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62 Cards in this Set

  • Front
  • Back

Parasitism

A type of durable intimate interspecific interaction where one species (the host) is harmed at least in some way by the other (the parasite)

Phorsey

When a guest hitches a temporary ride; "travelling together"


Inquilinism

When a guest makes a home inside a host but doesn't harm the host

Definitive Host

Parasite reaches sexualy maturity

Intermediate Host

Parasite development; not reach sexual maturity

Paratenic/Transport Host

No parasite development, but remains alive and infective

Reservoir Host

Animal with infection that can be transmitted to humans

The Four Great Parasitic Groups

1. Platyhelminthes - Monogeneans, trematodes, cestodes


2. Nematodes- Roundworms, pinworms, filarial worms


3. Arthropods- Crustacea, ticks, mites, insects


4. Protists- Amoebae, flagellates, apicomplexans

Phylum Platyhelminthes

-Triploblastic


-Bilateral Symmetry


-Flattened dorsoventrally "flat worms"


-No internal body space


-Digestive system incomplete


-Excretory system with protonephridida (flame cells)


-Most are hermaphrodites; internal fertilization



Class Turbellaria


Order


Temnocephalida


-most are free-living predators


-ectocommensals on crustaceans


-tentacles on anterior end; weak sucker on posterior end


Class Turbellaria


Order Dalyelloida

-Little to no pathology


-Many are in the gut/body cavity of echinoderm



Class Turbellaria


Order Dalyelloida


Synedsmis


-in Sea Urchins


Class Turbellaria


Order Dalyelloida


Fecampia

Class Turbellaria


Order Tricladida


Bdelloura candida

Phylum Platyhelminthes


Class Monogenea

-primarily on fishes (external)


-can be a serious threat when fish are crowded; hatcheries


-Host specific= narrow niche


-has an opisthaptor (w/ partial symmetry)


-bilateral symmetry


Monogean (notice opisthaptor)

Gyrodactylus


-from a Stickleback

Benedenia melleri


Monogean

Monogenean eggs (purple) and oncomiracidium

Term for the larval stage of a Monogenean?

Oncomiracidium


Oncomiracidium


- 1 to 2 eye spots


-posterior end = attachment organ with hooks (retained in adults)


-larvae swim until contacting a host, lose ciliated cells, then develop into adults

Undonella


-a hyperparasitic (parasite on a parasite) monogenean on parasitic copepods


-only found on hippo eyes

Sphyranura
- only found on mudpuppy gills

Sphyranura


- only found on mudpuppy gills


Polystoma integerrium


-three sets of suckers on opisthaptor


-found on the mouth, esophagus, and urinary bladder of frogs


-adapted to the life cycle of the frog

Class Trematoda


Subclass Aspidobothrea

-huge ventral sucker (opisthaptor) extending most of the length of the body


-parasite of snails and clams


-most have one host; in digestive tract


-all are parasitic


Subclass Aspidobothrea
Multicalyx

Subclass Aspidobothrea


Multicalyx

Larval stage of an Aspidobothrean?

Cotylocidium

Cotylocidium

Aspidogaster conchicola


-from Chinese Mystery Snail


-eggs hatch in molluscan host and young develop without further mitigation

Class Trematoda


Subclass Digenea

-make up 95% of trematodes


-ventral sucker (asitabulum) and oral sucker


-development occurs in 2 or more hosts


-1st = mollusc


- 2nd= vertebrate


Digenean Life Cycle

Miracidium (cilliated, free-swimming larva) enters 1st intermediate host (snail) -> sporocyst (embyos) develop asexually to become -> rediae develop further to become cercariae -> emerge from snail -> develop into metacercariae (infective to defin...

Miracidium (cilliated, free-swimming larva) enters 1st intermediate host (snail) -> sporocyst (embyos) develop asexually to become -> rediae develop further to become cercariae -> emerge from snail -> develop into metacercariae (infective to definitive host or infect another intermediate host)

Class Trematoda


Subclass Digenea


Schistosoma

-most prevalent in Africa, also in South Africa


-live as adults in blood vessels (in the mesenteric veins)


-aka blood flukes


-release about 1000 eggs/day


-disease is called schistosomiasis


-pathological sign= blood in urine


-have separate sexes


-each species is specific to a species of snail

Schistosoma mansoni


-grooves in the male body (gynecophoric canal) holds female

Prevalence

The proportion of hosts infected by a species of parasite

Intensity

the number of parasites of a species in an individual host

Mean Intensity

The mean number of individuals of a parasite species amoung infected hosts

Schistosome Life Cycle

-eggs are distributed into freshwater and when in water eggs hatch and develop into miracidium with cilia


-when finding a snail (intermediate host), miracidium penetrates the skin and make its way inside the body and develops into a mother sporocyst which then asexually reproduces more sporocysts


-daugther sporocysts migrate to snail's reproductive tissue and destroys it and stays there


-develops into cercariae that are excreted by the snail


-cercariae must then find a human host (definitive host)

Schistosoma mansoni egg with miracidium (inside)

Schistosoma cerecaria

Schistosome Control

-chemotherapy (expensive)


-vaccines


-molluscicides (kill the molluscs)


-enviro manipulations


-education


-biocontrol (less effective)


**Best way= interrupt parasite life cycle

Concomitant Immunity

If you have a few worms already, you can't be infected again while you have the worms

Generalized Digenean Life Cycle

Egg -> miracidium -> sporocyst -> redia -> cercaria -> metaceracaria -> adult

Redia (note pharynx and gut)

Metacercariae

Trophic Transmission

Parasite is transmitted to next host by a predation event

Leucochloridium in snail


-snail's tentacles become brightly colored and striped to attract predators (birds)


-no secondary host needed


-parasite reproduces in bird and bird defecates the eggs everywhere

Clinostomum marginatum Life Cycle

-Eggs defecated by birds


-miracidium penetrates snail


-asexually reproduces in snail to cercariae


-cercarae released from snail and develop into metacercariae


-metacercaria infect fish


-birds eat the fish and cycle starts over

Phylum Platyhelminthes


Class Cestoda

Tapeworms!


-absorb nutrients through surfaces


-each proglottid (segment) can reproduce


-Scolex


-attaching mouth part


-looks differant depending on development stage


-neck is the region of rapid growth of more proglottids

Proglottid

-Reproductive segments of tapeworms


-immature proglottids lack reproductive organs


-gravid (filled with eggs) proglottids release eggs and are near the end of the worm


-dropped off when eggs released

Tegument

-cestode surface


-microthrix = finger-like projections cover the surface in order to maximize surface area

Cestode Nurtient Absorption

-better than the host!


-carbohydrates are the limiting factor


-worms can only absorb monosaccarides


-host digestive rate will increase


Immature proglottid

/

Hymenoleptis


-primarily a rat tapeworm


-have 3 testes and 1 ovary in each gravid proglottid


-only takes a little bit of nutrients, not hard on host


-uninfected/infected rats have very similar intestinal absorpition rates

Ligula


-plerocercoids


-prefers the carp family


-grows very quickly in secondary host (fish)

Schistocephalus


-plerocercoids in Stickleback fish


-causes a lot of damage


-fish cannot keep up with nutrient demand so it stays in shallow water where it is easier to find food, but predation risk is higher


-birds (definitve host) eat the fish

PITT

Parasitic Increased Trophic Transimission


-metacercariae modify behavior of intermediate host so they are more likely to be consumed by the definitive host

Phylum Platyhelmintes


Class Cestoda

-body = monozoic (tapeworm whose strobila consits on one segment) or polyzoic


-Strobilation


-eggs with infective oncosphere; oncospher has hooks for crossing intestinal wall


-infected intermediate hosts eaten by definitive host


-diverse taxonomic group (scolices; reproductive arrangements, life cycle variation)

Class Cestoda


Subclass Eucestoda


Order Diphyllobothriidea (= Psuedophyllidea)

-scolex has a bothria

Hymenalypis dimenuta

-found in rats and people


-only 1 intermediate host (beetle), but its not required


-oncosphere -> cysticercoid


-scolex develops first (invaginated), and projects when consumed by definitive host


Hymenalypis nana

-dwarf tapeworm (nana)


-similar to H. dimenuta


-children are commonly infected

H. dimenuta Life Cycle

-eggs defectated by humans


-ingested by an arthropod (intermediate host)


-oncosphere hatches and penetrates intestinal wall


-cysticerci in insect ingested by rodent or human (infective stage)


-develops into an adult in definitve host

Class Cestoda


Subclass Eucestoda


Order Cyclophyllidea

-very large subclass


-important to the medical field


-Scolex has 4 suckers with a rounded tip (rostellum)



Diphyllobothrium latum


-scolex has bothria


-