pigmentation—Kala-azar (india)
Very poor prognosis: die within 1-2 year without treatment
Reason: lack of immunity after infection;
But may gain sterilizing immunity after effectively cured

80. Clinical Manifestation
Hepatosplenomegaly
Pancytopenia (hypersplenofunction, immune lysis)
Epistaxis (nosebleed)
Nephrosis: albuminuria, hematuria
Skin lesion: PKDL
Enlargement of lymphaden

82. Cutaneous leishmaniasis of the face

83. Laboratory Diagnosis Etiological diagnosis Puncture smear Skin biopsy
Bone marrow: safe, of first choice
Lymphaden: treatment evaluation
Skin biopsy
Tissue cultivation
Animal inoculation
Probe test: DNA or McAb

84. Epidemiology Cosmopolitan: Asia, Africa, Latin, America
Distribution in China—3 types of areas

85. Plain type Hilly type Desert type Shangdon, dom. P.sinensis
Qinghai, wild P.sinensis
Desert type
Xinjiang, wild P.sinensis

86. The infection is transmitted by various species of Phlebotomus, the sand fly.

87. Epidemic Links Source of infectin: patients and dogs
Route of infection: phlebotomus spp.
Susceptible population: all human beings ( but potent immunity developed after cure)

88. Control Treatment of patients: Sodium stibogluconate
Kill infected dogs
Eradicate sandfly: weak points
Limited flying capacity
Long breeding course
Short seasonal prevalence
Sensitive to insecticide

89. Reasons for a Successful Control in China
Free charge of treatment
Potent immunity after being cured
Large production effective drug
Weak points of sandfly

90. Giardia lambia
蓝氏贾第鞭毛虫

91. Morphology Trophozoite Like badminton racket / “gost face” 2 discs
2 nuclei
4 pairs of flagella
Axostyles

92. G.lamblia trophozoite: using the trichrome stain the nuclei and the flagella are clearly visible. Trophozoites obtained by duodenal aspiration, trichrome stain.
G.lamblia trophozoite

93. Giardia lamblia trophozoite; approximate size = 14 µm
Giardia lamblia trophozoite; approximate size = 14 µm.  The two nuclei and clearly visible, but the characteristic "tear-drop" shape is not visible in this plane of focus. 来源

94. Another example of a Giardia lamblia troph
Another example of a Giardia lamblia troph.  The two nuclei are easy to see in this image.  (Original image from a Japanese language site tentatively titled "Internet Atlas of Human Parasitology." 来源
Another example of a Giardia lamblia trophozoite.  The two nuclei are easy to see in this image. 

95. Cyst
Ellipsoid
Wall
4 nuclei
Shrunken cytoplasm

96. 1 cyst containing 4 nuclei, rest of flagella and sucking disc.
Giardia lamblia: 1 cyst containing 4 nuclei, rest of flagella and sucking disc.  Stained fecal film. Wheatley modification of Gomori憇 trichrome technique.  Objective 100 X 
Courtesy of Daisy Zitova RNDr, Ph.D., Marek Bednar, MD, Ph.D.: Charles University, 3rd Medical Faculty,  Department for Medical Microbiology,  Ruska 87, Praha, Czech Republic.
Giardia lamblia cyst
1 cyst containing 4 nuclei, rest of flagella and sucking disc. 

97. The nuclei and axostyles are clearly visible.
Giardia lamblia cyst; approximate size = 14 µm.  The nuclei and axostyles are clearly visible. 来源
The nuclei and axostyles are clearly visible.

98. G.lamblia trophozoite: life cycle.

99. Main Points of Life Cycle
Host: human being
Residing site: small intestine
Infective stage: 4 nuclei cyst
Infective route: mouth

100. Clinical aspects Vomiting Flatulence Diarrhea Malabsorption syndrome
Cholecystitis

101. Diagnosis Examination of stool for trophozoite or cyst
Duodenal aspiration

102. Epidemiology Cosmopolitan Source of infection: carriers and patients
Transmission route: faeces----mouth
Susceptible population: traveler, AIDS patients, homosexual population

103. Prevention and Control
Patients and carriers: metronidazole
Water & nightsoil control
Insect vector control (fly, cockroach)
Personal hygienic health education

104. Opportunistic Protozoa

105. Opportunistic Parasite
Parasites which are not normally pathogens but become so due to impairment of host resistance.
These are assuming increasing clinical importance in AIDS epidemic.
Opportunistic protozoa
Toxoplasma gondii, Giadia lamblia, etc.

106. Toxoplasma gondii
刚地弓形虫

107. General Features A world wide distribution：1/3 population
Opportunistic parasite
Intracellular parasite
Zoonotic parasite

108. Life Cycle and Morphology
Two host pattern with alternation of generation
Definitive host: cat (acts also as I.H.)
Intermediate host: human being and other animals (herbivores, carnivores, omnivores)

109. Development in Cat Intestinal phase (sexual and asexual stage)
Schizogony merozoites (schizont)
Gametogony: micro and macrogametocyte  micro and macrogamete  zygote  oocyst
Sporogony: sporozoites (mature oocyst) (outside of the cat)

110. Development in Man Extraintestinal phase (asexual)
Infective stage
Oocyst
Tachyzoite
Cyst
Infective route: mouth
Residing site: tissue cells

111. 来源 http://www.cdfound.to.it/html/tox1.htm

112. T. gondii: lysis of a THP-1 cell with release of tachizoites in culture.
T. gondii: lysis of a THP-1 cell with release of tachizoites in culture. (Trophozoites in a THP-1 cell, Giemsa stain).
T. gondii: lysis of a THP-1 cell with release of tachizoites in culture.

113. T. gondii: microscopical features of tachizoites of Toxoplasma gondii and peritoneal macrophages of mouse in peritoneal exudate. (SEM)
Courtesy of dr. Dan STERIU Institutul Cantacuzino Splaiul Independentei 103,70100, Sector 6, Bucuresti, Romania.
Tachyzoites of Toxoplasma gondii in macrophages of mouse in peritoneal exudate. (SEM)

114. T. gondii: microscopical features of tachizoites of Toxoplasma gondii and peritoneal macrophages of mouse in peritoneal exudate. (SEM)
Tachyzoites of Toxoplasma gondii in macrophages of mouse in peritoneal exudate. (SEM)

115. T. gondii: in cell cultures T
T. gondii: in cell cultures T.gondii proliferates to form a pseudocyst of 8-20 parasites.
T. gondii: in cell cultures T.gondii proliferates to form a pseudocyst of 8-20 parasites. (Trophozoites in a THP-1 cell, Giemsa stain).
In cell cultures, T.gondii proliferates to form a pseudocyst of 8-20 parasites.

116. T. gondii: tissue cysts, 100-300 µm, may contain up to 3
T. gondii: tissue cysts, µm, may contain up to bradyzoites.
T. gondii: tissue cysts, µm, may contain up to bradyzoites. The wall of mature pseudocysts is believed to represent a combination of host and parasitic components.
T. gondii: tissue cysts, µm, may contain up to bradyzoites.

117. Pathogenesis
Acquired toxoplasmosis: eye lesion (uveitis, choroiditis, choroidoretinitis); lymphadenopathy
Congenital toxoplamosis:
Abortion;
Still birth (abnormities): hydrocephalus, mental retardation

118. Pathogenesis Toxoplamosis in immunoincompetent hosts Encephalitis
Pneumonitis
Myocarditis
Hepatitis, etc.

119. Diagnosis
Immunological diagnosis of specific IgG or IgM (first choice), eg: DT, ELISA, IFA, IHA, etc
Histological exams
Animal inoculation
PCR

120. Main Points Multi-cellular parasitism Transmission mode Congenital
I.H.  I.H
D.H  I.H
I.H  D.H

121. Epidemiology Cosmopolitan France: 45-85% Africa: 46% USA : 25-36%
China : 30%

122. Epidemiological Factors
Consuming raw or undercooked meat containing cyst
Contact with cats ( oocyst consumption)

123. Prevention Control
Drug: pyrimethamine +sulfadiazine spiramycin (for pregnant women)
Avoid contact with the cats ?
Avoid eat raw or undercooked meat