1. Introduction to Parasitology

2. What is Parasitology?
A parasite is an organism that live on or within another organism called the host .
Parasitology is a science of studying parasitism and a discipline dealing with the biology of parasites (including its morphology, embryology, physiology, biochemistry and nutrition, etc.), ecology of parasitism with emphasis on parasite-host and parasite-environment interactions.

3. the parasites studied in this discipline involve parasitic protozoa, parasitic helminthes, certain lesser groups of worms, parasitic arthropods, and the vectors of parasites, that is, parasitology is largely an amalgamation of protozoology, helminthology, entomology and acarology.
Parasitology has also been subdivided into medical or human parasitology, veterinary parasitology, fish parasitology and plant nematology

4. What is Medical Parasitology?
Medical parasitology or human parasitology is restricted to studying those parasites that are living in or on the body of humans and with aspects of the host-parasite relationship having medical significance. In other words, medical parasitology is the subject which deals with the parasites that infect man, the diseases caused by them, clinical picture and the response generated by man against them.

5. Parasites Parasitic diseases
Medical Parasitology
Parasites Parasitic diseases
Morphology
Life Cycle
Pathogenesis
Diagnosis
Treatment
Transmission
Prevention

6. Medical parasitology Medical protozoology Medical helminthology
Medical arthropodology
i.e. Medical entomology

7. Medical Parasitology in Medical Education
Public Health & Clinical
Preventive Medicine Medicine
Medical Parasitology
Biology,Biochemistry,Anatomy,
Histology,Physiology,Immunology

8. History of Human Parasitology
Early written records
3000 to 400 BC, the first written records of parasitic infections come from Egyptian medicine, particularly the Ebers papyrus of 1500 BC discovered at Thebes. Intestinal roundworms and tapeworms.
800 to 300 BC, writings of Greek physicians such as Hippocrates. Worms from fishes, domesticated animals, and humans.
3000 to 300 BC, writings of physicians from China.
2500 to 200 BC, from India.
700 BC to 400 AD, from Rome.
Latter part of the first millennium, from the Arab Empire.
Arabic physician Avicenna (AD 980 to 1037) , wrote important medical works that contain a great deal of information about diseases clearly caused by parasites. He recognized not only Ascaris, Enterobius, and tapeworms but also the guinea worm, Dracunculus medinensis.

9. History of Human Parasitology
Modern times
Manson in filariasis
Laveran in malaria parasite
Ross in 1897 malaria life cycle
Bruce in and Chagas in 1908 trypanosomiasis
Leishman and Donovan in leishmaniasis ……
1879 (Ringer) , 1880 (Manson) : Paragonimus westermani
1875 (McConnell) : Clonorchis sinensis
1905 (Logan) : Schistosoma japonicum in China

10. Patrick Manson(1844-1922) “Father of modern tropical medicine”
In England Manson became Medical Advisor to the Colonial Office and in this capacity persuaded the then Secretary of State for the Colonies, Joseph Chamberlain, of the need for providing facilities in Britain for educating doctors in tropical diseases. One consequence of his influence was the creation of School of Tropical Medicine in both Liverpool and London in 1898
Patrick Manson( ) “Father of modern tropical medicine”
The first President (and Ronald Ross Vice-President) of the Society of Tropical Medicine and Hygiene (1907)
The first to discover (1877–79) that an insect (mosquito) can be host to a developing parasite (the worm Filaria bancrofti) that is the cause of filariasis

11. 1907 Nobel Laureate in Medicine
in recognition of his work on the role played by protozoa in causing diseases
Alphonse Laveran
1902 Nobel Laureate in Medicine
for his work on malaria, by which he has shown how it enters the organism and thereby has laid the foundation for successful research on this disease and methods of combating it
Ronald Ross

12. Conceptions related to medical parasitology
Symbiosis
Parasite and type of parasites
Host and common type of host
Life cycle and type of life cycle

13. Symbiosis
The relationship between two living things (animals). Two living things live together and involve protection or other advantages to one or both partner.
Commensalism
Mutualism
Parasitism

14. Commensalism
Both partners are able to lead independent lives, but one may gain advantage from the association when they are together and least not damage to the other
A female pea crab in the mantle cavity of its mussel host. The crab does not damage the mussel and uses its shell purely for protection
Mussel

15. Mutualism An association which is beneficial to both living things
A selection of ciliates from the rumen of cattle or sheep. The rumen contains enormous numbers of ciliates that break down cellulose in the feed

16. Parasitism
An association which is beneficial to one partner and harmful to the other partner. The former that is beneficial to is called parasite, the latter that is harmful to is called host. e.g., Human / Hookworm
Anterior end of a hookworm

17. Other classification
Parasites may be classified according to different ways:
Obligate parasite: a parasite which cannot survive in any other manner, e.g., filaria
Facultative parasite: an organism which may exist in a free-living state and which if opportunity presents itself may become parasitic, e.g., Strongyloides stercoralis

18. Endoparasite and ectoparasite
A parasite which lives in or on the body of the host is called endoparasite (protozoa and helminthes) or ectoparasite (arthropods)

19. Host and type of host
Host : an organism that harbors the parasite usually larger than the parasite
Intermediate host : the host harboring the larvae or asexual stage of parasite
Final host (definitive host) : the host harboring adult or sexual stage of parasite

21. Host and type of host
Reservoir host : animals harboring the same species of parasites as man, e.g., schistosome/human, buffalo
Potential sources of human infection
Paratenic host (transport host) : a host which acts as a transporting agent for the parasite and in which, the parasite, usually a larval stage, dose not undergo any further development but if they could go into a final host by accident it would continue to develop till sexual maturity, e.g., Paragonimus Westermani /human, wild boar

22. Life cycle and type of life cycle
Life cycle : the whole biological course of growth, development and reproduction of a parasite
The direct type : only one host (final host, no intermediate host). e.g., Ascaris lumbricoides, Hookworm, and Enterobius vermicularis
The indirect type : life cycle with more than one host (intermediate host and final host) . e.g., plasmodium, lymphatic filaria

25. Classification of parasites
Protozoa Parasites Helminthes Arthropods
(Unicellular)
(Multicellular )
Nematodes
Trematodes
Cestodes
(Endoparasite)
(Ectoparasite)

26. Protozoa
Plasmodium
RBC

28. Ciliates, Coccidia, Blastocystis Blood-Borne Protozoa
Amebae (found in stool)
Entamoeba coli
Entamoeba histolytica
Endolimax nana
Iodamoeba butschlii
Dientamoeba fragilis
Flagellates (found in stool)
Giardia lamblia
Chilomastix mesnili
Ciliates, Coccidia, Blastocystis
Balantidium
Cryptosporidium
Isospora belli
Sarcocystis
Cyclospora
Microsporidium
Blastocystis hominis
Blood-Borne Protozoa
Babesia
Leishmania
Trypanosoma brucei
T. cruzi
Plasmodium
Other
Toxoplasma
Naegleria fowleri
Acanthamoeba

29. Intestinal and luminal protozoa significant to human health include
Entamoeba histolytica (Amoebae)
Balantidium coli (Ciliates)
Giardia lamblia and Trichomonas vaginalis (Flagellates)
Cryptosporidium parvum and Isospora belli (Sporozoa)

30. Protozoa Found in Stool: Amebae
pathogen

31. Entamoeba histolytica/dispar
E. histolytica is a pathogen and E. dispar is a nonpathogenic species that can also occur in the large intestine. Morphologically indistinguishable
E histolytica
Cysts = infectious form
trophozoites = invasive form
Contaminated water and poor sanitation
Colon biopsy shows “flask-shaped” ulcer
Non-intestinal disease = extraintestinal amebiasis (liver abscess)
Serology

33. Entamoeba histolytica/dispar
Cysts <= 10 um
In diameter
Up to 4 nuclei in
the cyst
Clean chromatin
Bulls-eye nucleoli

34. Amebic abscess Amebic liver abscess Entamoeba histolytica
Serology – high % positive in extra-intestinal cases
Flask-shaped ulcer of intestinal amebiasis

35. Entamoeba histolytica/dispar
Trophozoites & Cysts
Trophozoite with ingested rbcs

36. Entamoeba coli
Trophozoites & Cysts

37. Entamoeba coli cyst and trophozoite
Trophozoite is the form that invades intestines
Cyst >=15 mm
Up to 8 nuclei
Shed from host
Lives in environment
Nucleus has a chromatin ring
The cytoplasm appears dirty

38. Protozoa Found in Stool: Flagellates

39. “falling leaf” motility
Giardia lamblia
Contaminated water, undercooked foods
Mild diarrhea to severe malabsorption
Foul, watery diarrhea
Day-care center outbreaks
Cysts/trophozoites may be seen in stool, but can be hard to find; Fluorescent stains available
Duodenal aspirations
CYSTS
TROPHOZOITE
“falling leaf” motility

40. Giardia lamblia trophozoite
Waxing and waning
symptoms
Can be irregularly
Shed in stool material
& can be difficult to find
Russia & Mexico
-Hot beds
Only invades intestine
Flagyl (Metronidazole)
is drug of choice

41. Giardia lamblia cysts

42. Giardia lamblia cysts

43. Giardia lamblia trophozoites

44. Trichomonas vaginalis
Urogenital protozoan
Scant, watery vaginal discharge
Four flagella, short undulating membrane

45. Protozoa Found in Stool: Ciliates, Coccidia, Blastocystis

46. Ciliates Balantidium coli Mainly in swine
Contact with swine & poor hygiene
Only ciliate that’s pathogenic to humans
Similar disease as amebiasis, but extraintestinal invasion rare
Largest ( um) trophozoite; surface covered with cilia; macronucleus
Cyst um
Readily identified in fresh, wet mounts

47. Only protozoa with cilia
50 microns
In intestine can cause flask-shaped ulcers like those caused by E. histolytica

48. Blood-Borne Protozoa None; self resolving. Maltese cross in rbc
Hemolytic anemia, Jaundice, fever, hepatomegaly
Ixodes tick
Babesia microti
Pentosam; Pentamidine isethionate.
Intracellular (macrophages) leishmanial bodies with kinetoplast
Visceral leishmaniasis (Kala-azar), granulomatous skin lesions
Iraq/Iran/Afghanistan
Phlebotomine sandfly
Leishmania donovani
CNS: melarsoperol Nifurtimox and Benzonidazole.
Hemoflagellate in blood or tissue.
C- or comma-shaped
American trypanosomiasis;
Chagas disease: megacolon, cardiac failure.
Reduvid (kissing) bug
T. cruzi
Blood stage: Suramin or petamidine isethionate
Hemoflagellate in blood or lymph node
African trypanosomiasis; Sleeping sickness
Encephalitis; cardiac failure
Tsetse fly
Trypanosoma brucei
Treatment
Diagnosis
Disease/Symptoms
Transmission
Organism

49. Trypanosomes 2 different diseases
Chagas disease (American trypanosomiasis)
Trypanosoma cruzi
Reduviid / Triatome (kissing) bug
African sleeping sickness (African trypanosomiasis)
T. brucei (gambiense and rhodesiense)
Tsetse fly

50. Trypanosoma brucei  Sleeping sickness (African trypanosomiasis)
Vector: Tsetse fly
The two T. brucei species that cause African trypanosomiasis are indistinguishable morphologically 
T. b. gambiense
T. b. rhodesiense
A typical trypomastigote has:
A small kinetoplast located at the posterior end
A centrally located nucleus
An undulating membrane, and
A flagellum running along the undulating membrane, leaving the body at the anterior end
14 to 33 µm in length
Trypomastigotes are the only stage found in patients. 

51. Trypanosoma brucei gambiense in a blood film
Filamentous structures found in blood

52. TRYPANOSOMA GAMBIENSE

53. Leishmania Obligate intracellular parasite
Vector: female sand fly bite
Visceral leishmaniasis (kala azar)
L. donovani
Cutaneous leishmaniasis
L. tropica
L. braziliensis

54. Leishmania

55. Leishmania amastigotes
Macrophages filled with amastigotes (arrows), several of which have a clearly visible nucleus and kinetoplast
Amastigotes are being freed from a rupturing macrophage

56. Leishmania – Clinical Disease
Cutaneous
Single or few chronic, ulcerating lesions; many species
Latin America, southern Europe, Middle east, southern Asia, Africa
Mucocutaneous in Latin America
Visceral
primarily L. donovani complex (Asia), L. infantum/chagasi (Africa and Latin America), others
Hepatosplenomegaly, anemia, cytopenias, systemic symptoms
India, Bangladesh, Nepal, Sudan, and Brazil
Important OI in HIV infection

57. Leishmania donovani
Kinetoplast next to nucleus
Skin lesion
Sand Fly

58. MALARIA Protozoan Transmitted by the anopheles mosquito
Endemic to tropical areas
Blackwater fever (falciprium and think black pee) 58

59. Malaria Symptoms Fever and chills Splenomegaly Headache Abdominal pain
Diarrhea
Myalgia
Blackwater fever (hemolysis, hemoglobinuria, renal failure) – P falciparum only

60. Malaria Distinction is between P. falciparum and non-falciparum
P. falciparum = rapidly progressive and LETHAL (malignant tertian fever), often chloroquine-resistant
Non-falciparum = rarely cause severe manifestations, often chloroquine sensitive
Relapsing malaria
Dormant hepatic phase
Hypnozoites of P. vivax and P. ovale
Exception for non-falcirpium is P. vivax where chlorquine resistance is seen in Papua New Guinea and Indonesia 60

61. MALARIA Life Cycle of Plasmodium Species
The malaria parasite life cycle involves two hosts.  During a blood meal, a malaria-infected female Anopheles mosquito inoculates sporozoites into the human host.  Sporozoites infect liver cells and mature into schizonts, which rupture and release merozoites.  (Of note, in P. vivax and P. ovale a dormant stage [hypnozoites] can persist in the liver and cause relapses by invading the bloodstream weeks, or even years later.)  After this initial replication in the liver (exo-erythrocytic schizogony ), the parasites undergo asexual multiplication in the erythrocytes (erythrocytic schizogony ).  Merozoites infect red blood cells .  The ring stage trophozoites mature into schizonts, which rupture releasing merozoites.  Some parasites differentiate into sexual erythrocytic stages (gametocytes).  Blood stage parasites are responsible for the clinical manifestations of the disease.  The gametocytes, male (microgametocytes) and female (macrogametocytes), are ingested by an Anopheles mosquito during a blood meal .  The parasites’ multiplication in the mosquito is known as the sporogonic cycle .  While in the mosquito's stomach, the microgametes penetrate the macrogametes generating zygotes .  The zygotes in turn become motile and elongated (ookinetes) which invade the midgut wall of the mosquito where they develop into oocysts .  The oocysts grow, rupture, and release sporozoites , which make their way to the mosquito's salivary glands.  Inoculation of the sporozoites into a new human host perpetuates the malaria life cycle . 
Life Cycle of Plasmodium Species 61

62. Malarial Preparations
Thick smear
Drop of blood on slide
Water rinse to eliminate rbc’s
Stain with Giemsa stain (not Wright-Giemsa) with proper pH
Concentrated to spot malaria parasites
Thin smear
Feather edge smear
For optimal morphology, stain with Giemsa (not Wright-Giemsa) stain with proper pH
Speciation of malaria
Parasitemia (%)

63. Malaria Diagnosis Microscopy is most often used
Antigen detection – EIA available
Molecular methods

64. Most prevalent
Widest geographical distribution 64

65. Enlarged RBC; fimbriated/ragged rbc65

66. Fever cycle every 72 hours (quartan), can remain dormant in the blood for years.
Untreated infections may last as long as 20 years
“Rosette” schizont 66

67. Other Protozoa
Toxoplasma

68. Toxoplasma gondii Organism Transmission Disease/Symptoms Diagnosis
Treatment
Toxoplasma gondii
Oral from cat fecal material
or meat
Adult: flu like;
congenital: abortion, neonatal blindness and neuropathies
Intracellular (in macrophages) tachyzoites
Sulphonamides, pyemethamine, possibly spiramycin (non-FDA)

69. Toxoplasma gondii Coccidian protozoan House cat = definitive host
Ingestion of infective oocysts from contaminated cat feces
Ingestion of improperly cooked meat from animals that serve as intermediate hosts (rodents)
Symptoms
Predilection for lung, heart, lymphoid organs, CNS/eye
Infectious mono-like; lymphadenitis, hepatitis, rash, encephalomyelitis, myocarditis, chorioretinitis
Transplacental infection
1st trimester  spontaneous abortion, stillbirth or severe disease
2nd/3rd trimester  CNS infections (epilepsy, encephalitis, intracranial calcifications, MR, chorioretinitis, blindness, hearing loss), jaundice, rash
AIDS - Encephalitis; mass lesions in brain

70. Toxoplasma gondii Diagnosis Serology EIA PCR
Anti-toxo IgM – congenital and acute infection; may persist for months
Anti-toxo IgG – common; if positive, gestations safe from intrauterine toxoplasmosis infection
PCR

71. Toxoplasma gondii
Can be diagnosed by serology

72. Toxoplasma gondii
Toxoplasma gondii cyst in brain tissue stained with hematoxylin and eosin

74. HELMINTHS Nematodes (roundworms) Trematodes (flukes)
Cestodes (tapeworms)

75. Nematodes Enterobius Ascaris Trichuris
Necator and Ancylostoma (Hookworm)
Microfilaria – Wucheria, Brugia, Loa loa, Mansonella, and Onchocerca

76. Enterobius vermicularis (pinworm)
Humans considered only host
Females 8-13mm, males 2-5 mm
Dwell in the cecum
¼-1/2 inch in thickness, white, lloks like string in stool
Lay up to 15,000 eggs
Oval with a flattened side: 50-60um by 20-30um
Diagnosis- Scotch tape test or anal swab
Most common helminth in US

77. Enterobius vermicularis (pinworm) eggs
Asymmetrical eggs

78. Pinworm larvae

79. Ascaris lumbricoides (roundworm)
1-1.2 billion people infected
More common in children
20,000 death
Largest helminth to affect humans
Females 20-35cm long, males 15-30cm with a curved tale
Can cause intestinal obstruction

80. Ascaris lumbricoides

81. Ascaris eggs Unfertilized eggs-large & oval, mammillated
layer is pronounced
Fertilized eggs- smaller, rounder,
mammillated layer is less obvious

82. Trichuris Trichiura (whipworm)
Soil transmitted
Can be similar to amebiasis
PVA preserved samples inferior to formalin
Adults attach to large intestine and are rarely recovered
Thinnest part- head
Males are smaller than females

83. Trichuris trichiura

84. Necator americanus, Anclyostoma duodenale (Hookworms)
Soil transmitted
2nd most common helminth infection
Enter via exposed skin
Necator or Ancylostoma – Hookworm egg

85. Trichinella spiralis Tissue nematode All stages occur in single host
-usually an incidental finding
in muscle

86. Loa loa (eye worm)

87. Trematodes (Flatworms)
Intestinal and Liver flukes
Fasciolopsis buski
Fasciola hepatica
Liver flukes
Clonorchis sinensis (Chinese liver fluke)
Paragonimus westermani – oriental lung fluke
Schistosomes
S mansoni – intestinal bilharziasis
S haematobium - urinary
S japonicum – blood fluke, found in intestines

88. Trematodes ( Flukes )
Schistosomes

89. Schistosoma japonicum, mansoni

90. Fasciolopsis buski ( Giant intestinal fluke)

91. Distinct nose
Fasciola hepatica

92. Fasciolopsis buski
Fasciola hepatica

93. Fasciolopsis buski
Fasciolopsis buski

94. Cestodes (Tapeworms) Examples Diphyllobothrium latum Taenia saginata
Flattened dorsoventrally, segmented
Head with armed or unarmed scolex
Proglottids immature, mature (sex organs)
Gravid (with eggs)
Internal structure of proglottids
Hermaphroditic-ovary, testes, vitellaria,
uterus, genital pore and ducts
Lateral excretory and nervous system
No gut-tegument absorbs nutrients
Muscles-longitidinal and horizontal
Examples
Diphyllobothrium latum
Taenia saginata
Taenia solium
Hymenolepis nana
Hymenolepis diminuta
Echinococcus granulosis

95. Diphyllobothrium latum
Poorly-cooked fresh-water fish(salmon)
Scandinavian, Russia, Canada, N. USA, Alaska
Broad fish tapeworm
Longitudinal sucker
Eggs have non-shouldered operculum and knob
They are not embryonated
Causes Vit B12 deficiency

96. Diphyllobothrium latum

97. Sucking plate
Diphyllobothrium latum

98. Taenia Species – two species Outstanding characteristics
Taenia Solium
Pig tapeworm
Ring of thorns/crown on scolex
<13 uterine branches in proglottids
Ingestion of cysticerci in pork
Intestinal infestation
Ingestion of eggs ->
Cysticercosis
Taenia saginata
Beef tapeworm
4 suckers on scolex
>13 uterine branches in proglottids
Ingestion of cysticerci in beef
Intestinal infestation
Ingestion of eggs ->
Non-human pathogen

99. Taenia eggs
Identical eggs for the two species

100. Taenia saginata
Proglottid > 12 uterine branches

102. Taenia solium Scolex - Ring of thorns
Proglottis – fewer uterine branches
(<=12 uterine branches)

103. Medical arthropods
Fly
Sandfly
Mosquito
Soft tick
Hard tick
Louse
Flea

104. Maggots
Bot fly larvae
Extrudes from the skin

105. Ticks of importance Soft tick - Expands with blood engorgement
Hard Ticks
Soft tick -
Expands with blood
engorgement

106. Hour glass
On tummy
Black Widow spider

107. Body louse
Body Louse
Hair nit
Flea
Crab louse

108. Tiny eggs under skin
Mite
Scabies

109. THANK YOU