Worms and Flukes Flashcards
which are the most successful human parasites
nematodes
what are the 7 types of worm parasites
pinworms
common/giant roundworm
hookworm
whipworm
threadworm
tapeworm
blood flukes
distinctive features of pinworms?
-small, visible white roundworm
-humans are only host for entire life cycle
-in order to lay eggs, which require more O2 to develop, females emerge from anus and lay them on skin
how are pinworms transmitted
eggs ingested by the fecal oral route, from surfaces including clothes, or by swallowing dust containing eggs
who is infected by pinworms
almost all children, adults are asymptomatic
symptoms of pinworms
intense itching of perianal area - resolves w/in 6 weeks
pinworm treatment
Pyrantel
hand washing and normal hygiene reduces transmission and vaseline to perianal area prevents eggs from getting O2
common/giant roundworm distinctive features
-large
-humans are again the only host
- lung migration
what are giant roundworm eggs resistant to and susceptible to
resistant to chemical inactivation, susceptible to sunlight
- need to incubate several weeks to become infectious, but can remain viable for years
describe common roundworm lung migration
- larva inside eggs are ingested from contaminated soil
- hatch in small intest. and larvae burrow thru wall and carried to lungs in blood
- size of adult can result in blocking the intestine or bile or other ducts or perforations
symptoms of common roundworm
few eggs and worms can remain asymptomatic
-insomnia, malnutrition
how long will common roundworm infection last
1-2 years if left untreated and not reinfected (the lifespan of the adult)
common roundworm diagnosis
-eggs seen in stool specimens, which may also contain clearly visible adult
- high levels of eosinophils
common roundworm treatment
mebendazole
common roundworm prevention
improved sanitation, particularly human waste disposal
hookworm features
-eggs and early stage larvae mature in soil and give rise to motile larva that is able to penetrate the skin
- smaller, more often asymptomatic
- no physical damage but injure by attachment and sucking blood
hookworm transmission
- eggs resistant in the soil, eggs are larvae susceptible to sunlight
- eggs hatch in the soil and the developing larvae can live for several weeks in the absence of a host
hookworm symptoms
- larvae enters thru skin, usually the foot causing intense itching (ground itch)
- migrates thru the blood system to the lungs
- coughed upwards, swallowed and reside in small intestine
- anemia, fatigue, weight loss, pneumonia, eosinophilia
hookworm diagnosis
appearance of eggs in stool specimens on āO and Pā (stool test)
hookworm treatment
mebendazole
hookworm prevention
improved sanitation, shoes
whipworm features
- big
- thin coiled majority of the body is the esophagus that the worm threads into the mucosa of the colon
- no lung migration
whipworm clinical manifestations/pathogenisis
- mature or ineffective eggs are ingested directly or in food & hatch inside small intestine
- adults migrate into colon and reside for 4+ years ( no lung migration)
- light infections are asymptomatic
- severe infections = GI issues, rectal prolapse, weight loss, nutritional deficiencies, anemia (especially in children)
whipworm diagnosis
stool O and P exam shows whipworm eggs
whipworm treatment
bendazole with ivermectin
threadworm features
-like hookworm, larvae actively seek hosts and penetrate skin (foot)
- unique among helminths can replicate in the host
- also can replicate without a host in the soil (free-living cycle)
tapeworm features
- adult flatworm is a family of individuals
- segmented large worms that reproduce by fragmentation
-require human definitive host and a 2nd vertebrate host - adults are long lived
- eggs eaten by intermediate hosts
tapeworm hosts
- all except pork tapeworm requires 2 hosts, with humans as a necessary definitive host
- pork tapeworm humans can also be intermediate and only host
tapeworm diagnosis
bendazoles
tapeworm prevention
thorough cooking, adequate sanitation
blood flukes features
- reside in host organs other than intestine
- ## large visible animals
blood flukes aka
schistosoma
blood flukes transmission
- swimming larvae penetrate skin, travel in blood and inhabit veins draining intestine and bladder
-immune responses cause significant tissue damage
blood flukes prevention
avoid swimming in fresh water in high incidence areas
- 2nd most fatal parasite after malaria
