Lecture24- parasites Flashcards
What is parasitism?
It is when an organism lives in or on a host- and the organism benefits while also harming the host
Describe the 3 types of parasitism
Ectoparasite- Lives In surface of host INFESTED (fleas, lice, ticks)
Endoparasite- Lives within the host INFECTED (roundworms/tapeworms) in gut
Hyper parasite- parasite living within a parasite ( malarial parasite in mosquito)
How are parasites usually got rid of?
Excretion
What are the 2 ways parasites can be transmitted from host- host?
1st
- Consumption of contaminated food or putting object in mouth contaminated with feces of an infected animal
- Vector
What are the 2ntypes of parasitic vectors?
Biological- transports AND is necessary for life cycle
Mechanical- used just to physically carry the parasite
What are Helminths?
Multicellular parasitic worms that can be seen with naked eye
What are Protozoa?
Informal grouping of -unicellular -Eukaryotic -Heterotrophic organisms Belonging to the Kingdom Protista
Give eg’s of non protozoic Protista that are biologically important
Algae- found in aquatic environments and are photosynthetic
Water & slime molds- Saprophyric like fungi but MOTILE
What is the size range of most Protozoa?
Small (2-1000 μm)
How do most Protozoa digest food, and what type do Cell wall do they possess?
Most Protozoa ingest food (Halozoic) [not parasites] and are heterotrophs
They LACK a cell wall
What is the typical environments that Protozoa live in?
Water
Moist soil
Inside other organisms (as parasites)
What are the 2 modes that Protozoa exist in, and which is most common?
-Most exist as Trophozoite- vegetative, reproducing form that feeds and multiplies
-Some exist as Cyst- Dormant, protective form from harsh conditions when cells come together (multinucleated)
Under favorable conditions the cysts can reproduce by Nuclear Organization & cell division
What are the common methods of asexual reproduction of Protozoa?
- Binary fission (most common)
- Schizogony (multiple fission) nucleus divides many times & cell separates into several daughter cells
- Budding buds form and daughter cell pinches off
Are Protozoa able to reproduce sexually?
Some are, during a part of their life cycle.
Fusion of haploid sex cells (only one of each chromosome pair)
What are the 3 types of locomotion that Protozoa May possess? Link them to the type of medically important Protozoa.
-pseudopods (amoeboids)
-Cilia (Ciliates)
-Flagella (Flagellates)
Some do not move (intracellular parasites)
Describe pseudopods of Amoeboids
- Used to move & engulf food
- they form when cytoplasm moves in a particular direction
- Phagocytoses organism by surrounding and engulfing it (algae, bacteria, other protists)
- Digestion occurs in food vacuole (contains hydrolytic enzymes)
Describe Entamoeba coli- commensals in small intestine
- Acquired by ingestion of food/water contaminated with human feces containing CYSTS
- Infection remains asymptomatic in healthy individuals
- Looks similar to Entamoeba Histolytica
Describe Entamoeba Histolytica
It is a pathogenic parasite that causes Amoebic DYSENTRY (infection of intestine with bleeding)
-Traphozoites that live and destroy tissues lining host’s large intestine
-May invade other organs (Extra-intestinal amoebiasis)
-Produces protective cysts that are passed in human feces
Humans infected by ingesting cyst
Describe ciliates
They are the most complex protists
Move by cilia through semi rigid outer covering (pellicle) and best in a coordinated rhythmic manner
Most ciliates are holozoic, sweep food particles to oral groove (gullet)
Digested in food vacuoles
After digestion, they are absorbed by cytoplasm
Food that is Indigestible exist via ANAL PORE
Most ciliates are NOT pathogenic
Describe Balantidium coli
Pathogenic ciliate fro humans
Causes diarrhea type infection
Macro nucleus is distinctly visible
Infection occurs by ingestion of food or contaminated Water with cysts
Describe flagellates
Move by flagellum, and some by Undulating Membrane (UM)
No, or atypical mitochondria (kinetoplast)
Many flagellates are Parhogenic
Describe 4 types of flagellates
The further away the kinetoplast is from the anterior end of flagellate, the faster it is
-Trypomastigote- fastest, kinetochore at posterior end (Very long flagella) with long UM
-Epimastigote- kinetochore at Middle of cell (long flagella) short UM
-Promastigote-kinetochore at anterior end of cell (short flagellum) no UM
Amastigote- circular cell with no pronounced flagella
Describe Giaedia lamblia
Flagellate that Causes giardiasis (severe diarrhea)
- Trophozoites have 2 nuclei at anterior end
- produces cysts, to be transmitted by contaminated water
Describe Trichomonas vaginalis
Flagellate that Infects vagina & make urinary tract
NO cyst formation, 4 free flagella, one with UM
Transmission through Sexual contact
Asymptomatic in most ppl
Describe Trypansoma brucei
Flagellate that infects humans & other animals
Causes African sleeping sickness
Transmitted when infected Tsetse fly bites
Also transmitted from animals to humans (zoonotic infection)
Contains kinetoplast
Found as trymastigote in host blood
Found as Epimastigote in vectors intestinal tract
Describe leishmania
Flagellate that infects humans, dogs, rodents
Transmitted via sand fly
Contains Kinetoplast
Amastigote in host cell
Promastigote in vectors gut
Causes Localized skin infections (cutaneous leishmaniasis)
How many plasmodium Protozoa infects humans and cause malaria and which is the most common one?
4, Plasmodium Vivaldi is most common
Describe Malarial disease and corresponding common parasite that causes it
Caused by Plasmodium Vivax
Transmitted via Female Anopheles Mosquito
Reproduces asexually in body cell, sexually in mosquito
SPOROZOITES pass from mosquito glands into blood, and enter Liver cells
In liver sporozoites develop into MEROZOITES
Divide asexually in RBC causing rupture (chills and fever)
Some Merozoites develop into TROPHOZOITE
Others develop into GAMETOCYSTS where next mosquito contracts it -> gametes-> zygote
How many humans approx die from malaria, and why is it out of control?
0.5million
Insecticide resistance by Anopheles
Anti malarial drug resistance by Plasmodium
