Parasite
Organism Entamoeba histolytica
Other species include: -
➢ E. coli – 8 nuclei
➢ E. dispar
➢ E. moshkovskii
➢ E. polecki
➢ E. hartmanni
➢ E. gingivalis
Disease Amebic dysentery & liver abscess
Morphology Protozoa (amoeba) – intestinal
Mobile trophozoites – inside GIT, extraintestinal lesion & diarrheal stool
➢ Single nucleus
➢ Even lining of peripheral chromatin
➢ Prominent small central nucleolus
➢ Fine chromatin granule along border of nuclear membrane
Non-motile cyst – 4 nuclei & outside body
➢ Smaller than most other ameba
Epidemiology More common in tropics
MOT Fecal-oral route – ingestion of cyst
Anal-oral route
X animal reservoir
RF ➢ Poor hygiene
➢ Homosexual
Life cycle Cyst excystation in ileum
➢ Ameba w 4 nuclei emerge → 8 trophozoites
➢ Mature trophozoites colonize cecum & colon
Pathogenesis Trophozoites invade the colonic epithelium
➢ Secrete enzyme causing localized necrosis
➢ Little inflammation occurs
➢ As lesion reaches the muscularis layer – flask-shaped ulcer forms
Progression into submucosa
➢ Invasion of portal circulation
➢ Reach liver to cause abscess
S&S 90% asymptomatic & become carrier
Acute
Dysentery (bloody & mucus containing diarrhea)
Lower abdominal discomfort
Flatulence
Tenesmus
Chronic
Occasional diarrhea
Weight loss
Fatigue
Amebic abscess
RUQ pain
Weight loss
Fever
Tender & enlarged liver
Complication Ameboma (mistaken for adenocarcinoma)
➢ Granulomatous lesion in cecal/rectosigmoid
Lung disease
➢ R lobe abscess from liver penetrate diaphragm → lungs
Dx Diarrheal/formed stool sample
➢ Trophozoites & cyst found respectively
➢ Trophozoites can be seen moving w ingested RBC
At least 3 sample of stool
Serology Ag
PCR
Wet mount, iodine stained wet mount & fixed trichrome stained – distinguish amebic from bacillary dysentery (bacillary ↑PMN leukocytes)
Aspiration of liver abscess
➢ Brownish-yellow pus (looks like ance & consistency of anchovy paste)
Tx Metronidazole/tinidazole – symptomatic/hepatic abscess
Iodoquinol/paromomycin – asymptomatic
Prevention Avoid fecal contamination of food/water
Good personal hygiene
Purification of water supplies
X use night soil (human feces) for crops
Properly cooked vegetable
Organism Giardia lamblia
Disease Giardiasis
Morphology Protozoa (flagellate) – intestinal
Trophozoites
➢ Pear shaped
➢ 2 nuclei
➢ 4 pairs of flagella
➢ Suction disk
, Cyst
➢ Oval thick wall
➢ 4 nuclei
➢ Several internal fibers
Virulence Suction disk
MOT Fecal oral route
RF ➢ IgA deficiency
➢ Homosexual
➢ Day care center
➢ Patient in mental hospital
Life cycle During excystation in the duodenum, cyst → 2 trophozoites
Pathogenesis Trophozoites attach to gut wall (x invade)
➢ Cause inflammation of mucosa
➢ Leading to malabsorption of protein & fat
S&S Most also asymptomatic
Watery, non-bloody, foul smelling diarrhea – steatorrhea
Yellow & greasy stool
Nausea
Anorexia
Flatulence
Abdominal cramp
X fever
Dx Diarrheal/formed stool specimens
➢ Trophozoites/cyst seen respectively
ELISA Ag
PCR
String test
➢ Weighted string swallowed
➢ After reacting duodenum
➢ Trophozoites attach to string
➢ Trophozoites visualized after string withdrawal
Tx Tinidazole/metronidazole
Prevention Filtration of water (chlorination x)
Boiled/iodine treated water
X vaccine
Organism Cryptosporidium hominis/parvum (old)
Disease Cryptosporidiosis
Morphology Protozoa (sporozoan) – intestinal
Oocyts are acid fast
➢ Contain 4 crescent shaped sporozoites
MOT Fecal oral route from human/animal
Swimming in contaminated water
Autoinfection
RF ➢ IC
Life cycle Oocyte release sporozoites
➢ Become trophozoites
➢ Later form schizonts & merozoites
➢ Eventually microgametes & macrogametes form
Both unite to produce zygote
➢ Differentiate into oocyst
Pathogenesis Oocyst excyst in SI (mostly in jejunum)
➢ Trophozoites attach to gut wall (x invasion)
S&S Mostly in IC
Watery, non-bloody diarrhea
Large fluid loss → dehydration
Malnutrition
Intractable diarrhea
Complication Diarrhea is severe in IC
Dx Fecal smear
➢ Oocytes seen w Kinyoun acid fast stain
Serology Ag
PCR
Tx Self-limited in immunocompetent
Nitazoxanide – patient w/o HIV
Paromomycin - ↓diarrhea in IC
Prevention Pasteurization & filtration can remove cyst (x chlorination)
X vaccine
Organism Balantidium coli
Disease Balantidiasis
Morphology Protozoa (ciliated) – intestinal (only ciliated protozoa that cause disease in human)
Cyst w V shaped nucleus
MOT Fecal-oral route from human/pig
Pig reservoir
RF ➢ Pig farmers
Life cycle Cyst excyst in SI
Pathogenesis Trophozoites travel to LI
➢ Burrow into wall causing ulcer similar to E. histolytica
S&S Most asymptomatic
, NVD
Dysentery
Tenesmus
Dx Diarrheal/formed stool
➢ Large ciliated trophozoites w short cilia all over the body
➢ Large cyst w V shaped nucleus
X extraintestinal lesion like E. histolytica
Tx Tetracycline/doxycycline
Prevention Avoid contamination w feces
Organism Cyclospora cayetanensis
Disease Cyclosporiasis
Morphology Protozoa (coccidia) – intestinal
Epidemiology Asso w ingestion of imported fresh produce
MOT Fecal-oral route
X animal reservoir
Life cycle = coccidia
Pathogenesis Oocyst excyst in duodenum
➢ Invade mucosa
➢ Cause destruction of brush border
S&S Watery diarrhea in both IC & immunocompromised
Complication Prolonged & relapsing diarrhea in IC
Dehydration
Dx Stool sample
➢ Spherical oocyst seen in modified acid-fast stain
PCR
Tx Trimethoprim-sulfamethoxazole (TMP-SMZ)
Organism Isospora belli
Disease Isosporiasis
Morphology Protozoa (coccidia) – intestinal
MOT Fecal-oral route
Life cycle = coccidia
S&S Diarrhea most commonly in IC
➢ Chronic
➢ Profuse
➢ Watery diarrhea
Complication Dehydration
Dx Stool sample
➢ Typical oocyst found
Tx TMP-SMX
Organism Trichomonas vaginalis
Other species: -
➢ T. hominis
➢ T. tenax
Disease Trichomoniasis
Morphology Protozoa (flagellates) – urogenital (obligate parasite)
Only trophozoite (because only involve UGT)
➢ Pear-shaped
➢ Central nucleus
➢ 4 ant flagella
➢ Undulating membrane extend 2/3 of its length
Epidemiology Frequency of symptomatic disease is ↑↑ in sexually active young women
↓↓ in postmenopausal women
MOT STD
X animal reservoir
Life cycle Replicate by binary fission
Pathogenesis Affects the vagina & prostate
T. vaginalis infect the squamous & columnar epithelium
➢ Secrete cysteine protease, adhesins, lactic acid & acetic acid
➢ Disrupt the glycogen level & lower pH of vaginal fluid
S&S Asymptomatic is common (↑↑in men)
Men
Urethritis
Women
Water, foul-smelling & greenish vaginal discharge
Pruritus
Burning
Strawberry cervix seen
Dysuria & dyspareunia
Intracellular edema – chicken-like epithelium
Complication Female
Endometritis
Pyosalpingitis
Baby (if mother has infection during birth)
Organism Entamoeba histolytica
Other species include: -
➢ E. coli – 8 nuclei
➢ E. dispar
➢ E. moshkovskii
➢ E. polecki
➢ E. hartmanni
➢ E. gingivalis
Disease Amebic dysentery & liver abscess
Morphology Protozoa (amoeba) – intestinal
Mobile trophozoites – inside GIT, extraintestinal lesion & diarrheal stool
➢ Single nucleus
➢ Even lining of peripheral chromatin
➢ Prominent small central nucleolus
➢ Fine chromatin granule along border of nuclear membrane
Non-motile cyst – 4 nuclei & outside body
➢ Smaller than most other ameba
Epidemiology More common in tropics
MOT Fecal-oral route – ingestion of cyst
Anal-oral route
X animal reservoir
RF ➢ Poor hygiene
➢ Homosexual
Life cycle Cyst excystation in ileum
➢ Ameba w 4 nuclei emerge → 8 trophozoites
➢ Mature trophozoites colonize cecum & colon
Pathogenesis Trophozoites invade the colonic epithelium
➢ Secrete enzyme causing localized necrosis
➢ Little inflammation occurs
➢ As lesion reaches the muscularis layer – flask-shaped ulcer forms
Progression into submucosa
➢ Invasion of portal circulation
➢ Reach liver to cause abscess
S&S 90% asymptomatic & become carrier
Acute
Dysentery (bloody & mucus containing diarrhea)
Lower abdominal discomfort
Flatulence
Tenesmus
Chronic
Occasional diarrhea
Weight loss
Fatigue
Amebic abscess
RUQ pain
Weight loss
Fever
Tender & enlarged liver
Complication Ameboma (mistaken for adenocarcinoma)
➢ Granulomatous lesion in cecal/rectosigmoid
Lung disease
➢ R lobe abscess from liver penetrate diaphragm → lungs
Dx Diarrheal/formed stool sample
➢ Trophozoites & cyst found respectively
➢ Trophozoites can be seen moving w ingested RBC
At least 3 sample of stool
Serology Ag
PCR
Wet mount, iodine stained wet mount & fixed trichrome stained – distinguish amebic from bacillary dysentery (bacillary ↑PMN leukocytes)
Aspiration of liver abscess
➢ Brownish-yellow pus (looks like ance & consistency of anchovy paste)
Tx Metronidazole/tinidazole – symptomatic/hepatic abscess
Iodoquinol/paromomycin – asymptomatic
Prevention Avoid fecal contamination of food/water
Good personal hygiene
Purification of water supplies
X use night soil (human feces) for crops
Properly cooked vegetable
Organism Giardia lamblia
Disease Giardiasis
Morphology Protozoa (flagellate) – intestinal
Trophozoites
➢ Pear shaped
➢ 2 nuclei
➢ 4 pairs of flagella
➢ Suction disk
, Cyst
➢ Oval thick wall
➢ 4 nuclei
➢ Several internal fibers
Virulence Suction disk
MOT Fecal oral route
RF ➢ IgA deficiency
➢ Homosexual
➢ Day care center
➢ Patient in mental hospital
Life cycle During excystation in the duodenum, cyst → 2 trophozoites
Pathogenesis Trophozoites attach to gut wall (x invade)
➢ Cause inflammation of mucosa
➢ Leading to malabsorption of protein & fat
S&S Most also asymptomatic
Watery, non-bloody, foul smelling diarrhea – steatorrhea
Yellow & greasy stool
Nausea
Anorexia
Flatulence
Abdominal cramp
X fever
Dx Diarrheal/formed stool specimens
➢ Trophozoites/cyst seen respectively
ELISA Ag
PCR
String test
➢ Weighted string swallowed
➢ After reacting duodenum
➢ Trophozoites attach to string
➢ Trophozoites visualized after string withdrawal
Tx Tinidazole/metronidazole
Prevention Filtration of water (chlorination x)
Boiled/iodine treated water
X vaccine
Organism Cryptosporidium hominis/parvum (old)
Disease Cryptosporidiosis
Morphology Protozoa (sporozoan) – intestinal
Oocyts are acid fast
➢ Contain 4 crescent shaped sporozoites
MOT Fecal oral route from human/animal
Swimming in contaminated water
Autoinfection
RF ➢ IC
Life cycle Oocyte release sporozoites
➢ Become trophozoites
➢ Later form schizonts & merozoites
➢ Eventually microgametes & macrogametes form
Both unite to produce zygote
➢ Differentiate into oocyst
Pathogenesis Oocyst excyst in SI (mostly in jejunum)
➢ Trophozoites attach to gut wall (x invasion)
S&S Mostly in IC
Watery, non-bloody diarrhea
Large fluid loss → dehydration
Malnutrition
Intractable diarrhea
Complication Diarrhea is severe in IC
Dx Fecal smear
➢ Oocytes seen w Kinyoun acid fast stain
Serology Ag
PCR
Tx Self-limited in immunocompetent
Nitazoxanide – patient w/o HIV
Paromomycin - ↓diarrhea in IC
Prevention Pasteurization & filtration can remove cyst (x chlorination)
X vaccine
Organism Balantidium coli
Disease Balantidiasis
Morphology Protozoa (ciliated) – intestinal (only ciliated protozoa that cause disease in human)
Cyst w V shaped nucleus
MOT Fecal-oral route from human/pig
Pig reservoir
RF ➢ Pig farmers
Life cycle Cyst excyst in SI
Pathogenesis Trophozoites travel to LI
➢ Burrow into wall causing ulcer similar to E. histolytica
S&S Most asymptomatic
, NVD
Dysentery
Tenesmus
Dx Diarrheal/formed stool
➢ Large ciliated trophozoites w short cilia all over the body
➢ Large cyst w V shaped nucleus
X extraintestinal lesion like E. histolytica
Tx Tetracycline/doxycycline
Prevention Avoid contamination w feces
Organism Cyclospora cayetanensis
Disease Cyclosporiasis
Morphology Protozoa (coccidia) – intestinal
Epidemiology Asso w ingestion of imported fresh produce
MOT Fecal-oral route
X animal reservoir
Life cycle = coccidia
Pathogenesis Oocyst excyst in duodenum
➢ Invade mucosa
➢ Cause destruction of brush border
S&S Watery diarrhea in both IC & immunocompromised
Complication Prolonged & relapsing diarrhea in IC
Dehydration
Dx Stool sample
➢ Spherical oocyst seen in modified acid-fast stain
PCR
Tx Trimethoprim-sulfamethoxazole (TMP-SMZ)
Organism Isospora belli
Disease Isosporiasis
Morphology Protozoa (coccidia) – intestinal
MOT Fecal-oral route
Life cycle = coccidia
S&S Diarrhea most commonly in IC
➢ Chronic
➢ Profuse
➢ Watery diarrhea
Complication Dehydration
Dx Stool sample
➢ Typical oocyst found
Tx TMP-SMX
Organism Trichomonas vaginalis
Other species: -
➢ T. hominis
➢ T. tenax
Disease Trichomoniasis
Morphology Protozoa (flagellates) – urogenital (obligate parasite)
Only trophozoite (because only involve UGT)
➢ Pear-shaped
➢ Central nucleus
➢ 4 ant flagella
➢ Undulating membrane extend 2/3 of its length
Epidemiology Frequency of symptomatic disease is ↑↑ in sexually active young women
↓↓ in postmenopausal women
MOT STD
X animal reservoir
Life cycle Replicate by binary fission
Pathogenesis Affects the vagina & prostate
T. vaginalis infect the squamous & columnar epithelium
➢ Secrete cysteine protease, adhesins, lactic acid & acetic acid
➢ Disrupt the glycogen level & lower pH of vaginal fluid
S&S Asymptomatic is common (↑↑in men)
Men
Urethritis
Women
Water, foul-smelling & greenish vaginal discharge
Pruritus
Burning
Strawberry cervix seen
Dysuria & dyspareunia
Intracellular edema – chicken-like epithelium
Complication Female
Endometritis
Pyosalpingitis
Baby (if mother has infection during birth)
