Eukaryotic microbes & parasites - part 1

what is a parasite

an organism that lives at the expense of another organism

what is the organism that is generally harmed by a parasite

a host

what are pathogens

parasites that cause human diseases

what are the two types of relationships of parasites to host

endoparasites and ectoparasites

what are endoparasites

live within the body of the host

what are examples of endoparasites

some protozoa and worms

what are ectoparasites

live on the surface of the host

what are some examples of ectoparasites

ticks and lice

what are permanent parasites

remain in/on the host once it has invaded

what is an example of a permanent parasite

tapeworms

what are temporary parasites

feed on and then leave the host

what is an example of temporary parasites

biting insects (mosquitos - can also be vectors)

what are accidental parasites

invade an organism other than their normal host

what is an example of an accidental parasite

a tick that normally attaches to a dog, now attaching to a human

what is hyperparasitism

refers to a parasite having parasites

what is an example of hyperparasitism

mosquitos (temporary parasites) harbor the malaria parasites

what are two examples of agents of disease transmission

mechanical transmission and biological transmission

what is mechanical transmission

passive transport of pathogens on insect’s feet or body

what is an example of a mechanical transmission

housefly transmits bacteria that cause typhoid fever from contaminated feces to food

what is biological transmission

active process where pathogen lives inside vector (ex: mosquito) and transmitted to humans by bites (ex: malaria)

what is host specificity

range of hosts in which a parasite can mature

what are the different types of hosts

definitive, intermediate, and reservoir

what is a definitive host

host in which parasite reproduces sexually

what is an intermediate host

host in which parasite carries out developmental stages other than sexual reproduction

what is an example of what developmental stages an intermediate host can carry out

asexual reproduction

what is a reservoir host

infected organisms that make the parasite available for transmission (transfer) to other hosts

what are the three parasitic mechanisms for evading host immune responses

1. encystment

2. change surface antigens

3. invade host cell and hide

what is encystment

formation of a protective outer covering

what are the purposes for encystment

1. protection from adverse environmental conditions

2. provides site for cell division and internal reorganization

3. help attach to host

4. can survive transmission between different hosts

what is an antigen

a molecule that elicits the host’s immune system to attack it

what is an antibody

a molecule made by immune system that recognizes pathogen antigens and attacks them

what can change their surface antigens

some parasites

how does changing the surface antigens allow parasites to evade the host’s immune responses 

some parasites can change surface antigens faster than the host’s immune system can make new antibodies to them

what tends to happen as a result of parasites changing their surface antigens

able to trick the host’s immune system into making antibodies that don’t recognize parasite surface antigens

how does invading the host cell allow parasites to evade the host’s immune responses

a way to “hide” from the immune system because it won’t attack its own cells

why wouldn’t the parasite just kill its host?

• would lose its own supply of nutrition

• successful parasites evolve to persist in the host without causing rapid death

what do most parasitic organisms require more of to complete their life cycle

more than one host

what can be dangerous when transferring between hosts

could die from dessication, predators, etc. → likelihood of not survivng transfer is high

what is the parasites way of enhancing survival with transfering between hosts

reproductive strategy: produce large numbers of infective progeny

what do protozoans use for producing large numbers of infective progeny

schizogony

what is schizogony

multiple fission (mitotic events) to produce many infective cells

what is an example of schizogony

worms produce large number of eggs

what can be different for some worms when producing large numbers of infective progeny

hermaphroditic

what is hermaphroditic

have both male and female reproductive organs in the same organism

what do parasites steal from host in terms of nutrition

steal already digested nutrients

what do parasites cause damage to in terms of nutrition

intestinal tract

what do parasites lead to in terms of nutrition

severe malnutrition

what are some types of trauma to host cell tissues caused by parasites

• open sores on the skin

• destroy tissue and organ cells

• clog and damage blood vessels, hemorrhaging

what can parasites trigger in the host’s in terms of immune system

trigger severe immune responses → if not invading, will lead to severe inflammatory reactions

what can mosquitos transmit to dogs

roundworms

what are the four classes of parasites

1. protists

2. fungi

3. helminths

4. arthropods

what are characteristics of protista

• primarily unicellular

• eukaryotic

• diverse morphologies

• size range: 5 mcm - 5mm

what does protista decompose

dead organic matter → recycle and used by other organisms

protists are food for what kind of consumers

higher-level consumers

some of what from protista reaches humans

energy

what do some protista have that are made of calcium carbonate, and what is it typically used for

shells, limestone used for building

how can protista be classified

based on kingdom of macroscopic organisms they most resemble

what are the three classifications based on kingdom of macroscopic organisms for protista

1. plant-like

2. fungus-like

3. animal-like

what are examples of plant-like protista

euglenoids, diatoms, dinoflagellates - algae

what are some examples of fungus-like protista

water molds, slime molds

what are some examples of animal-like protista

mastigophora, amebozoa, apicomplexan

what type of protista have several that exhibit bioluminescence

plant-like protista : dinoflagellates (algae)

what do dinoflagellates (known as plankton) cause?

red tides: alexandrium dinoflagellates

what do alexandrium dinoflagellates produce and what does it cause, in what?

neurotoxins called saxitoxins → causes paralytic shellfish poisoning (PSP) in oyster and clams

what does saxitoxins harm and what does it not harm

not harming shellfish, but kill fish and harm humans

general properties of animal-like protista

• heterotrophic

• most are unicellular

• the majority are free-living

• habitat: watery environments

which types of the animal-like protista are known to cause human disease

parasitic

are majority of the free-living animal-like protista parasitic?

no, some are commensals - one gets benefit, the other goes unharmed 

most human diseases are mainly from where

water - waterborne

what is formed by animal-like protista in response to adverse environmental conditions

cysts

what are the sub-classifications of animal-like protista

1. mastigophorans

2. amebozoa

3. apicomplexans

4. ciliates

which sub-classification of animal-like protista moves by means of flagella

mastigophorans

which sub-classification of animal-like protista was formerly called sarcodines

amebozoa

which sub-classification of animal-like protista move by means of pseudopods

amebozoa

which sub-classification of animal-like protista are also known as sporozoa

apicomplexans

which sub-classification of animal-like protista are generally not considered to be motile

apicomplexans

which sub-classification of animal-like protista move by means of cilia

ciliates

which sub-classification of animal-like protista is the largest

ciliates

which sub-classification of animal-like protista live as endosymbionts of animal digestive tracts

mastigophorans

what is trichonympha

helps termites digest cellulose

which sub-classification of animal-like protista parasitize humans

mastigophorans

what are some examples of mastigophorans that parasitize humans

• trypanosoma

• leishmania

• gairdia intestinalis

• trichomonas vaginalis

what is a specific example of a mastigophoran that can parasitize humans and cause african sleeping sickness

trypanosoma brucei

how is trypanosoma brucei diagnosed

blood smear

what is the definitive host in trypanosoma brucei

humans

what is the immediate host in trypanosoma brucei

tsetse fly / transmission by the tsetse fly

which sub-class of mastigophorans causes giardiasis and what is it

giardia intestinalis - causes diarrhea disease

how is giardia intestinalis transmitted

contaminated water

what part of the body does giardia intestinalis infect

small intestines

how is giardia intestinalis excreted

as a cyst in feces

how is giardia intestinalis diagnosed

• identification of cysts in feces

• antigen test

• string test

what are the mastigophorans that are pathogenic flagellates

• giardia intestinalis

• trichomonas vaginalis

• trypanosoma brucei

• leishmania sp.

what can giardia intestinalis cause

backpackers disease, cyst stage

what can trichomonas vaginalis cause

STD, does not have to be in cyst stage, undulating membrane

what does trypanosoma brucei cause

african sleeping sickness

what does leishmania sp. cause

skin and internal (systemic) disease, spread by and fly

which sub-class of animal-like protists are also known as ameobas

amebozoa

what do amebozoa use for motility

pseudopods (cytoplasmic projections)

what do amebozoa use their pseudopods for other than motility

to get food

what is a food vacuole and by which sub-class of animal-like protista is it used by

formed when a pseudopod engulfs food | amebozoa