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CHARACTERISTICS OF PROTOZOA
1. Unicellular
2. Chemoheterotrophs (get their energy
by breaking down organic matter).
3. Most ingest their food;
thus, they have special structures for this.
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CHARACTERISTICS OF PROTOZOA
4. The vegetative form is the
TROPHOZOA (tropho = movement; zoite = animal; they move
like an animal). Trophozoa have special organelles for movement.
5. Capable of reproduction
A. Asexual: fission, budding, or schizogony
(produces a large number of trophozoites)
B. Sexual: conjugation
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CHARACTERISTICS OF PROTOZOA
6. Some produce cysts.
These are
not tissue cysts like a human gets under their
skin; protozoa cysts are cellular.
They have a thick cell wall that allows for survival in harsh environments better than the trophozoite form.
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PROTOZOA CYSTS
Cysts are not as resistant as a
bacterial endospore.
You can kill cysts by boiling them.
They can live in the soil or water for months.
A cyst is no motile, so it is not trophozoic.
A cyst does not procure its nutrients or ingest food, but it can absorb nutrients.
It has no organelles to ingest food.
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Classification
Domain: Eukaryotes
Kingdom: Protista
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Classification
Traditional classification of protozoa phylae was based on
mode of locomotion.
MASTIGOPHORA (flagella)
CILIOPHORA (cilia)
SARCODINA (amoebas)
SPOROZOA (spore-formers)
Apicomplexa (attachment
organ)
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Modern Classification
Modern classification of protozoa is based on
how they evolved and how closely related they are
(phylogenetic taxonomy), as determined by their ribosomal RNA. The human pathogenic protozoa may be classified as follows:
METAMONADA (multiple flagella with feeding grooves)
AMOEBOZOA (amoebas)
APICOMPLEXA (attachment organ)
CILIOPHORA (cilia)
EUGLENOZOA (flagella and disc-shaped cristae in mitochondria)
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EUGLENOZOA
EUGLENOZOA (older classification = Mastigophora): has flagella and
its mitochondria have disc-shaped cristae
Organisms
Trypanosoma
Disease: Trypanosomiasis
Leishmania donovani
Disease: Leishmaniasis
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MASTIGOPHORA DISEASES
Trypanosomiasis
Leishmaniasis
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TERMS
Promastigote: has single flagella
Amastigote: has no flagella
Kinetoplast: round
mass of circular DNA
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Leishmania donovani
Domain: Eukaryota
Kingdom: Protista
Phylum: Mastigophora
Class: Kinetoplastida
Order: Trypanosomatida
Genus: Leishmania
Species: donovani
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Leishmania donovani
Disease: Leishmaniasis
Vector-borne disease transmitted by sandflies.
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Leishmania Life Cycle
Kinetoplast
It starts out as a spindle-shaped,
single flagellated cell called a promastigote (mastigote means flagella).
You can also see the nucleus and a kinetoplast (mass of circular DNA).
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Leishmania rosette
In prepared slides you can see promastigotes
align their nose in a circle, called a rosette.
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Leishmania Life Cycle
It reproduces in the gut of
a female sandfly, and migrates to her proboscis (mouth
part).
It is introduced into the human by her bite.
It then enters a macrophage and becomes intracellular.
Here, it loses its flagella and is now known as an amastigote.
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Leishmaniasis
These amastigotes multiply in various organs including the
spleen, liver, and lymph nodes.
Symptoms include lymph adenopathy,
fever, weight loss, and a decrease in all blood cells.
The treatment is almost as bad as the disease because of the side effects. It is best to catch it early.
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Leishmania Life Cycle
The female sandflies inject the infective
stage, promastigotes, during blood meals.
Macrophages phagocytize them and
they transform into amastigotes.
Other sandflies become infected during blood meals when they ingest infected macrophages.
In the sandfly's midgut, the parasites differentiate into promastigotes, which multiply and migrate to the proboscis.
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Leishmania donovani (Promastigote)
Single flagellum found in sand flies
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Leishmaniasis
Amastogotes
Amastogotes with nucleus and kinetoplast
Macrophage rupturing
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Sandfly
This looks like a mosquito, except its body
is hairy and the wings are feathery.
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Leishmaniasis
Geographic Distribution:
More than 90 percent of the world's
cases of visceral leishmaniasis are in India, Bangladesh, Nepal,
Sudan, and Brazil.
Leishmaniasis is also found in Mexico, Central America, and South America, southern Europe, Asia, the Middle East, and Africa.
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Leishmaniasis
There are three forms of Leishmaniasis:
Cutaneous
Mucocutaneus
Visceral
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Cutaneous Leishmaniasis
The disease is only at the site
of the bite.
This form is seen in Texas,
Mexico, Asia, and the Middle East (our Iraq troops are coming down with this form).
It manifests as a large, wet sore with raised edges. It looks like a volcano with weepy serum coming out of the center.
The wound is not contagious, just the sandfly bite.
Dogs can get this disease, too.
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Leishmaniasis (mucocunateous)
This is when the disease located in
the mucous membranes of the nose and mouth.
The
most gruesome photos are of this form.
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Leishmaniasis (visceral)
This is the most serious form. It
occurs especially in immunocompromised people, especially HIV patients.
The amastagotes
reproduce inside macrophages.
Only T-cells can kill infected macrophages, but HIV is a disease that infects T-cells.
This form is known as Kala Azar.
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Определите тип лейшманиоза
А
Б
В
Г
Visceral leishmaniosis
Old World skin leishmaniosis
New World
skin and mucous leishmaniosis
New World skin leishmaniosis (also damages
cartilage)
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TERMS
Mastigote = flagella
Promastigote: has single flagella
Amastigote: has no
flagella
Kinetoplast: round mass of circular DNA
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Trypanosomiasis
African Trypanosomiasis
(African Sleeping Sickness)
American Trypanosomiasis
(Chaga’s Disease)
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“African Sleeping Sickness”
Disease: African Tryptanosomiasis
Causal Agents:
Trypanosoma brucei
gambiense
Trypanosoma brucei rhodesiense
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Geographic Distribution
T. b. gambiense is found in foci
in large areas of West and Central Africa.
Humans are
the main reservoir for Trypanosoma brucei gambiense, but this species can also be found in animals.
T. b. rhodesiense is found in East and Southeast Africa.
Wild game animals are the main reservoir of T. b. rhodesiense.
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Trypanosomiasis
Trypanosomiasis has a biological vector, the tsetse (pronounced
“set-see”) fly.
Wild animals may also be a reservoir (Zooinotic
is when a disease is transmitted to animals as well as humans.)
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Trypanosomiasis
The tsetse fly bites a human and injects
the trypanomastigotes into the skin.
This causes a chanchre (pronounced
“shanker”), which is an ulcer on the skin.
Then it enters the lymphatic system.
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Trypanosomiasis
It is characterized by Winterbottom’s Sign: swelling of
the cervical lymph nodes in the head and neck
area.
CNS symptoms include a shuffling gait (like a stroke victim), slurred speech, and malaise (needing to sleep longer and longer each day).
They are also restless at night.
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Trypanosomiasis
CNS symptoms
Shuffling gait
Slurred speech
Malaise (sleeping all day)
Treatment
Melarsoprol: which
has dangerous side-effects like chemostherapy. This drug requires administration
with a substance called ethylene glycol, which will break down regular plastic tubing, so the drug must be administered with special plastic iv tubing.
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Trypanosoma brucei
Trypomastigote stages are the only form found
in patients.
Posterior kinetoplast
Centrally located nucleus
Undulating membrane
Anterior flagellum
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Trypanosoma brucei gambiense
trypomastigote
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“Chaga’s Disease”
Disease: American Tryptanosomiasis
A zoonotic disease (can infect
animals) that can be transmitted to humans by blood-sucking
bugs.
Causal Agent: Trypanosoma cruzi
This organism is a little smaller than T. bruceii and has a pronounced gametoplast.
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“Chaga’s Disease”
This disease is NOT found in Africa.
This disease is also zoonotic; it can infect animals
as well as humans.
The vector is a large bug called the “Kissing Bug”.
It is found in warm regions and crowded areas, especially in the cracks of adobe huts.
It comes out at night and crawls on a human while they sleep.
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“Chaga’s Disease”
It prefers the lips because the blood
supply is close to the surface.
It sucks the
blood there, but they don’t transmit the organism this way.
When they suck the blood, they also defecate, and the organism is in the feces.
When the human wakes up to scratch the itch, feces get into the tiny wound.
This is a fecal? blood route.
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“Chaga’s Disease”
Symptoms include fever, anorexia, swollen lymph nodes,
hepatosplenomegally (enlarged liver and spleen), and myocarditis (inflammation of
the heart), which usually causes death.
They also have megacolon (large colon) and megaesophagus (large esophagus).
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Trypanosoma cruzi
Insect vector is the “kissing” bug. It
takes a blood meal and releases trypomastigotes in its
feces near the site of the bite wound.
Trypomastigotes enter the host through the wound or through intact mucosal membranes, such as the conjunctiva.
Trypanosoma cruzi can also be transmitted through blood transfusions, organ transplantation, transplacentally, and in laboratory accidents.
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Trypanosoma cruzi
Geographic Distribution:
The Americas from the southern United
States to southern Argentina. Mostly in poor, rural areas
of Central and South America. Chronic Chagas disease is a major health problem in many Latin American countries. With increased population movements, the possibility of transmission by blood transfusion has become more substantial in the United States.
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Trypanosoma cruzi
large kinetoplast
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Trypanosoma cruzi
Triatomine bug, Trypanosoma cruzi vector, defecating on
the wound after taking a blood meal.
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Romana’s sign
Swollen eye, seen in Chagra’s disease.