Protozoans of Medical Importance

Entamoeba histolytica - disease and mode of transmission

Disease: amoebiasis (amoebic dysentery)

Mode of transmission:

• fecal-oral route (ingesting food/water contaminated with feces)

• Ingesting cysts from contaminated food/water (cysts can be found in feces of an infected human)

Symptoms:

• bloody diarrhea (cyst bypasses stomach acid, hatches in intestines-exycstation, becomes trophozoite and feeds on intestinal lining, causing ulcerations)

• Vomiting

• Nausea

Morphology

• cyst: “bullseye” nucleus.

• Up to 4 nuclei in a single, perfectly circular cyst

Mnemonic: ENT = enteric (affects the gut)

Enteamboea histolytica

Giardia lamblia- disease and mode of transmission

Disease: Giardiasis

• also known as  "Backpacker's diarrhea" or "Beaver fever".

Mode of transmission:

• Drinking contaminated water

Symptoms:

• Watery diarrhea (no blood. Parasite doesn’t penetrate intestine)

• Greasy stool, foul smelling

Morphology:

• Pear shaped

• “owl face” nuclei: Looks like 2 eyes staring at you

• 4 flagella sticking out

Mnemonic: Giardia starts w/ G for Gut

• Go traveling you get Giardia (drinking contaminated water in the wilderness where beavers might’ve pooped and released cysts)

Giardia lamblia

Mnemonic: Giardia lamblia can be contracted when ur out in the wilderness drinking contaminated water and owls are found in the wilderness

Trichomonas vaginalis- disease and mode of transmission

Disease: trichomoniasis

Mode of transmission: sexually transmitted (Sexual intercourse)

Symptoms:

• Females: purulent discharge, dyspareunia (pain during sex), dysuria. vulvar irritation

• Males: affects male urethra and prostate

  • Inflammation of urethra, epididymis, prostate

Morphology

• four anterior flagella

• One posterior flagella along the outer membrane of the undulating membrane

• Large nucleus located at the wider, anterior end (towards flagella)

Mnemonic: you MONkey around and have irresponsible seggs = STI of trichomonas

Tricho = hair so these organisms have hair like structures sticking out

Trichomonas vaginalis

Trypanosoma brucei - disease and mode of transmission

Disease: African sleeping sickness (trypanosomiasis)

Mode of transmission: tsetse fly

• bites human and injects trypanosoma in its active (trophozoite) stage

• While biting, it injects trypomastigotes (the infective stage of Trypanosoma) into your skin

Infection occurs in 2 stages:

1. Hemolymphatic stage

   • Trypanosomes first enter lymph and then blood

2. Meningoencephalitis stage

   • happens when trypanosomes infect CNS

   • Deprive brain of glucose = coma (eternal “sleep”)

Mnemonic: “African Try to BRUise your sleep”

• to remember T.brucei causes African sleeping sickness

Morphology:

• Wiggly shaped

• Small Kinetoplast located at posterior end (behind/posterior to the nucleus)

• Often observed in blood smears

3 subspecies of T.brucei

1. Trypanosoma brucei gambiense

   • causes chronic African trypanosomiasis

   • “West African sleeping sickness”

2. Trypanosoma brucei rhodesiense

   • causes acute (rapid) African trypanosomiasis

   • “East African sleeping sickness”

   • Mnemonic: East is on the Right so it causes Rapid African trypanosomiasis

3. Trypanosoma brucei brucei

   • parasite primarily of cattle and occasionally other animals

   • Under normal. Conditions doesnt infect humans

Trypanosoma brucei

Trypanosoma cruzi- disease and mode of transmission

disease: chagas disease

Mode of transmission: “kissing bug”

• punctures thin skin (Eg: lip, eyelid) of individual

• When it defecates, its feces contains the parasite, which could enter the wound of the host

Balantidium coli- disease and mode of transmission

disease: balantidiasis

Mode of transmission: fecal-oral route

• ingesting poop contaminated food/water

Symptoms

• diarrhea

Morphology

• trophozoite contains cilia (Coli = Cilia)

• Kidney/B shaped nucleus

Mnemonic: Balantidium = B shape

Balantidium coli

Right = cyst

Left = trophozoite

Plasmodium spp. - disease and mode of transmission

disease: malaria

• parasites invade liver and rbc, causing hemolysis

mode of transmission: female Anopheles mosquito

• infection: infected mosquito bites human, injects parasite into blood.

• blood —> liver cells—> red blood cells (ring stage)—> hemolysis (shizont)

morphology:

1. ring stage: looks like a ring inside the rbc

2. shizont: a multinucleated cell inside the rbc

3. gametocyte: banana/sausage shaped. seen in blood smear.

mnemonic: PLASModium = parasite in plasma (blood) causes Malaria (plasMA MAlaria)

plasmodium spp

Plasmodium species (4) and which causes most severe infections?

1. Plasmodium Malariae

2. Plasmodium Falciparum

3. Plasmodium Vivax

4. Plasmodium Ovale

Most severe infections = P.falciparum

Toxoplasma gondii- disease and identification

disease: toxoplasmosis

• congenital toxoplasmosis: Congenital (present at birth) toxoplasmosis is passed through the placenta to the fetus. Some babies won’t have any symptoms at birth, but are at high risk for developing them later on.

mode of transmission: eating undercooked meat, ingestion/inhalation of oocysts (found in cat feces)

• Cat poop can contaminate soil, water, plant material and the food we eat.

morphology:

• crescent moon shape

• tapered anterior and blunt posterior end

mnemonic: TOXic waste in cats

Toxoplasma gondii