Lecture 27 Flashcards
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what is it called when one member(what is this) lives in or on another organism(what is this) at the expense of that organism?
parasitism
parasite; host
what is symbiosis?
living together in which any plant, animal or protist/helminth, is intimately associated with another organism of a different species, and these members are symbionts
parasitology is a type of?
symbiosis
is a fetus a parasite?
no, because they are the same species
this means traveling together?
phoresis
in phoresis, this smaller organism is carried mechanically by the host.
Example?
Phoront
bacteria, fungus, mites, leech
this is a term used when one symbiont(what is this called) benefits and the other animal is neither helped not harmed?
commensalism; commensal
close inspections of commensalism can reveal these two types of relationships? where typically
mutualistic or parasitic
Entamoeba gingivalis
the study of the relationship between a parasite and its host and is the topic for this portion of this course.
PARASITOLOGY
what are the parasitic relationships? (three of them)
temporary, facultative, or obligatory
Each member,(name this), depends upon the other; obligatory or facultative. Many examples in nature. For instance, flagellates produce cellulase in gut of termites; ciliates in ruminants and algae and fungus forming a lichen.
mutualism; mutualist
when one member, (name this), benefits and a smaller organism (name this) is harmed; usually eaten?
predation
predator; prey
this relationship is not usually considered a type of symbiosis, but it technically falls under definition?
preditor/prey
where one member, (name this), lives in or on another organism, (name this), at the expense of that organism. Host is generally not killed
parasitism
parasite; prey
this type of parasitism lives on the surface of the host?
examples?
ectoparasite; animals are infested not infected
ticks, fleas, lice
this type of parasitism lives within the host?
examples?
endoparasite; animals are infected
roundworms, tapeworms in the gut
this type of parasite lives within the parasite
examples?
hyperparasite
malaria parasites within the gut of the mosquito vector; tapeworm larvae within fleas.
parasites entering an abnormal host from a non-human animal may kill their host resulting in their own death
zoonoses
oocysts of malaria along the gut of infected mosquitos are _____ within an _____. Mosquitos are considered _____.
endoparasites; ectoparasites
vectors
a parasite of a parasite
hyperparasite
Anopheles mosquito
Plasmodium oocysts on midgut
this is the term used for transmitting parasites from host to host?
vector
organisms that transmit parasites (mosquitoes infected with malaria)
biological vector
nonliving transmitters of parasite stages (bed clothing containing lice or a spoon containing pinworm eggs/larvae.) fomite considered this
mechanical vector
the host in which parasite reaches sexual maturity and reproduces
example
definitive host
Ascaris lumbricoides
are involved with some development but the parasite does not reach sexual maturity; often asexual stages or larval stages.
example
intermediate host
Plasmodium falciparum which causes Malaria. Plasmodium undergoes its sexual stages in the mosquito, making humans the intermediate host
hosts where the parasite continues to live and is infective to next host but no parasite development takes place.
Certain roundworms can be accidentally acquired by man and migrate through the tissues without further development.
example
Paratenic hosts
Baylisascaris procyonis
larva in human brain
non-human animals that serve as sources of infection to humans
Fish infected with metacercarial stages of the trematode Clonorchis sinensis. develop within the musculature of a in variety of fish second intermediate hosts. Man acquires the infection from eating raw fish containing parasites.
reservoir hosts
what are the typical characteristics of parasites?
high reproductive potential
unique morphological or physiological specializations
Reproduction by development of an unfertilized usually female gamete that occurs especially among lower plants and invertebrate animals
parthenogenesis
what is the high reproductive potential of parasites?
multiple fission in protozoa hermaphrodism, trematodes parthenogenesis, strongyloides strobilation, tapeworms high ova/larval output, many worms
what are the unique morphological specializations?
loss of digestive tract (tapeworms)
loss of wings (fleas, lice)
loss of many sensory structures (nematodes)
development of tegument
special holdfast organs (hooks, suckers)
anti-coagulants (leeches, hookworms, mosquitos)
unique features of parasites?
- Often special site specificity
- Usually, but not always, non-lethal to host
- Generally more numerous than hosts
- Generally much smaller than host (if larger, then termed a predator)
- Often have evolved methods of evading host immune system
Pathology due to parasite infection is variable, three ways?
physical trauma
nutritional diversion
toxins/excretory products/immune complexes
blood loss
so pathology due to parasite infection is variable, one of them is physical trauma, how so?
migration of nematodes
ulceration of intestinal wall and liver by cysteine proteases of Entamoeba histolytic
displacement of tissue or structures by hyatids
protease digestion of epithelial cells by trichomonas vaginalis
ulceration due to insertion of hooks, spines into intestinal wall
how does pathology due to nutritional diversion affect the body?
giardiasis results in diarrhea and malabsorption;
Diphyllobothrium absorbs vitamin B12
how does pathology due to toxins, excretion, and ICs affect the body?
they can be absorbed
RBC lysis
fibrosis and inflammation
how can parasites be transmitted?
ingestion, vectors, direct penetration
identify parasites?
- Treatment.
- Understanding epidemiology
- Implementation of control measures.
- Fundamental research.
what are the traditional methods for diagnosing parasites and parasitic infections?
fecal specimen collection
Collection of material other than fecal
Blood films/smears
problems with diagnosis problems?
- Some parasites morphologically indistinguishable.
- Parasites hidden in host tissue.
- Low sensitivity.
traditional diagnosis for chagas’ disease?
xenodiagnosis
what are the three major methods for molecular testing?
biochemical(first generation)- isoenzymes e.g. Chagas’.
immunological(antibodies)- Ex. CATT for sleeping sickness; kits for Chagas’ & malaria; Westerns for cestodes.
nucleic acid-Ex. PCR kit for Chagas’; PCR for protozoans.
what are some bimolecular tests?
isoenzyme patterns, some separated by SDS-Page
antibody based diagnosis
what are the advantages of antibody based diagnosis?
Disadvantages?
rely on ID of specific AB
- Rapid easy field-based tests.
- Both individual & mass population screening.
- Ig subclasses – to improve specificity & sensitivity.
Disadvantages:
- Cannot distinguish past / present infections.
- Cannot distinguish morphologically similar parasites.
- Expensive to develop – significant research prior to commercialization.
what are the types of DNA based molecular diagnosis?
DNA probes
PCR
