Protists (micro)

Question 1

Parasites of veterinary importance

• Kingdom Protozoa / Protista
  – Excavates (flagellates)
  • Phylum Euglenozoa
    – Kinetoplastea (Trypanosoma)
  • Phylum Metamonada
    – Diplomonads (Giardia, Hexamita)
    – Parabasalids (Histomonas, Trichomonas)
    – Phylum Apicomplexa
    – Eimeria, Neospora etc.
    – Phylum Ciliophora (ciliates)
    – Balantidium
    – Amoebozoa
    – Entamoeba

Question 2

Protozoan vs Protist

• Protozoa is a general term for ?-celled eukaryotes, either ?-living or ?, which feed on ? matter
• A protist is any eukaryotic organism that has cells with nuclei and is not an ?, ? or ?. So includes ?, slime molds and dinoflagellates
• Neither form a natural group
• Protozoa “first and animal-like” implies a kinship with ? (metazoans), so the use of the term protozoa is discouraged by many
• For this reason, the terms “protist”, is now typically preferred for the high-level classification of eukaryotic microorganisms.
  In 2005, members of the Society of ? voted to change the name of their organization to the International Society of ?.

Answer 2

Protozoan vs Protist

• Protozoa is a general term for single-celled eukaryotes, either free-living or parasites, which feed on organic matter
• A protist is any eukaryotic organism that has cells with nuclei and is not an animal, plant or fungi. So includes algae, slime molds and dinoflagellates
• Neither form a natural group
• Protozoa “first and animal-like” implies a kinship with animals (metazoans), so the use of the term protozoa is discouraged by many
• For this reason, the terms “protist”, is now typically preferred for the high-level classification of eukaryotic microorganisms.
  In 2005, members of the ** Society of protozoologists ** voted to change the name of their organization to the ** International Society of protistologists **

Question 3

Protozoa – classified by locomotion

Phylum: Euglenozoa (Excavates) major supergroup of unicellular organisms belonging to the domain Eukaryota. Include the ? (a group of flagellates, most of which are parasitic) and ?.

Amoebozoa: The amoebozoans include protists that are distinguished by possessing ?.

Answer 3

Protozoa – classified by locomotion

Phylum: Euglenozoa (Excavates) major supergroup of unicellular organisms belonging to the domain Eukaryota. Include the diplomonads (a group of flagellates, most of which are parasitic) and kinetoplasts

Amoebozoa: The amoebozoans include protists that are distinguished by possessing pseudopods.

Question 4

Stramenopiles: (Heterokonts) Algae, kelp to diatoms & Oomycetes -> Water molds, Aphanomyces etc

Unikonts: amoebozoa and opisthokonts (fungi and animals) -> Amoebozoa; fungi/microsporidia

Excavates: amitochondriate flagellates, amoeboflagellates, Euglenozoa ->
Trypanosoma & Diplomonads

Alveolates: Ciliates, apicomplexans and dinoflagellates -> Many coccidian/apicomplexan parasites. Also ciliates and some parasitic dinoflagellates

Cercozoa: amoeboids and flagellates that feed by means of filose pseudopods, includes Halposporidians -> Ascetosporea (Haplosporidians) shellfish parasites (Marteilia) Mikrocytos ?

Question 5

Infective stage of a coccidian

a * sporozoite *

Merocystis kathae

Answer 5

Question 6

Protozoa – terminology

Zoite – ? creature
* Prefixes are added to the term “zoite” to denote a portion of the life history.
* Sporozoite – ? form
* Trophozoite – form which ? and ?
* Tachyzoite – form which ? rapidly
* Bradyzoite – form which divides ?
* Merozoite – ? (can also be infective in the case of two ? being involved)

Answer 6

Protozoa – terminology

Zoite – small creature
* Prefixes are added to the term “zoite” to denote a portion of the life history.
* Sporozoite – infective form
* Trophozoite – form which feeds and grows
* Tachyzoite – form which divides rapidly
* Bradyzoite – form that divides slowly
* Merozoite – many (can also be infective in the case of two hosts being involved)

Question 7

PROTOZOA (PROTISTS): unicellular, eukaryotic ‘animals’

• Nucleus, endoplasmic reticulum, ?, a Golgi body and ?
• Anerobic or aerobic
• Absorb nutrients or have a “?-mouth”
• Feed on ?, other ?, organic matter or tissues of the ?

(some of the flagellates have lost their mitochondria so not all have mitochondria)

Protozoa may take in food by ‘ ? ’ absorbing nutrients through their cell ?; or they may feed by ?, either by engulfing particles of food with ? (as amoebae do), or taking in food through a mouth-like aperture called a ?.

Answer 7

PROTOZOA (PROTISTS): unicellular, eukaryotic ‘animals’

• Nucleus, endoplasmic reticulum, lysosome, a Golgi body and mitochondria
• Anerobic or aerobic
• Absorb nutrients or have a “pseudo-mouth”
• Feed on bacteria, other protozoa, organic matter or tissues of the host

(some of the flagellates have lost their mitochondria so not all have mitochondria)

Protozoa may take in food by ‘ osmotrophy ’ absorbing nutrients through their cell membrane; or they may feed by phagocytosis, either by engulfing particles of food with pseudopodia (as amoebae do), or taking in food through a mouth-like aperture called a cytostome.

Question 8

Protozoa – key characteristics

Many are part of the normal ?; do not cause ? (Entamoeba – commensal
intestines; ciliates in sea urchins, Cryptobia stomach lumpfish; gregarines intestinal ‘parasites’)

• Locomotion via ?, ?, gliding movements or cilia

Answer 8

Protozoa – key characteristics

Many are part of the normal microbiota; do not cause disease (Entamoeba – commensal
intestines; ciliates in sea urchins, Cryptobia stomach lumpfish; gregarines intestinal ‘parasites’)

• Locomotion via pseudopods, flagella, gliding movements or cilia (characterised by these as well (flagella - complicated))

Question 9

• Asexual reproduction = ? exposure = significant damage
• Host(s)
  – ?-specific or ?-spectrum
  – Zoonotic or non-host specific ( ? )
• Chronic infections; immunity ( ? )
• Many form ? (in the environment or in a host). (Sarcocystis in muscles)

Answer 9

• Asexual reproduction = large exposure = significant damage
• Host(s)
  – host-specific or broad-spectrum
  – Zoonotic or non-host specific ( Toxoplasma )
• Chronic infections; immunity ( Giardia )
• Many form cysts (in the environment or in a host). (Sarcocystis in muscles)

Question 10

Protozoa – Asexual reproduction

• ? fission, * ? * / multiple fission (merogony)
• Protozoa that divide asexually have a long or short? generation time
• Schizogony (merogony)
  – ? increase in numbers
  – Destruction of host cells in proportion to the ?
  – Stops after a fixed number of ?

Answer 10

Protozoa – Asexual reproduction

• binary fission, * budding * / multiple fission (merogony)
• Protozoa that divide asexually have a short generation time
• Schizogony (merogony)
  – exponential increase in numbers
  – Destruction of host cells in proportion to the infection
  – Stops after a fixed number of repetitions

Question 11

Protozoa – binary fission

It is the most ? form of reproduction in prokaryotic organisms and occurs in some ?-celled Eukaryotes like the ? Paramecium.

Protozoa – schizogony a.k.a merogony

• Asexual reproduction of ? characterized by multiple divisions of the nucleus and cell
• Common in many apicomplexans.
  ** Intermediate host: ? reproduction: Merocystis kathae in scallops **
• Very ?

Answer 11

Protozoa – binary fission

It is the most common form of reproduction in prokaryotic organisms and occurs in some single-celled Eukaryotes like the ciliate Paramecium.

Protozoa – schizogony a.k.a merogony

• ** Asexual reproduction of protozoans ** characterized by multiple divisions of the nucleus and cell
• Common in many apicomplexans

** Intermediate host: asexual reproduction: Merocystis kathae in scallops **
- Very pathogenic

Question 12

Protozoa – sexual reproduction

Gametogony or sporogony

• Merozoites becomes either a ? (macrogamont) and then a ? OR a Microgametocyte (microgamont) and then several ?
• A microgamete fertilizes a macrogamete forming a ** ? **; a wall forms around this and it becomes an ** ? **

Definitive host: ? reproduction: Merocystis kathae in common whelk

Answer 12

Protozoa – sexual reproduction

Gametogony or sporogony

• Merozoites becomes either a Macrogametocyte (macrogamont) and then a macrogamete OR a Microgametocyte (microgamont) and then several microgametes
• A microgamete fertilizes a macrogamete forming a ** zygote **; a wall forms around this and it becomes an ** oocyte **

Definitive host: sexual reproduction: Merocystis kathae in common whelk

Not pathogenic!!!!

Question 13

Protozoa - flagellates

SUB-PHYLUM: ‘Mastigophora’ class kinetoplastida (Excavates)

locomotion by flagella

ORDER:
Kinetoplastorida
- haemoflagellates (haemo means blood)
- parasites of the blood
- generally transmitted by biting insects

yes are the ones we went through

Diplomonadorida
Trichomonadorida (YES)
- flagellates
- predominantly of the intestines

PROTOZOA GENERA
Kinetoplastorida: Trypanosoma cruzi (yes)

Diplomonadorida
Trichomonadorida: Giardia (YES), spironucleus, histomonas - poultry (YES), tritrichomonas

Question 14

Trypanosoma is a genus of ?, a monophyletic group of unicellular ? ? protozoa.

Trypanosomes infect a variety of hosts and cause various diseases, including the fatal human diseases ? sickness, caused by ? ?, and ? disease, caused by Trypanosoma ?.

Protozoa - flagellates - Giardia

Aztec emperor of Mexico
Montezuma’s revenge is a colloquial term for traveler’s ? contracted in Mexico.

Answer 14

Trypanosoma is a genus of Kinetoplastorida, a monophyletic group of unicellular parasitic flagellate protozoa.

Trypanosomes infect a variety of hosts and cause various diseases, including the fatal human diseases sleeping sickness, caused by Trypanosoma brucei, and Chagas disease, caused by Trypanosoma cruzi.

Protozoa - flagellates - Giardia

Aztec emperor of Mexico
Montezuma’s revenge is a colloquial term for traveler’s diarrhea contracted in Mexico.

• cyst (exogenous) -> ingested -> trophozoite usually in duodenum (endogenous - in the body)-> cyst and trophozoite defecated (endogenous) -> cyst by itself (exogenous)
• trophozoites are also passed in stool but they do not survive in the environment.
• contamination of water, food or hands/fomites with infective cysts and then orally into humans

Question 15

Protozoa – flagellates - Histomonas

• Histomoniasis/osis is a commercially important disease of ?, particularly of ? and turkeys, due to Histomonas meleagridis
• Clinical signs of Histomoniasis/osis include lethargy, yellow ?, appetite/weight ?, discoloration of the ? (blackhead) and death
• Histomonas specifically infects the ? and ?
• Histomonas is transmitted to the bird by the nematode parasite ? gallinarum, usually in the egg or in an ? containing infected eggs
• No current ?

Answer 15

Protozoa – flagellates - Histomonas

• Hi”st”omoniasis/osis is a commercially important disease of poultry, particularly of chicken and turkeys, due to Histomonas meleagridis

s= chicken; t = turkey

• Clinical signs of Histomoniasis/osis include lethargy, yellow diarrhea, appetite/weight loss, discoloration of the head (blackhead) and death
• Histomonas specifically infects the cecum and liver
• Histomonas is transmitted to the bird by the nematode parasite heterakis gallinarum, usually in the egg or in an earthworm containing infected eggs
• No current treatment

Question 16

Histomonas life cycle

Cecal worm (? gallinarum) life cycle

• deposit eggs in the ? tract
• chicken’s feces contain eggs
• eggs present in soil, feces and/or bedding
  OR
• eggs are ingested by earthworm
• Chicken ingests earthworm, soil, feces or bedding containing eggs
• eggs hatch, larvae grow into adults

Adult: H. gallinarum

TURKEY
? meleagridis
- infected H. gallinarum egg
- transport host: ?

Answer 16

Histomonas life cycle

Cecal worm (heterakis gallinarum) life cycle

• deposit eggs in the digestive tract
• chicken’s feces contain eggs
• eggs present in soil, feces and/or bedding
  OR
• eggs are ingested by earthworm
• Chicken ingests earthworm, soil, feces or bedding containing eggs
• eggs hatch, larvae grow into adults

Adult: H. gallinarum

TURKEY
histomonas meleagridis
- infected H. gallinarum egg
- transport host: earthworm

Question 17

Protozoa - ciliates

phylum CILIOPHORA: locomotion by ?
protozoa CILIOPHORA: ? sp.

Answer 17

Protozoa - ciliates

phylum CILIOPHORA: locomotion by cilia
protozoa CILIOPHORA: balantidium sp.

Question 18

Protozoa – ciliates

Balantidium coli

Balantidium coli is a ? species of ciliate (alveolate) that causes the disease ?. It is the only member of the ciliate phylum known to be ? to humans, also found in ? and other ?
* ** ? **
* ? in pigs
* Transmission of contaminated ?

Answer 18

Protozoa – ciliates

Balantidium coli

Balantidium coli is a parasitic species of ciliate (alveolate) that causes the disease balantidiasis. It is the only member of the ciliate phylum known to be parasitic to humans, also found in pigs and other mammals
* ** zoonotic **
* asymptomatic in pigs
* Transmission of contaminated water

Life cycle of Balantidium coli
pic: some trophozoites invade the wall of the colon;
the cyst is the infectious stage and is acquired by the host through ingestion of contaminated food or water.

Question 19

Protozoa – ciliates

balantidum sp., ? ? disease, sp name: ichthyophthirius multifiliis (always comes for NAVLE!),

encystment and division
- tomites in the substrate -> theront -> trophont -> tomont

Answer 19

Protozoa – ciliates

balantidum sp., WHITE SPOT disease, sp name: ichthyophthirius multifiliis (always comes for NAVLE!),

encystment and division
- tomites in the substrate -> theront -> trophont -> tomont

Question 20

Protozoa – Apicomplexa

Phylum:
- locomotion by gliding
- life cycle largely intracellular
- sexual and asexual phases occur

Order:
1. EUCOCCIDIORIDA:
- parasites of ? cells
- sexual and asexual repro occurs in ? cells
protozoa genera:
- eimeraia/Goussia, isospora, ?, cystoisospora (pigs), sarcocystis

2. PIROPLASMORIDA
   - parasites of ? cells
   - ticks as ?
   - sexual repro takes place in ?
   protozoa genera: babesia, ?
3. HAEMOSPORIDA
   - parasites of ? cells
   - biting ? as vectors
   - sexual repro occurs in insects
   protozoa genera: ?

Answer 20

Protozoa – Apicomplexa

Phylum:
- locomotion by gliding
- life cycle largely intracellular
- sexual and asexual phases occur

Order:
1. EUCOCCIDIORIDA:
- parasites of epithelial cells
- sexual and asexual repro occurs in epithelial cells
protozoa genera:
- eimeraia/Goussia, isospora, toxoplasma, cystoisospora (pigs), sarcocystis

2. P”I”ROPLASMORIDA
   - parasites of blood cells
   - ticks as vectors
   - sexual repro takes place in t”i”cks
   protozoa genera: Babesia, Theileria
3. HAEMOSPORIDA
   - parasites of blood cells
   - biting insects as vectors
   - sexual repro occurs in insects
   protozoa genera: plasmodium

Question 21

Eucoccidiorida
- ? of epithelial cells
- sexual and ? repro occurs. in epithelial cells

eimeria, toxoplasma, isospora, cryptosporidium, hepatozoon, sarcocystis, neospora, toxoplasma

• diagnostic stage for final host can be small
• ”? STAGE CAUSES DAMAGE”
• many have a cyst stage (oocyts)
• Oocyst ‘the ? feature’ * a cyst containing a ? formed by a parasitic protozoan

Answer 21

Eucoccidiorida
- parasites of epithelial cells
- sexual and asexual repro occurs. in epithelial cells

eimeria, toxoplasma, isospora, cryptosporidium, hepatozoon, sarcocystis, neospora, toxoplasma

• diagnostic stage for final host can be small
• “ASEXUAL STAGE CAUSES DAMAGE”
• many have a cyst stage (oocyts)
• Oocyst ‘the diagnostic feature’ * a cyst containing a zygote formed by a parasitic protozoan

Question 22

GOUSSIA OOCYST

? oocysts - four sporocysts each with ? sporozoites

Release of the sporozoites from the sporocysts is via a ? suture

2nd slide:
4 ? per oocyst
(2 ? per sporocyst)

Answer 22

GOUSSIA oocysts - four sporocysts each with 2 sporozoites

Release of the sporozoites from the sporocysts is via a longitudinal suture

2nd slide:
4 sporocysts per oocyst
(2 sporozoites per sporocyst)

Question 23

EIMERIA oocysts - four sporocysts each with two sporozoites

Release of the sporozoites from the sporocysts is via ? body at the apex of a ?

Epieimeria sp. ?
as eimeria but with ? development

Crystallospora sp.
Sporocysts with a regular ? appearance

Answer 23

EIMERIA oocysts - four sporocysts each with two sporozoites

Release of the sporozoites from the sporocysts is via Stieda body at the apex of a sporocyst

Epieimeria sp. ?
as eimeria but with epicellular development

Crystallospora sp.
Sporocysts with a regular crystalline appearance

Question 24

Common living (Molva molva)
Goussia ?

Swim bladder completely filled with goo

Lungfish (Cyclopterus lumpus)
- breakdown of ? in pyloric ?
- no sporulated oocysts yet seen
- 18S rDNA > 99% identity to
- Groussia ?: silver bream
- Eimeria subepithelialis:
common carp

Answer 24

Common living (Molva molva)
Goussia lumpus

Swim bladder completely filled with goo

Lungfish (Cyclopterus lumpus)
- breakdown of epithelium in pyloric caeca
- no sporulated oocysts yet seen
- 18S rDNA > 99% identity to
- Groussia balatonica: silver bream
- Eimeria subepithelialis:
common carp

Question 25

Protozoa – Apicomplexa – one host Many Eimeria and Goussia spp. sporulate ? of the host. In particular those infecting the ?. Others usually sporulate ?

Answer 25

Protozoa – Apicomplexa – one host Many Eimeria and Goussia spp. sporulate outside of the host. In particular, those infecting the intestines. Others usually sporulate endogenously.

Question 26

Protozoa – Apicomplexa- two hosts remember the next one!! for this just skim it. Sarcocystis spp. ingestion GI tract -> fertilization -> unsporulated cyst -> sporulated oocyst -> excretion -> sporocyst (exogenous) -> ingestion GI tract (exogenous) -> excystation -> intermediate host (prey) -> extra-intestinal (merogony - many) -> saroocyst -> ingestion GI tract causing eosinophilic ileitis, fever, abdominal pain, diarrhea or obstruction

Question 27

Sarcocystis neurona – horse is aberrant host IMP!!! Life cycle of Sarcocystis neurona BROAD: IH: 1. nine-banded ? 2. striped ? 3. raccoon (Sarcocyst in Skeletal Muscle) NARROW: DH: ? (thus DH is v specific but IH isn't) * Cause of equine ? ? * Only present in the ? * Infection in the ? cord and ? * Can lead to muscle ? and ? * Possible link with S. falcatula in birds

Answer 27

Sarcocystis neurona – horse is aberrant host IMP!!! Life cycle of Sarcocystis neurona BROAD: IH: 1.nine-banded Armadillo 2. striped skunk 3. raccoon (Sarcocyst in Skeletal Muscle) NARROW: DH: opossum thus DH is v specific but IH isn't (thus DH is v specific but IH isn't) * Cause of equine protozoal myeloencephalitis * Only present in the Americas * Infection in the spinal cord and brain * Can lead to muscle atrophy and ataxia * Possible link with S. falcatula in birds

Question 28

Protozoa -- Apicomplexa * ? for survival * Either ? or in the ? host Protozoa -- Apicomplexa Toxoplasma gondii is an ? intracellular, parasitic ? that causes the disease toxoplasmosis. - Can alter the behavior of the true ? host, to facilitate completion of the life-cycle i.e. predation DH: ? -> ? ? passed in feces -> oocysts in feed, water, or soil and ingested by ? (MANY) -> contaminated food and water consumed by ? (tachyzoites can also be transmitted through placenta)

Answer 28

Protozoa -- Apicomplexa * cyst for survival * Either environment or in the intermediate host Protozoa -- Apicomplexa Toxoplasma gondii is an obligate intracellular, parasitic alveolate that causes the disease toxoplasmosis. - Can alter the behavior of the true intermediate host, to facilitate completion of the life-cycle i.e. predation DH: cat -> unsporulated oocyst passed in feces -> oocysts in feed, water, or soil and ingested by IH (MANY) -> contaminated food and water OR tissue cysts ingested in infected uncooked meat consumed by humans (tachyzoites can also be transmitted through the placenta) -> this uncooked meat can also be eaten by cat thus cat consumes tissue cysts

Question 29

Apicomplexa – Toxoplasma gondii The cat is out of the bag: How parasites know their hosts thats how parasites know where they are - some sort of link to physiological change (to enter that into sexual place) cats have a high level of linoleic acid (doesn’t break down into arachidonic acid) tissue cysts in IH eg. mouse note: asexual in IH

Question 30

Protozoa -- Apicomplexa Piroplasmorida * Parasites of blood cells * Ticks as vectors * Sexual reproduction takes place in ? (DH) * Asexual reproduction in host ? (IH) Babesia Theileria TEXAS CATTLE FEVER: Babesia microti IMP!!! The Babesia microti life cycle involves two hosts, which include a ?, primarily the white- footed mouse and a ? in the genus Ixodes. Other species become infected when bitten by infected ?. *** The definitive host is the ? *** -> coming for exam!!

Answer 30

Protozoa -- Apicomplexa Piroplasmorida * Parasites of blood cells * Ticks as vectors * Sexual reproduction takes place in TICKS (DH) * Asexual reproduction in host mammals (IH) Babesia Theileria TEXAS CATTLE FEVER: Babesia microti IMP!!! The Babesia microti life cycle involves two hosts, which include a rodent, primarily the white- footed mouse and a tick in the genus Ixodes. Other species become infected when bitten by infected ticks. *** The definitive host is the tick *** -> coming for exam!! PIC life cycle: - babesiosis (or tick fever) - B. microti is agent for disease in U.S. B divergens in Europe - Transmission -> bite of tick - deer tick (ixodes scapularis) - aka black-legged tick - Nymphs bite humans in spring/early summer 2nd pic: tick takes a blood meal -> trophozoite -> merozoite -> back to trophozoite OR gamete -> tick takes a blood meal (ingests gametes) -> fertilization in gut of tick -> ookinete enters salivary gland -> sporogony -> sporozoites -> tick takes a blood meal again on human (sporozoites induced into human host)-> trophozoite (-> merozoite -> back to trophozoite) -> transmitted frm human to human via blood transfusion

Question 31

Protozoa -- Apicomplexa ? ? is a significant tick-borne disease caused by various species from the protozoan genus ?. Babesia canis ? parasite

Answer 31

Protozoa -- Apicomplexa canine babesia is a significant tick-borne disease caused by various species from the protozoan genus babesia. Babesia canis intraerythrocytic parasite pic: Piroplasmosis Babesia canis 1. sporozoites (transmitted by the tick) -> trophozoites -> 4 merozoites (binary fission) -> Asexual reproduction (merozoites = daughter cells) -> gametocytes (ingestion of RBCs containing gametes by the tick) -> the gametocytes fertilise themselves leading to the development of sporozoites in the tick -> then fertilization occurs in the intestine of tick and kinetes in the salivary. glands -> hatching of the sporozoites