Introduction to Protazoa Flashcards
Is Protozoa multicellular or unicellular? What else is important about them?
Unicellular
- single celled, distinct nucleus, microscopic, with greater complexity than other unicellular forms ( bacteria)
- Each protozoa possess specialized organelles
and function as independent organism
Are most Protozoa pathogenic?
Most are free living and are not pathogenic but some co-
exist with animal hosts (parasitic protozoa)
What is the life cycle of Protozoa?
Life cycle – direct (e.g Eimeria) or indirect (e.g Sarcocystics, Trypanosoma)
What kind of reproduction is seen in Protozoa?
Asexual (e.g Giardia) or alteration of sexual and asexual lifecycle (e.g Toxoplasm
Do Protozoa gravitate to a specific host?
Varied host specificity – High (e.g Sacocystics, Eimeria) or low (e.g Cryptosporidium)
What is the pathogenicity caused by protozoa?
Pathogenicity is caused either by destruction of host cells, toxins or by changes in host immune
system
What is an important consideration for protozoa?
Important to consider zoonotic potential
What is important to remember when trying to control, diagnose, and treat protozoal infections?
- Control requires knowledge of complete lifecycle
- Diagnosis – Morphology, Serological and molecular
- Treatment may not kill all stages
What are the four groups of Protozoa of veterinary importance? What are they grouped by?
Flagellates
Amoebas
Ciliates
Apicomplexans
They are grouped based on their locomotion
What is some important characteristics of Flagellates?
- Locomotion by flagella
- Mucosoflagellates (Direct life cycle, ex: giardia)
- Haemoflagellates (Arthropod transmitted, ex: trypansoma)
What is some important characteristics of Ameobas?
Locomotion by pseudopodia
- Direct life cycles
- Ex: Naegleria fowleri, E. Histolytica
What is some important characteristics of Cillates?
Locomotion by cillia
- Direct life cycles
- Eg. balantidium coli
What is some important characteristics of Apicomplexans?
Locomotion by gliding
Coccidia:
- Direct life cycle (Ex: elmeria, crypto)
- Indirect life cycle (Ex: Toxoplasma)
Haemosporida
- Arthropod transmitted (Ex: Babesia)
What is the morphological characteristics of muscoflagellates?
- Pear shaped
- Most have direct life cycle
- e.g Giardia, Tritrichomonas spp. – direct lifecycle
- Histomonas – Indirect lifecycle ( transmitted by another
parasite)
Two stage: Cyst and Trophozite ( only stage in Trypansoma)
In Muscoflagellates, what are the key differences between Trophozoites and cysts?
Trophozoite
• Active motile form
• Vegetative form – divides by binary
fission
• Doesnot survive well in the
environment
• Only stage in Trypanosoma
Cyst
• Non-motile
• Environmentally resistant stage
• Can survive for months in wet and
cool conditions
In muscoflagellates, what is a more simple breakdown of trophozoite vs. cyst stages?
Trophozoite stage is the feeding stage of the protozoan. Cyst stage is the dormant, resistant infectious stage of the protozoan
How are hemoflagellates transmitted?
Arthropod transmitted
Where are hemoflagellates found?
Lie in blood/ tissues of animals/ humans
What are the 3 different forms of hemoflagellates and what makes them differ from one another?
- Amastigote – Mammalian intracellular form
No flagella or undulating membrane - Promastigote – Arthropod gut form
Long flagella, spindle shaped body - Trypomastigote- Mammalian blood form
Long flagella, spindle shaped body
What are apicomplexans? What are some key characteristics?
- Obligate intracellular pathogens
- Designed to get inside cells – Apical complex (organelle for invasion)
- Complex lifecycle – Direct (D) or indirect (I)
- Life cycle alternates between sexual and asexual reproduction
What are 3 types of apicomplexans?
- ) Intestinal (coccidia)
- )Systemic
- ) Blood
What kind of life cycle do intestinal apicomplexans have and what are some examples?
Direct Lifecycle (Examples: Cryptosporidium, Eimeria, Cystoisospora)
What kind of life cycle do Systemic apicomplexans have and what are some examples?
Indirect lifecycles ( Toxoplasma, Neospora, Sarcocystis)
What kind of life cycle do blood apicomplexans have and what are some examples?
Indirect- Arthropod transmitted
(Ex: Babesia, Cytauxzoon)
What are the steps to the lifecycle of intestinal coccidia?
1.) Dog is infected (sporulated oocysts of isospora enter the gut)
2.) The shell of the oocyst Sexual reproduction breaks down and (GAMETOGONY) – releases parasitic production of male and sporozoites, which female gametes and penetrate intestinal fusion, resulting in epithelial cells
fertilized zygote
- ) Asexual Reproduction (Merogony)
- ) Sexual reproduction breaks down and (GAMETOGONY) – releases parasitic production of male and sporozoites, which female gametes and penetrate intestinal fusion.
- ) Zygote is created
- )Zytoge developes into an oocyst that exits the canine host in feces
(6) the oocysts sporulate (SPOROGONY) in the environment in a few days and becomes infectious to new dogs.
What is the lifecycle of systemic coccidia (toxoplasma)?
Asexual (merogony) and sexual
(gametogony) phase in definitive hosts
- Only asexual (division, multiplication) in
Intermediate hosts - Only for toxoplasma, transmission can
occur between intermediate hosts! - For other systemic coccidia (Sarcocystis,
neospora) - transmission to definitive hosts occurs
by ingesting the cysts in the tissue of
the IH, and - transmission to IH occurs via ingestion
of sporulated oocyst!
What is the lifecycle of blood apicomplexa?
Ex: Babesia Canis
- ) Tick has blood meal from infected animal, and sporozoites remain in the salivary glands of ticks.
- ) Sexual reproduction of protazoa occurs within the tick, and tick takes bloodmeal from new host.
- ) New host is innoculated via bite.
- ) Asexual reproduction occurs within the hosts erythrocytes.
Cycle repeats.
What is a rare way blood ampicomplexans can be transmitted, other than through an arthropod vector?
Iatrogenic transmission is also possible
through blood transfusion or blood- contaminated fomites.
How can you diagnosis a protozoal infection? What does each test detect?
- ) Fecal testing- microscopy (fecal float/ smear for intestinal protozoa)
- can detect f cysts, torphozoites, oocysts in feces (quick diagnosis in clinical cases) - ) Blood testing- Direct smear, stained smear (Blood protozoa are specific on the types of blood cells they infect!)
- ) Serological/ Molecular methods
- Examination of blood/ serum for Antibody against parasites (serology)
- Examination of feces for parasite/ antigen ( active infection)
- Extracting DNA of the parasite and sequencing- High accuracy.
