1) The document describes various intestinal parasites including their infective stages, definitive hosts, mode of transmission, habitat within the host, and pathogenic stages. 2) Key details are provided to identify parasites microscopically such as their eggs, larvae, and adult stages. 3) The parasites discussed cause diseases by mechanisms such as obstruction, inflammation, necrosis, and toxemia by attaching and feeding within the host's intestines and tissues.

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Genus and Species Entamoeba histolytica Entamoeba coli Endolimax nana Iodamoeba buetschlii
Infective Stage: Cyst Cyst Cyst Cyst
IMAGE
Total no. of nucleus 1-4 1-8 1-4 Usually 1
Diagnostic feature Bull’s eye karyosome Jagged or splintered ends
chromatoidal bodies
Ground glass appearance;
cross-eyed karyosome
2/3 glycogen vacuole; “Iodine
cyst of Wenyoun”
Chromatoidal body Cigar-shaped Whisk broom Comma-bacilliform
Definitive Host Man Man Man Man
P.O.E Mouth Mouth Mouth Mouth
M.O.T Ingestion of mature cyst thru
contaminated water or food
Ingestion of mature cyst thru
contaminated water or food
Ingestion of mature cyst
thru contaminated water or
food
Ingestion of mature cyst thru
contaminated water or food
Habitat Cecum Cecum Cecum Cecum
Pathogenic Stage Trophozoite Trophozoite Trophozoite Trophozoite
IMAGE
Diagnostic feature Ingested RBC Dirty cytoplasm 1/3 glycogen vacuole
Locomotive apparatus Pseudopodia
(“finger-like”)
Pseudopodia
(“short and blunt”)
Pseudopodia
(“finger-like)
Pseudopodia
(“short and blunt”)
Motility Active, Progressive, Directional Sluggish, Non-progressive nor
directional
Sluggish Sluggish but may be
progressive
Mechanism of disease
production
Lytic Necrosis

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Genus and Species Giardia lamblia Chilomastix mesnili Trichomnas vaginalis Dientamoeba fragilis Balantidium coli
Infective Stage: Cyst Cyst Trophozoite Trophozoite Cyst
IMAGE
Total no. of nucleus 4 1
Diagnostic feature Retracted cytoplasm; 4
pairs of axoneme
Nipple-like projection;
Lemon-shaped
Siderophil granules Tetracoccic appearance
of karyosome
Bean/Kidney-shaped
macronucleus
perpendicular to
micronucleus
Number of Flagella 8 4 5 (2pairs and 1
undulating membrane
Definitive Host Man Man Man Man Man
P.O.E Mouth Mouth Genitalia Mouth Mouth
M.O.T Ingestion of mature cyst
thru contaminated
water or food
Ingestion of mature cyst
thru contaminated
water or food
Sexual intercourse Ingestion of mature cyst
thru contaminated
water or food
Ingestion of mature cyst
thru contaminated
water or food
Habitat Duodenal crypts Cecum Vagina, Prostate gland Cecum Cecum
Pathogenic Stage Trophozoite Trophozoite Trophozoite Trophozoite
IMAGE
Diagnostic feature Ventral sucking disc Spiral groove Bean/Kidney-shaped
macronucleus
Locomotive apparatus Flagella Flagella Flagella Pseudopodia Cilia
Motility Falling-leaf-like Corkscrew Boring motion Jerky, Tumbling Directional, Tumbling
Mechanism of disease
production
Coating/Carpeting of
the wall
Vaginal pruritis Lytic Necrosis

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Genus and Species Plasmodium falciparum Plasmodium vivax Plasmodium ovale Plasmodium malariae
Etiologic Agent Malignant/ Sub tertian Benign Tertian Ovale malariae Quartan malariae
IMAGE
BAND form
ROSETTE
Host RED CELL Normal-sized Enlarged Normal-sized
Definitive Host Anopheles mosquito MOT BLOOD, Mosquito bite
Infective Stage to DH Gametocytes HABITAT RBC
Intermediate Host MAN Pathogenic Stage MEROZOITE/Trophozoite
Infective Stage to IH SPOROZOITE Mechanism of disease
production
Tissue Anoxia
POE Skin

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NEMATODES ( Adenophorea)
Genus and Species Trichuris trichiura Trichinella spiralis Capillaria philippinensis
Common Name Whip worm Trichina worm Pudok worm
Intermediate Host Flies, Rat Man Panstrongylus (Triatomid/Kissing
bug)
Definitive Host Man Pigs/ Rats Man
P.O.E Mouth Mouth Mouth
M.O.T Ingestion thru contaminated food and drink Ingestion thru contaminated pork Ingestion thru contaminated fish
Habitat Large Intestine Small Intestine Small Intestine
Infective Stage Embryonated egg Encysted Larva L3 Larva
IMAGE
EGG- Diagnostic Bipolar mucus plug; Football shaped;
Japanese lantern
Flat mucus plugs; Coarsely pitted
eggshell; Peanut shaped
Pathogenic Stage Adult Encysted Larva Adult
IMAGE
ADULT- Diagnostic MALE- 360 degree caudal MALE- conspicuous papillae
FEMALE- uterus with semi-coiled larva
MALE- overhanging sheath with
long copulatory spicule
FEMALE- uterus filled with eggs
Attachment and
nutrition
Anchorage
Pathogenesis Rectal prolapsed Myocarditis Malabsorption of nutrients

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Genus and Species Toxocara canis Toxocara cati Ancylostoma caninum Angiostrongylus
cantonensis
Gnathostoma
spinigerum
Common Name Dog Ascarid Cat Ascarid Dog Hookworm Rodent Lungworm
Etiologic Agent Visceral Larva Migran Visceral Larva Migran Cutaneous Larva Migran Eosinophilic meningitis Gnathostomiasis
Intermediate Host Man Man Dog Snail; Rat Cyclops- fish
Definitive Host Dog Cat Man Man as accidental host Man as accidental host
POE Mouth Mouth Skin Mouth Mouth
MOT Ingestion Ingestion Skin penetration Ingestion; Skin
penetration;
Transplacental
Ingestion
HABITAT Tissues, Organs Tissues, Organs Cutaneous Tissues, Organs Tissues, Organs
Infective Stage Egg Egg Filariform Larva L3 L3
IMAGE
EGG
EGG-Diagnostic Coarsely pitted shell Finely pitted eggshell
Pathogenic Stage Larva Larva Larva Larva Larva
IMAGE
ADULT-Diagnostic Cervical alae- longer than
broad
Cervical alae- broader
than long
3 pairs of large teeth Barber’s pole
appearance
Disease production Granulomatous reaction Granulomatous reaction Creeping eruption Granulomatous reaction Granulomatous reaction

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Genus and Species Ascaris lumbricoides Necator americanus Ancylostoma duodenale
Common Name Giant intestinal roundworm New World hookworm Old Worm hookworm
Definitive Host Man Man Man
POE Mouth SKIN > Mouth MOUTH > Skin
MOT Ingestion More of Skin penetration More of ingestion
HABITAT Small intestine Small intestine Small intestine
Infective Stage Embryonated egg Filariform larva Filariform larva
IMAGE
Unfertilized Fertilized Decorticated Filariform Rhabditiform -SAME as N. americanus-
EGG
EGG- Diagnostic Coarse mammilated albuminous coating In morula In morula
Pathogenic Stage Adult larva Adult larva Adult larva
IMAGE
FEMALE MALE BUCCAL COPULATORY BUCCAL COPULATORY
ADULT- Diagnostic FEMALE- prominent genital girdle Semi-lunar cutting plate;
Bipartite dorsal ray
MALE- Tripartite dorsal ray
Disease production ADULT- Obstruction; Perforation; Occlusion

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Genus and Species Strongyloides stercoralis Enterobius vermicularis
Common Name Threadworm Pinworm, Seatworm, Society worm
Etiologic Agent Cochin-china disease Oxyuriasis, Enterobiasis
Definitive Host Man Man
POE Skin Mouth or Nose
MOT Skin infection; “AUTOINFECTION” Ingestion, Inhalation, “AUTOINFECTION”
HABITAT Small intestine CECUM
Infective Stage Filariform larva Embryonated egg
IMAGE Filariform Rhabditiform
EGG- Diagnostic Lopsided appearance, letter “D”
Pathogenic Stage Adult larva Adult
IMAGE Parasitic FEMALE FEMALE MALE
ADULT- Diagnostic Filariform larva- bifid or notched end Bulbous esophagus with cephalic alae
Mechanism of disease production LARVA- dew itch, creeping eruption
ADULT- mechanical, chemical irritation, abdominal
disturbance
Vaginitis; Nocturnal pruritis ani

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Genus and Species Wuchereria bancrofti Brugia malayi Loa loa
Common Name Bancroft’s filarial worm Malayan filarial worm Loa/Eye worm
Vector/s Anopheles, Aedes, Mansonia species;
Culex fatigans
Mansonia sp, Aedes togoi, Anopheles
species
Chrysops dimidia and silacea
(day-biting fly)
POE Skin Skin Skin
MOT Insect bite Insect bite Insect bite
HABITAT Lymphatics Lymphatics Sub/cutaneous tissue
Infective Stage L3 L3 L3
Pathogenic Stage Dead and Living Adult worms Dead and Living Adult worms Adult worms
IMAGE
Diagnostic Characteristic Sheated Sheated Sheated
Mechanism of disease production Lymphatic Obstruction Lymphatic Obstruction
Periodicity Nocturnal Nocturnal Diurnal

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LIVER FLUKES LUNG FLUKE
Genus and
Species
Fasciola hepatica Clonorchis sinensis Opistorchis felineus Paragonimus westermani
Common
Name
Sheep Liver fluke Chinese liver fluke Cat liver fluke Oriental Lung fluke
Developmental
Stage
SRRC SRC SSRC SRC
2nd
IH Watercress Fresh-water fishes Fresh-water fishes Crabs
Infective Stage
to 2nd
IH
Cercaria Cercaria Cercaria Cercaria
Definitive Host Man Man Man Man
Infective Stage
to DH
Metacercaria Metacercaria Metacercaria Metacercaria
POE Mouth Mouth Mouth Mouth
MOT Ingestion Ingestion Ingestion Ingestion
HABITAT Proximal Biliary tract Distal Biliary tract Distal Biliary tract Pulmonary pockets
Pathogenic
Stage
Mature/Young Adult Adult Adult Mature/Young Adult
IMAGE
Fluke
characteristic
Cephalic cone 2 Highly branching testes at
posterior 3rd
Transversely compressed
vitellaria
Zigzag intestinal ceca
EGG
characteristic
Non-embryonated; Hen’s egg Embryonated; Old-fashion light bulb Embryonated; Old-fashion light
bulb
Non-embryonated; thick
aboperculum
IMAGE
Mechanism of
dse prod
Mechanical/Toxic effect;
Fascioliasis
Obstruction; Inflammation Obstruction; Inflammation Abscess

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INTESTINAL FLUKES
Genus and Species Fasciolopsis buski Echinostoma ilocanum Heterophyes heterophyes
Haplorchis yokogawai (1 testes)
Metagonimus yokogawai
Common Name Giant intestinal fluke Garrison’s fluke Yokogawai’s fluke
Developmental Stage SRRC RRC SRC
2nd
IH Snail (Pila conica/kuhol) Snail Fresh-water fishes
Infective Stage to 2nd
IH Cercaria Cercaria Cercaria
Definitive Host Man Man Man
Infective Stage to DH Metacercaria Metacercaria Metacercaria
POE Mouth Mouth Mouth
MOT Ingestion Ingestion Ingestion
HABITAT Small intestine Small intestine Small intestine
Pathogenic Stage Adult Adult Adult
IMAGE H.heterophyes H.yokogawai M.yokogawai
Fluke characteristic NO Cephalic cone Circumoral disc
EGG characteristic Non-embryonated; Hen’s egg With germ-ball; dark triangular
operculum
Embryonated; Old-fashion light bulb
IMAGE
Mechanism of dse prod Obstruction, Traumatic,
Toxemia
Obstruction, Mechanical,
Toxemia
Myocarditis

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BLOOD FLUKES
Genus and Species Schistosoma haematobium Schistosoma japonicum Schistosoma mansoni
Common Name Visceral Blood fluke Oriental Blood fluke Manson’s Blood fluke
1st
IH Bulinus sp. Oncomelania quadrasi Biomphalaria
Infective Stage of 1st
IH
Miracidium Miracidium Miracidium
Dev’tal Stage SSC SSC SSC
Definitive Host Man Man Man
Infective Stage DH Cercaria Cercaria Cercaria
POE Skin Skin Skin
MOT Skin penetration Skin penetration Skin penetration
HABITAT VESICAL and PELVIC plexus SUPERIOR mesenteric plexus INFERIOR mesenteric plexus
Pathogenic Stage Cercaria, Adult, Egg Cercaria, Adult, Egg Cercaria, Adult, Egg
IMAGE
ADULT EGG ADULT EGG ADULT EGG
FLUKE Characteristic MALE- late union of intestinal ceca
FEMALE- post.-mid plane of ovary
MALE- very late union
FEMALE- a bit behind the mid-plane
MALE-early union
FEMALE- ant.-mid plane of ovary
EGG Characteristic TERMINAL spine Abbreviated LATERAL spine Prominent LATERAL spine
Mechanism of dse
prod
Allergic; Obstruction Allergic; Obstruction Allergic; Obstruction

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CYCLOPHYLLIDEA
Genus and Species Hymenolepis nana Hymenolepis diminuta Dipylidium caninum Echinococcus granulosus
Common Name Dwarf tapeworm Rat tapeworm Double-pored dog tapeworm Echinococcosis
IH Man Flees, Beetles Herbivores (cows,ships) Herbivores (cows, ships)
Infective Stage to IH Embryonated egg Embryonated egg Embryonated egg
DH Man Man Man Dog, Sheep
Infective Stage to
DH
Embryonated egg Cysticercoid larva Cysticercoid larva Hydatid cyst
POE Mouth Mouth Mouth Mouth
MOT Ingestion Ingestion Ingestion Ingestion
HABITAT Small intestine (ileum) Small intestine (ileum) Small intestine (ileum) Tissues, Organs
Pathogenic Stage Adult Adult Adult Hydatid cyst
IMAGE
MATURE MATURE MATURE ADULT: CYST:
GRAVID GRAVID GRAVID
Characteristic Scolex-ARMED rostellum
3 ovoid testis
Scolex- UNARMED rostellum
3 ovoid testis
Pumpkin-seed shape
EGG IMAGE
Characteristic Polar thickening (4-8 polar
filaments)
Polar thickening (w/o polar
filaments)
Mother pocket with 8-15
eggs
Mechanism of
disease production
Autoinfection; Irritation;
intestinal disturbance
Irritation; intestinal disturbance Irritation; intestinal
disturbance
Toxic; Mechanical

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CYCLOPHYLLIDEA
Genus and Species Taenia saginata Taenia solium
Common Name Beef tapeworm Pig tapeworm
1st
IH Cattle Pig
Infective Stage to IH Embryonated egg Embryonated egg
DH Man Man
Infective Stage to DH Cysticercus bovis Cysticercus cerulosae
POE Mouth Mouth
MOT Ingestion of improperly cooked 2nd
IH Ingestion
HABITAT Small intestine Small intestine
Pathogenic Stage Adult Adult
IMAGE
MATURE MATURE
GRAVID GRAVID
Characteristic Scolex-NO rostellum; UNARMED
Mature: NO accessory ovary
Gravid: 18-20 lateral branches (long and thin)
Scolex- rostellum with 2 hooklets
Mature: WITH accessory ovary
Gravid: 7-13 lateral branches (short and stout)
EGG IMAGE
Characteristic Mature; non-operculated Mature; non-operculated
Mechanism of
disease production
Irritation; intestinal disturbance Irritation; intestinal disturbance; Autoinfection

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PSEUDOPHYLLIDEA
Genus and Species Diphylobothrium latum
Common Name Broad or Fish tapeworm
Etiologic Agent of: Diphylobothriasis Sparganosis
2nd
IH Freshwater fish Man
Infective Stage to 2nd
IH
Plerocercus larva Plerocercus larva
Definitive Host MAN
Infective Stage to DH Plerocercoid/ Sparganum
POE MOUTH
MOT Ingestion of Sparganum
HABITAT Small intestine Tissues, Organs
Pathogenic Stage ADULT LARVA
IMAGE
ADULT MATURE
Adult tapeworm SCOLEX- Spatulated with bothria
EGG IMAGE
Mechanism of
disease production
PERNICIOUS and MEGALOBLASTIC ANEMIA

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