Parasitology: Protozoa

protist

single celled eukaryote

Protozoa

“animal-like” protists

Groups of Protozoa

1. flagellates

2. amoebas

3. Phylum Apicomplexa

4. Phylum Microspora

5. Phylum Myxozoa

6. Phylum Ciliophora

Flagellates

protist that has at least one flagellum

Amoebas

protists that have pseudopodia

Phylum Apicomplexa

-all parasites

protists that have an apical complex

Phylum Microsporta

protists with fungi similarities

Phylum Myxozoa

protists similar to Cnidarians (jellies)

Phylum Ciliophora

protists with cilia

Pseudopoda

“fake feet” of Amoebas used for locomotion and catching prey

Endosome

nucleoulus

seen well in Entamoeba histolytica

Ectoplasm

gel-like firm liquid of the pseudopods

Endoplasm

sol-fluid-like liquid of the pseudopods

Basal body

anchors the flagellum in the cytoplasm

kinetoplast

giant mitochondrion

~characteristic of Trypanosoma

encystment

trophozoite —> cyst

excystation

cyst —> trophozoite

cyst

resistant phase of some protists, passed via host feces; infective stage

trophozoite

feeding phase of protists, motile, can undergo replication

hemoflagellate

flagellates that live in the blood

Amastigote

intracellular body form; in vertebrate host; no free flagellum

~Trypanosoma cruzi

promastigote

body form found in vector gut or salivary glands; short free flagellum
~Trypanosoma

Epimastigote

found in vector gut or salivary glands

~Trypanosoma brucei

trypomastigote

long undulating membrane body form; found in vertebrate host bloodstream; also found as the infective/metacyclic form in invertebrate host

Trypanosoma brucei disease common name

African Sleeping Sickness

Trypanosoma brucei subspecies

T.b.brucei; T.b.rhodesiense; T.b.gambiense

Trypanosoma brucei transmission

via vector: Glossina spp Tsetse fly

Trypanosoma brucei definitive host

mammals

T.b.brucei: cattle

T.b.rhodesiense: humans

T.b.gambiense: humans

Trypanosoma brucei intermediate host

Tsetse fly (Glossina spp)- also called vector

Trypanosoma brucei brucei

causes Nagana in grazing animals (malnourishment)

Trypanosoma brucei rhodesiense

fatal/acute form to humans;

Trypanosoma brucei rhodesiense location

S & E Africa

Trypanosoma brucei gambiense location

Central & W Africa

What trypanosome causes the acute form of the disease?

Trypanosoma brucei rhodesciense

T.b.gambiense reserviour host

pigs

T.b.rhodesiense zoonotic host

ungulates

Symptoms of T.b.gambiense

chronic version. 1st stage: headache, fever 2nd stage: sleeping sickness (when it has passed the blood brain barrier)

deaths are due to malnutrition or falling injuries in the sleeping stage

Trypanosoma brucei reproduction

asexual: binary fission

Where does Trypanosoma brucei reproduce?

in the blood fluids in the mammal host & in the Tsetse fly midgut

Body forms of Trypanosoma brucei

trypomastigote & epimastigote

Infective stage of Trypanosoma brucei, location & body form

in Tsetse fly as metacyclic trypamastigotes

medicine for African Sleeping Sickness

Suramin: Antimony compound that interrupts the mitochondria

How does Trypanosoma brucei evade the human immune system?

Antigenic variation/VATS-virulent antigenic types. The ability to change the chemical composition of its surface coat

Trypanosoma cruzi disease name

Chagas Disease

Trypanosoma brucei vector

kissing/assassin bug

Chagas disease location (primarily)

Brazil

diagnosis for Chagas Disease

xenodiagnosis- clean kissing bug in a container w/ ability to drink host blood, then dissected to find extracellular Trypanosoma cruzi (it’s intracellular in the human! hard to find!)

Where in the Tsetse fly does the Trypanosoma brucei mature?

Midgut (then goes to salivatory glands)

Where in the kissing bug does the Trypanosoma cruzi mature?

hindgut (then out via feces)

Lifecycle of Trypanosoma brucei starting at transmission to human

1. transmission of trypomastigotes to human via Tsetse fly bite into human blood

2. Binary fission within the blood stream

3. transmission to Tsetse fly via bug blood meal

4. in midgut, multiply by binary fission

5. transform into epimastigote and move to the salivatory glands

6. binary fission and transform to matacyclic trypomastigotes

7. transmitted to new human host via blood meal from salivatory glands into host blood

Life cycle of Trypanosoma cruzi starting with transmission to vector

1. taken up by female kissing bug blood meal in trypomastigote form

2. multiply by binary fission in hindgut

3. While kissing bug takes a new bloodmeal, it defecates, passing the trypanosome via fecal matter

4. introduced to human host when fecal matter is introduced to host via getting into a wound or into the eyes (rubbing eyes)

5. In the bloodstream, trypanosome invades cells (macrophages)

6. transform into amastigotes (intracellular!)

7. multiply via binary fission inside of the cell

8. bust out of the cell and form into trypomastigotes in the bloodstream

9. taken up via blood meal by kissing bug

Does Trypanosoma cruzi have VATs?

Nope! They don’t need the, they evade the immune system by becoming intracellular amastigotes

How does Trypanosoma cruzi evade the immune system?

it is intracellular

Acute Symptoms of Trypanosoma cruzi

Romana’s sign (swollen, infected eye) & cardiomegaly (enlarged heart-heart failure)

Romana’s Sign

symptom of acute Chagas Disease: swollen & infected eye

Symptoms of Chronic Chagas Disease

Megacolon & Megaesophagus

Acute form of chagas disease affect who?

mostly children

chronic form of Chagas disease affects who?

mostly adults (Darwin thought to have had this)

How can you diagnose African Sleeping Sickness vs Chagas?

• location of sickness (Africa or S. America)

• blood smear: are they completely extracellular trypomastigotes or are there a majority of intracellular amastigotes

• patient symptoms (sleepy or heart/colon/esophagus issues?)

What protists are hemoflagellates?

Trypanosoma brucei, Trypanosoma cruzi, Leishmania

Winterbottom’s sign

swollen lymph in the back of the neck when one is infected with Trypanosoma brucei rhodesiense

Xenodiagnosis

diagnosis for Trypanosoma cruzi where a clean kissing bug is allowed to blood-feed on the patient, allowing for dissection of kissing bug to see trypomastigote form of the parasite (intracellular in human is hard to diagnose)

Trypanosoma cruzi vector

kissing/assassin bug

Leishmania vector

sandfly

Leishmania body forms

amastigote in human, promastigote in sandfly

Leishmania types

1. Visceral

2. Cutaneous

3. Mucocutaneous

Visceral leshmaniasis

“Kala-azar” “Dum-Dum-fever” fatal version, causes enlarged spleen & liver, anemia, fever & weight-loss

Visceral leishmaniasis locations

India, Sudan, Brazil

Cutaneous leishmaniasis

“Rose of Jericho” “Oriental Sore” “Baghdad boil”

most common form, causes skin lesions/ulcers where the kissing bug bit the human

Cutaneous leishmaniasis locations

Old World, Mediterranean & Middle East

Mucocutaneous leishmaniasis

“Uta” “Espundia” “Chiclero ulcer”

destruction of cartilage tissues and mucous membranes (nose, ears, mouth, etc)

Mucocutaneous leishmaniasis location

New World- Yucatan to Argentina

What cells do Leishmania infect

macrophages

Leishmania reproduction

binary fission

Leishmania reservoir host

dog

Metacyclic

infective stage to the definitive host

Definitive host of Leishmania

human

intermediate host of Leishmania

sandfly

What host is Leishmania intracellular?

human

Diagnosis of Leishmania

Giemsa stained serum and light microscopy

Dermal leishmanoid

insufficient treatment of visceral leishmaniasis that causes bumpy sores all over (but can be fixed after treatment completed)

Giardia morphology

2 nuclei, 4 flagella, no mitochondria, ventral disk

Giardia ventral disk

used to attach to host intestinal microvilli

How is Giardia transmitted?

Encysts in the human intestines and is passed through the feces where it can contaminate food/water and be consumed by the next host

Route of infection for Giardia

oral-fecal

Route of infection for Trypanosoma brucei

vector blood meal (Tsetse fly)

Route of infection for Trypanosoma cruzi

vector fecal matter (kissing bug)

Route of infection for Leishmania

vector blood meal (sandfly)

Route of infection for Trichomonads

STD-direct transmission

Route of infection for Histomonas meleagridis

vector (nematode Heterakis)

Route of infection for Entamoeba histolytica

oral-fecal

Route of infection for Naegleria fowleri

contaminated freshwater forced into the human nose (usually in hotsprings, netti pots)

Route of infection for Acanthamoeba

contaminated solution placed into eyes (home-made contact solution)

Route of infection for Toxoplasma gondii

to feline: by consumption of raw mouse

to human/mouse: oral: oocysts passed via cat feces and mature in 24+ hrs, mature oocysts taken up orally (can pass lightly through air)

Route of infection for Plasmodium

vector blood meal: Anopheles mosquito

Route of infection for Babesia

vector blood meal (tick) to human. Transovarian between ticks (mom—> offspring)

Route of infection for Balantidium coli

oral-fecal

Why does Giardia form a cyst?

protection from external environment (between hosts)

Aspen 1964 outbreak

Giardia in old sewer pipes that leaked into drinking water

Giardia zoonotic host

beavers possibly