COMMON PARASITES AFFECTING MAN: PROTOZOANS

Entamoeba histolytica: CHARACTERISTICS

Pseudopod-forming intestinal protozoa
Brownian Movement

What class of protozoan does Entamoeba histolytica belong to?

SARCODINA

DEFINITIVE HOST of Entamoeba histolytica

MAN

Primary MOT of Entamoeba histolytica

FECAL-ORAL

INFECTIVE STAGE

MATURE CYSTS

Describe the basic morphology of Trophozoite

• unicellular with pseudopods

• fingerlike projections for locomotion

Describe the basic morphology of cyst

• has 4 nuclei that characteristically have centrally located karyosomes and fine

• uniformly distributed peripheral chromatin

Diagnostic Stage

• Trophozoite

• Cyst

What disease is caused by Entamoeba histolytica?

Amoebiasis

• Amoebic colitis

• Extraintestinal Amoebiasis

In the disease amoebic colitis, Trophozoites reach the cecum and

penetrate the mucosa using what movement?

AMEBOID MOVEMENT

Give me the virulence factor for this protozoans

Cysteine Proteases

• tissue invasion and immune evasion by degrading extracullar matrix and host proteins

What happens to the liver when trophozoites burrow deeper into the organs

• there is amoebic liver abscess;

DIAGNOSIS

• Direct fecal oral

- Trophozoites

- Cysts

• Examination of aspirate for liver

abscess

It is a Pseudopod-forming intestinal protozoa

Entamoeba Histolytica

Giardia lamblia: CHARACTERISTICS

• flagellate intestinal protozoan

• falling leaf motility or corkscrew

What is the class of Giardia lamblia?

Mastigophara

What is the characteristic motility of Giardia lamblia?

Falling leaf motility

Describe the trophozoite form of Giardia lamblia.

Pear-shaped, two nuclei, four pairs of flagella, and a suction disk

What is the infective stage of Entamoeba histolytica and Giardia lamblia?

Mature cysts

Where does excystation of Entamoeba histolytica occur?

Small intestine (cecum)

Where does excystation of Giardia lamblia occur?

Duodenum

What disease is caused by Giardia lamblia?

Giardiasis (Traveler’s diarrhea)

What is the characteristic stool presentation in giardiasis?

Persistent, foul-smelling, non-bloody diarrhea with steatorrhea (fatty stool)

How does Giardia lamblia cause malabsorption?

Forms a mechanical barrier on the duodenum and jejunum, impairing protein and fat absorption (because of the suction disk)

What type of ulcer does Entamoeba histolytica form in the colon?

Flask-shaped ulcers

What does the aspirate from an amoebic liver abscess resemble?

Anchovy paste

What are the diagnostic methods for Giardia lamblia?

Direct fecal smear, trophozoites and cysts; String Test

What are the diagnostic methods for Entamoeba histolytica?

Direct fecal smear for trophozoites/cysts; aspirate analysis for liver abscess

What class does Balantidium coli belong to?

Ciliata

The only ciliated protozoan that causes human disease

Balantidium coli

Where does Balantidium coli inhabit in the human body?

Large intestine

What is the morphology of Balantidium coli trophozoite?

Large ciliated trophozoite

What is the morphology of Balantidium coli cyst?

Large cyst with a characteristic V-shaped nucleus

What is the definitive host of Balantidium coli?

Pigs (reservoir host); humans are accidental hosts

What is the mode of transmission of Balantidium coli?

Fecal-oral route

What is the infective stage of Balantidium coli?

Mature cyst

What are the diagnostic stages of Balantidium coli?

Trophozoite and cyst

Where does cysts undergo excystation in Balantidium coli

In the small intestine

What happens after excystation in the small intestine of the protozoan Balantidium coli?

• the hatched egg (trophozoites) goes to large intestine

• inhibit large intestine to do its main work (absorbing water and electrolytes from undigested food and turn it to feces)

• bloody diarrhea happens

• dehydration

What disease does Balantidium coli cause?

Balantidiasis / Balantidial dysentery

What enzyme does Balantidium coli secrete to aid invasion?

Hyaluronidase

Describe the type of ulcers does Balantidium coli produce?

Ulcers with rounded bases and wide necks

What are common symptoms of Balantidial dysentery?

Bloody mucoid diarrhea, abdominal pain, vomiting

What class does Trichomonas vaginalis belong to?

Mastigophora

What is unique about Trichomonas vaginalis' life stages?

Exists only as a trophozoite (no cyst stage)

Where does the Trichomonas vaginalis inhabit?

Both the GUT of males and females

Where does Trichomonas vaginalis inhabit in females?

Vaginal epithelium

Where does Trichomonas vaginalis inhabit in males?

Urethra and prostate gland

What is the optimal pH for Trichomonas vaginalis survival?

pH 5.2 to 6.4

What is the morphology of Trichomonas vaginalis trophozoite?

Pear-shaped with a free flagellum, jerky movement

What is the definitive host of Trichomonas vaginalis?

Humans

What is the mode of transmission of Trichomonas vaginalis?

Sexual intercourse

What is the infective stage of Trichomonas vaginalis?

Trophozoite

• same as the diagnostic

Describe the life cycle of Trichomonas vaginalis.

• sexually transmitted

• attach to epithelial cells in the urogenital tract

• multiply

• inflammation

What disease does Trichomonas vaginalis cause?

Trichomoniasis

What are symptoms of Trichomoniasis in females?

• green-yellowish discharge

• intense itching or burning

What condition is characterized by "Strawberry Cervix"?

Trichomoniasis (seen on speculum exam)

What are symptoms of Trichomoniasis in males?

Urethritis; can be asymptomatic

How is Trichomonas vaginalis diagnosed in females?

Microscopic exam of urine, urethral, vaginal, or cervical secretions (semen for men)