RA 3 -parasitology Flashcards
What are ectoparasites?
Parasites that live on the surface of a host
What are endoparasites?
Parasites that live within a host
What are obligate parasites?
Parasites that must spend at least part of their life cycle in association with a host
What are facultative parasites?
Parasites that are capable of leading both a free and a parasitic existence
What are vectors?
Insects that transmits infectious agents from one host to the next
What are protozoa?
Unicellular euaryotic microbes
What are helminths?
Worms
What are nematodes?
Roundworms
What are cestodes?
Tapeworms
What are Trematodes?
Flukes
True or false: parasitic infections, although extremely important, make up only a small percentage of total morbidity and mortality worldwide
False- In fact, parasitic infections currently account for greater morbidity and mortality than any other class of infectious agents.
Mortality of parasitic infections in the US occur in what type of individuals?
Immunosuppressed
What is the definitive host?
A host in which the parasite reaches sexual maturity
What is an intermediate host?
a host that harbors larval or asexual stages of the parasite
What is a reservoir?
animal (definitive host) that serves to maintain the parasite’s life cycle in the environment.
In general, the more complicated an organism’s life cycle, the less likely chance of survival it has. How do organisms with complicated life cycles off set this?
Produce copious amount of eggs
What is he metabolically active, motile, “feeding stage” of a parasitic protist?
Trophozoite
What are the four main classes of protozoa and their mode of locomotion?
- Ameba- pseudopodia
- Flagellates -flagella
- Sporozoa- gliding
- Ciliates-cilia
What is the only ciliate that is known to infect humans?
Balantidium coli
Ameba, flagellates, and ciliates generally reproduce how?
Asexual binary fission
Sporozoans (and some amoebas) can also reproduce asexually by a process known as what?
Schizogony- (Multiple intracellular nuclear divisions (mitosis) that precede cytoplasmic division)
What is sporogony?
a sexual form of reproduction that entails multiple nuclear divisions (meiosis) followed by cytokinesis after zygote formation
What are cysts in relation to parasites?
Like spores in bacteria, but for parasites
How do cysts tavel from one host to the next?
Use a vector
What is the thick membrane that covers helminths?
Cuticle
What are the two classes of helminths?
Roundworms and flatworms
What type of helminth are nematodes?
Roundworms
What type of helminth are cestodes and trematodes?
Flatworms
What do cestodes have that trematodes do not?
alimentary canals
Which class of flatworms have sexes: cestodes or trematodes?
Trematodes
What are the two ways that parasites generate pathology?
Mechanical damage
Byproducts
Immune response
What is the immunologic pathology behind Schitosome eggs?
These are in the liver and cause disruptive granulomas
What are the three examples of deleterious immune responses to parasites?
Granuloma formation
Antigen mimicry
Immune complex formation
What are the five major immunological responses to parasites (similar to all pathogens)?
- Neutralize with antibody
- antibody + complement
- Opsonization
- Activation of macrophages
- CD8+ cytotoxic T cells
Elevation of what type of WBC is the hallmark of parasite infections?
Eosin
What is the primary antibody used to attack parasites?
IgE
Why are helminth infections particularly hard for the imune system to deal with? (2)
- Too large for phagocytosis
2. Cuticle prevents antibody action
How does size protect parasites from the immune system?
Too big for phagocytosis
How does anatomical location protect parasites from the immune system?
Intestines are hard for the immune system to get to
How does intracellular sequestration protect parasites from the immune system?
Hide from antibodies
How does cyst formation protect parasites from the immune system?
Form barrier to immune system
How does phago-lysosomal destruction protect parasites from the immune system?
Allows for them to live within macrophages
How does antigen masking protect parasites from the immune system?
some helminths will coat themselves with host cellular or serum proteins or lipids as a way of masking their own antigens from the immune system
How does immunosuppression by the parasites protect parasites from the immune system?
Production of immunosuppressive cytokines by parasite inhibit the immun system
How is differential toxicity achieved?
- preferential uptake of drug by the parasite
- metabolic alteration of the drug by the parasite
- differences in the susceptibility of functionally equivalent sites in the parasite and the host.
