Parasitic Diseases- Helminths Flashcards
what are the 3 classifications of helminths?
- trematodes: plathelminths, flatworms
- cestodes: plathelminths, tapeworms
- nematodes: nemathelminths, roundworms
give one example of trematodes that we are studying
fasciola hepatica- flukes
what kind of life cycle do flukes have?
indirect
what is special about flukes’ sexual bits?
they are hermaphrodites, do not asexually reproduce, just do both parts on their own
what kind of animal is the final host for flukes?
ruminants, like cattle, sheep, alpacas, and llamas
what is the intermediary host of flukes?
freshwater snails
what is the one health concern about flukes?
zoonotic; humans can be accidental final host and not close the cycle via ingestion of unwashed/contaminated veggies
what is the severity of a fasciola hepatica infection in sheep, alpacas, and llamas?
devastating, acute, often fatal
what is the severity of a fasciola hepatica infection in cattle?
asymptomatic infection, chronic, rarely fatal
where is fasciola hepatica most often found? why?
south US; more rainfall and ponds means more freshwater snail intermediary hosts
how do you diagnose a fasciola hepatica infection and why?
use sedimentation because the eggs don’t float due to the operculated nature of their eggs (an opening in the top)
what kind of infection does fasciola hepatica cause in cattle?
chronic, rarely fatal
what is black disease?
occurs when fasciola hepatica infection concurrent Clostridium novyi infection, common in sheep and usually fatal becuase it fucks the liver
what are the signs of a fasciola hepatica infection (mostly in small ruminants)
- anemia
- unthriftiness
- submandibular edema
- reduced milk production
what are the signs of fasciola hepatica in heavily infected cattle?
may show now clinical signs!! (HAHA trick question, keep up the studying gal)
what are the 3 aspects of control of fasciola hepatica?
- removal of flukes in affected animals with antihelminthics
- reduction of the intermediate host snail population
- prevention of livestock access to snail-infected pasture
describe the indirect life cycle of fasciola hepatica (kinda messy, Suarez didn’t describe so probs not as important as others)
unembryonated eggs are passed in feces, and they become embryonated in water, where they evolve into miracidia and hatch in the water to invade a snail host, where they change into cercariae inside the snail, which are released and encyst on freshwater plants and migrate up to the top of grass and are ingested, as flukes, by ruminants, where they undergo sexual reproduction to make eggs that enter the bile system, then the intestine, and are secreted in the liver
what 3 cestodes are we studying?
- Taenia solium
- Taenia saginata
- Taenia multiceps
describe the body of cestodes
long, segmented, and tapelike
how long are most cestodes?
a few mm to up to 20 meters
describe the sexual bits of most cestodes
hermaphroditic
what are the 3 main sections of cestodes’ bodies?
- head (scolex): has hooks (rostellium) and suckers
- neck
- strobila (proglottids)
what do the hooks on the cestode head do?
anchor to the intestinal mucosa
what do the suckers on the cestode head do?
attach to the intestinal mucosa
do cestodes have a digestive tract? what absorbs nutrients if not?
no digestive tract, head absorbs nutrients
describe the strobila of cestode bodies
segments, each is a full hermaphroditic repro unit,are excreted in feces and look like rice
describe the life cycles of cestodes
most indirect, have 2 hosts: intermediate and final
describe the severity of the diseases caused by most cestodes
usually subclinical or mild, and serious complications are usually rare
what is the name of the disease caused by both/either Taenia solium and taenia saginata?
cysticercosis
what is the life cycle of Taenia solium and Taenia saginata?
indirect
who is the final host for Taenia solium and Taenia saginata?
humans
who is the intermediate host for Taenia SOLIUM?
pigs
who is the intermediate host for Taenia SAGINATA?
cattle
describe the indirect life cycle of Taenia solium and Taenia saginata
humans shed eggs in feces (that they got by ingesting infected/undercooked meat), pigs and cattle eat contaminated soil/pastures, then the Taenia eggs hatch in their intestines and migrate to striated muscle and develop into cysticerci
describe the larval stage of Taenia, or cysticerci
a large, fluid filled cavity or vesicle or bladder found in the musculature of pigs and cattle with ONLY ONE LARVA INSIDE