Parasitic Diseases- the basics Flashcards
what phylum do parasites belong to?
metazoa
what are the 3 classes of parasites?
- protozoa
- helminths
- arthropods
what are the 4 types (orders) of protozoa?
- sarcodina (amoeba)
- sporozoa (sporozoans)
- mastigophora (flagellates)
- ciliata (ciliates)
what are the 2 types (orders) or helminths?
- nematheminths (round worms)
2. plathelminths (flat worms)
what are the types of plathelminths?
- trematoda: flukes and flatworms
2. cestoda: tape worms
what are the 2 classes of arthropods?
- arachnida
2. insecta
what is the type of arachnida we are studying?
acarina: mites and ticks
what are the 3 types (orders) of insecta?
- siphonaptera: fleas
- diptera: flies and mosquitoes
- phthiraptera: lice
what 2 classes of metazoans are endoparasites?
- protozoa
2. helminths
what class of metazoans are ectoparasites?
arthropods
what is symbiosis?
any relationship where two or more species livel closely together
describe protozoans
eukaryotic and unicellular
describe helminths super broadly
worms
describe arthropods
jointed feet, animals!
what are the 3 kinds of symbiosis?
- mutualism
- commensalism
- parasitism
what is mutualism?
2 species living together, each dependent on the other for their mutual well-being and survival
what is commensalism?
two sepcies living together for the benefit of one or both, but without detriment to either party and without any metabolic dependence
what is parasitism?
two species living together where one of the pair (the parasite) is living at the expense of the other (the host)
what are the 2 types of parasitism?
- parasitiasis
2. parasitosis
what is parasitiasis?
parasite is present on or within the host and is potentially pathogenic, however the animal does not exhibit outward clinical signs of disease, or subclinical disease
what is parasitosis?
parasite is present on or within the host and does produce obvious injury or harm to the host animal
where do ectoparasites live? give 2 examples
on the body; fleas, fish-mouth worms
where do endoparasites live? give 2 examples
IN the body, worms, like heart worm
what are the 2 ways to classify parasites based on how/where they reproduce?
- extra/intracellular
2. macro/micro
describe extracellular parasites
live on or within host tissues but do not penetrate into host cells
what do extracellular parasites use to grow reproduce?
don’t use cell machinery, just use stuff within the host to grow and reproduce
describe intracellular parasites
live inside a host cell, modifying its genomic epxression to cater for their needs
where do microparasites multiply?
within their host
describe where macroparasites multiply
do not generally increase in number while they are on or within the final host; may produce eggs or larvae, but these are dispersed into the environment
what are the 4 types of parasites in terms of how they got to be parasites?
- erratic/aberrant parasites
- indicental parasites
- facultative parasites
- obligatory parasites
describe erratic/aberrant parasites, give an example
parasite in an ORGAN or location in which it does not normally live, got lost; like a lung worm in a kidney
describe incidental parasites, give an example
parasite found in a HOST in which it does not usually live; like when humans consume raw fish and get anisakis, whose lifecycle should only be in ocean
describe facultative parasites
free-living organisms that become parasitic with a specific host
describe obligatory parasites
parasites with a mandatory “parasitic” experience
why are obligatory parasites that way?
need lots of proteins and energy that they can’t get from environment, so they become parasitic
define life cycle
succession of developmental stages that includes at least a portion in a definitive host
what are the 2 types of life cycles of parasites?
- direct/homoxeneous
2. indirect/heteroxeneous
describe a direct/homoxeneous life cycle
one host (is the definitive/final host) that contain the adult form of the parasite and produces eggs bc parasites have access to high nutrition
describe an indirect/heteroxeneous life cycle
multiple hosts; still a definitice host, but now also intermediary hosts and even paratenic hosts
what are the 4 types of hosts in parasitic life cycles?
- definitive/final host
- intermediary host
- transport/paratenic host
- reservoir host
describe a definitive host
animal that harbors the adult, sexual or mature stages of the parasite
describe intermediary hosts
animals that harbor the immature, juvenile, asexual or larval stages of a parasite
describe transport/paratenic hosts
are a type of intermediary host where the parasite does not undergo and developmental changes and is instead encysted for transmission
describe reservoir hosts
vertebrate host in which a parasite or disease occurs in nature and is a source of infection for humans and domesticated animals
what kind of animals are mainly reservoir hosts?
wild animals; final or intermediary hosts that live in the wild and keep a disease going
can reservoir hosts undergo the disease caused by the parasite?
it’s possible, but these hosts will also keep the disease persistent
give an example of a definitive host
dogs in heatworm cycle
give an example of an intermediary host
mosquitoes in heartworm cycle
what are the 3 types of parasites in terms of their hosts
- homoxeneous/monoxeneous: one host
- stenoxeneous: narrow type of host
- euryxeneous: broad spectrum of hosts
give 3 examples of reservoir hosts and the diseases they keep circulating
- deer are reservoirs for lungworms in cattle
- rodents are reservoirs for leptospirosa
- . wildlife in general are reservoirs for rabies
describe the narrow type of hosts of stenoxeneous parasites
usually a type of animal, like small or large ruminants, carnivores, domesticated animals, etc.
what are the 2 ways/methods of defense against parasites?
- host immune reaction
2. parasiticides
what are the 2 apsectss of the host immune reaction against parasites?
- innate immunity: eosinophils play huge role here
2. adaptive immunity: lymphocytes
what are parasiticides?
“the antibodies of parasites” or chemical compounds used to treat specific internal and external parasites
what are the 4 types of parasiticides and what do they kill?
- antihelmintics: kill worms
- acaricides: kill mites/arachnides
- insecticides: kill insects
- antiprotozoals: kill protozoa only
what are the 7 aspects of parasites’ evasion of immunity/defense?
- sequestration
- masking or changing surface proteins
- disturbance of immunological effector mechanisms
- modulation of the host immune response
- influencing apoptosis
- arrested development and hypobiosis
- creating resistance to parasiticides
what is sequestration?
when parasites go to a place without easy immune access to hide from the immune system, like joints
describe parasites masking or changing surface proteins
make immune memory worthless, no immune recognition or adaptive immunity defense
describe parasites disturbing immunological effector mechanisms
parasites produce enzymes/chemicals to trick or inactivate the immune system
describe parasitic modulation of the host immune response
change how the immune system reacts, like stopping phagocytosis via lipid component synthesis
describe how parasites influence apoptosis
produce chemicals to cause the programmed cell death in the host, like death of eosinophils
describe arrested development/hypobiosis of parasites
parasites stop development until immune response is less intense
give an example of arrested development/hypobiosis of parasites
we find more parasites eggs in ewe feces during lambing bc the stress makes the immune system weak, we also see lost of eggs in lamb feces during weaning because the stress makes their immature immune system weak
describe the goals of host-parasite balance
we can’t focus on complete eradication of parasites, that’s impossible because all animals have parasites, the goal is to lower the parasite load
what are the 2 aspects of host-parasite balance?
- increased host susceptibility
2. increased parasite numbers
what 5 things increase host susceptibility to parasites?
- stressed, debilitated, or immunocompromised: important to keep stress low
- exposed to parasties with which they have not co-evolved with: as in transport
- not allowed to express natural behavior
- selectively bred for production traits at the expense of natural ability to resist infection
- inbred
what 5 things increase parasite numbers?
- host stocking density is increased
- parasitized animals are introduced into a previously clean area
- short-term weather patters or longer-term trends such as global warming
- surge in the population of intermediate hosts or vectors
- the parasite population becomes resistant to anti-parasitic medication
why does an increase in stocking density of the host increase parasite numbers?
a portion of the life cycle happens in nature, so more separation of hosts allows parasite eggs/larvae to die before infection
how do we deal with the act that introduce parasitied animals to clean animals causes an increase in parasite numbers?
give antiparasitics and quarantine
describe how weather and climate influence parasite numbers
more rain means more humidity which increases parasite survival; some parasites only like certain climates
how do we avoid anti-parasitic resistance?
cycle through 2-3 antiparasitics, like alternating flea meds
what does the damage in the host caused by parasites depend on?
the parasite location in the body
