Lecture B1 - Introduction to the Biology of Parasitic Protozoa Flashcards
What is parasitic protozoa?
Microscopic, one celled organisms that are parasitic in nature and can multiply in humans and cause serious disease.
What is the GPI-anchor?
Glycosyl-phosphatidyl-inositol anchor.
What helped in establishing the structure of GPI-anchors?
Variant surface glycoprotein of Trypanosome Brucei.
What is the archezoa hypothesis?
Nucleus was invented before the mitochondrion was acquired.
First eukaryotes were anaerobes.
When would the archezoa hypothesis fall?
Archezoans branch among aerobic species with mitochondria.
Mitochondrial genes on archezoan genomes.
Mitochondrion derived organelles in archezoans.
What are some unusual organelles from parasites?
Unusual mitochondria.
Highly reduced organelles often without mitDNA, hydrogenosomes and mitosomes.
Apical organelles of aplicomplexans essential for invasion of host cells.
The polar tube of microsporidia essential for invasion of host cells.
Glycosides in kinetåplastids.
Non-photosynthetic plastids in apicomplexa.
What do most apicomplexa possess?
An apicoplast which is a secondary plastid.
Name some common parasites that transmission route is via mucosal surfaces.
Toxoplasma gondi
Trichomonas vaginalis
Giardia limblia
Name some parasites that transmitted through insects.
Trypanosoma
Leishmania
What is symbiosis?
The association between organisms from different species - different types of association can be defined.
What are the three main categories of symbiosis?
Mutalism
Commensalism
Parasitism
Describe mutualism.
Both partners benefit from the interaction and they are co-dependent for thriving.
Describe commensalism.
One partner benefits from the interaction whereas the other is neither harmed nor benefitted.
Describe parasitism.
One partner relies on a host for nutrients and shelter and there is a potential cost to the host - it is as a potential pathogen causing pathologies to the host.
What are obligate symbionts?
Require a host to complete their life cycle.
What are facultative pathogens?
Don’t cause disease all the time, blurring the distinction between pathogens and commensals.
What are opportunistic pathogens?
Cause pathologies when the host is compromised - example is AIDS, patient is immunodeficient so parasite can take over.
What are 2 examples of free-living species as occasional/accidental pathogens?
Acanthamoeba spp.
Naegleria fowleri.
Extremely rare but gets in through your nose and kills within a week.
Why are the best parasites ones that don’t kill?
Because if the host is killed then they can’t propagate and die too.
This leads to long term interactions between hosts and pathogens.
What is a monoxenous parasite?
A parasite requiring a single host for completing their life cycle.
What is a herexenous parasite?
A parasite requiring two or more hosts to complete their life cycle. Intermediate host(s) required for development and the definite host required for sexual maturity.
What are human diseases caused by animal parasites called?
Zoonoses.
What is the 3 modes of transmission of parasites?
Contact transmission
Vehicle dependent
Vector transmission
Name some examples of parasites that inhabit the digestive tract.
Amoeba
Diplomonada
Parabasalia
Ciliates
Stramenopile
Apicomplexa
Microsporidia
What are some decal-oral transmission factors?
Personal hygiene (food handling, institutions, children in day care)
Developing countries (highly endemic, poor sanitation, travellers diarrhoea)
Water-borne epidemics
Zoonoses
What is the life cycle of microsporidia?
Invasion of new host cells via the polar tube
Amplification and differentiation into spores
Release of spores from infected host cells
Typically infects intestinal cells in mammals
Can invade other tissues
What are the 2 common cryptosporidium species infecting humans?
C. parvum
C. hominis
Describe toxoplasma gondi.
Has an immature host and a definitive host.
Cosmopolitan distribution.
Seropositive prevalence rates vary greatly.
Thought to generally cause being disease in immunocompetent adults.
Tissue cyst forming coccidia.
Usually doesn’t affect humans but if someone becomes immunocompromised it can cause problems.
What are some important human pathogens that are transmitted by arthropods vectors?
Plasmodium falciparum P. vivax
Trypanosome Brucei
Leishmania spp
