Test 3: Intro to Parasites Flashcards
Before the 1700’s, what did they think cause tooth decay?
worms
- proven due to bacteria
How are parasites relevant in oral disease?
- 2 protozoa are
If it benefits both organism and other organism?
mutalism
What is the definition of a parasite?
- when one organism lives in close association with and usually at the expense of another
- usually do not kill
- due to result of long co-evolutationary histories
Why don’t parasites kill?
- because they require the host to survive and have adapted overtime
Is TB considered to be in parasitology?
- no, only because they thought TB germs would kill although they fit the other criteria
What does parasitology usually have in common in regards to the disciplines/criteria?
medical entomology (insects)
What is the definition of a definitive host?
- where sexually mature adult parasite lives
(zygote type of protozoan)
What is the definition of intermediate host?
- supports a stage in parasite development
What is the definition of a dead-end host?
- on where the parasite does not replicate or transmit, but dies which can potentially cause more significant disease
What are protozoans?
- single-celled eukaryotes
- greek for first animals
- originally classified by type of motility: flagellates
Does sporozoa move?
No! It does NOT move
What is another word for helminths?
- worms and flukes
How are the major human infections involved in helminths spread? (the big 3)
- soil-transmitted
What are the big 3 helminths?
- giant roundworm (ascaris lumbercoides)
- whipworm (trichuris trichuria)
- hookworms (necator and ancylostoma)
Which are arguably the most common infectious agents?
helminths
Who does pinworms infect?
infect nearly all children and adults are asymptomatic
What is toxoplasma gondii?
- an intracellular protozoan
- risk of congenital transmission/ocular disease so only a problem with pregnant women
- often asymptomatic with rates at 50%
What is trichomonas vaginalis?
- often asymptomatic venereal disease
What is giardia?
- most common acute symptomatic human parasite disease
- no geographic boundaries
- commonly seen in urban and rural
What percent of humans have parasite infections?
- an estimate of 50% with 4.46 billion
How many US people were parasite positive in the stool specimen research?
- 10-33%
What are blastocysts?
algae-like protozoan
- have some common symptoms with GI problems
What are the 4 modes of parasitic infections transmission?
- ingestion
- direct skin penetration
- direct person to person
- insect bites
What is the one distinctive feature of all parasites?
- malnutrition (lose weight)
Why are many parasitic infections less acute compared to viral/bacterial diseases?
- co-evolution favors reduced host damage
What is the hygiene hypothesis have to do with parasites?
- big families and the kids have a lot less autoimmune diseases
- worms are our friends and we shouldn’t eliminate them or we will have more autoimmune disease
How are parasites transmitted?
- egg cysts/ larvae
- penetrate skin as adult parasites
- toxoplasma= congenitally
How can we reduce parasite infection?
- clean water infrastructure, sanitation
What is the tx for parasites?
- most commonly respond well to tx
- anti parasitic drugs target eukaryotic cells
- for protozoans: metronidizaole (flagyl)
- for worms: benzamidazoles
How does metronidazoles work?
- convert to an active agent by anaerobic metabolism which then causes DNA damage
- for protozoans
- not much resistance to it because it’s not specific
How does benzamidazoles work?
- interfere with nematode tubule function, killing worm movement and worms in several days
- for worms
What is the prevention for parasites?
- not many vaccines for parasites
- really just improve sanitation and hygiene and insect vector control programs
- insect nets treated with pyarthin
What should travelers consider for parasitic invention?
- wearing minimal shoes to avoid hookworms
- mosquito netting, insect repelling
- avoid swimming in fresh water
- eating food more cooked
- remain hydrated
What ribosome grouping does ciliates have?
16s
(not 18s like eukaryotes)
What ribosome grouping does ciliates have?
16s
(not 18s like eukaryotes)
What is the insect parasite worth mentioning?
head louse
- spread head-to-head
What is nightsoil fertilizer?
good fertilizer where many worm eggs live and survive in it
