Test 3: Worms and Flukes Flashcards
Which of these are considered parasites in the field of infectious diseases?
a. protozoans
b. bacteria
c. some insects
d. a & c
e. all of these
D. protozoans and some insects
What is the biggest group of worms?
- nematodes (giant roundworm)
ascaris lumbicodes
What are the big 3 soil transmitted diseases?
- giant roundworm
- hookworm
- whipworm
- 4th: threadworm with endogenous/atuo-reinfection ability meaning it can multiply without going outside the body and multiply in the soil
What are the other 2 types of worms?
- tapeworms
- flukes
What can cause more human disease than any other infection?
- worms and flukes to low CDC reportability
What is the main distinction of hookworm?
- actively seeks human host by living on plant and going through human foot
What is the most important nematode worms?
- common roundworm: ascaris lumbridcoides (most common in tropics)
- whipworm: trichuris trichiura
- hookworm: necator Americanus and ancylostoma duodenale
- threadworm: strongyloides stercoralis
- pinworm: enterobius vermicularis (most common in US)
What is the most successful human parasite?
nematodes
How common are soil transmitted helminths in US?
no one knows
What is the #1 US prevalence worm?
- pinworms: enterobius vermicularis
- small, white
- humans are only host for the entire life cycle
- to lay eggs: requires more oxygen iso female will emerge from any and lay them on skin at night and dies
What is the habitat and transmission of pinworms: enterobius vermicularis?
- more often in urban areas (highest in US)
- fecal-oral route from surfaces or by swallowing dust
What is the epidemiology of pinworms: enterobius vermicularis?
- most common parasite in US
- almost all children infected with siblings in same household infected
What is the pathogenesis of pinworms: enterobius vermicularis?
- intense itching of perineal area
- resolves about 6 weeks
What is the dx, tx, and prevention of pinworms: enterobius vermicularis?
- dx: scotch tape
- tx: pinworm medicine: pyrantel, petroleum jelly can prevent eggs from getting oxygen
- prevention: hand washing and normal hygiene
What is the #2 US associated but #1 medically important helminth in the US and world?
- nematode common roundworm: ascaris lumbricodes
What is the distinctive features of nematode roundworm: ascaris lumbricodes?
- large roundworm
- most abundant in tropics
- unusual and lung migration
What is the habitat and transmission of nematode roundworm: ascaris lumbricodes?
- Southeast Asia
- eggs are resistant to chemical inactivation but susceptible to sunlight so must incubate several weeks in warm soil to become infectious
- can remain viable for years
What is the epidemiology nematode roundworm: ascaris lumbricodes?
- human waste as fertilizer and consuming veggies
What are the clinical manifestations of nematode roundworm: ascaris lumbricodes?
- larva inside eggs are ingested from contaminated soil
- hatch in small intestine and larva burrow through wall and carries to lungs in blood
- size of the adult can block intestine or ducts/perforations but with many worms
- if few= asymptomatic
- symptoms: insomnia, GI problems, malnutrition
- infection untreated: 1-2 years which is the life span of the adult
What is the dx, tx, and prevention of nematode roundworm: ascaris lumbricodes?
- dx: eggs seen in stool specimens with clearly visible adult
- tx: mebendazole
- prevention: improved sanitation of human waste disposal
What is #3 US associated helminth?
- hookworm: necator americanus
What are the distinctive features of hookworm: necator americanus?
- motile larva that penetrates skin (typically foot)
- much smaller, usually asymptomatic
- no damage but attachment and such blood could cause anemia
What is the habitat and transmission of hookworm: necator americanus?
- widespread mostly tropics
- eggs are restraint in soil and must be warm. susceptible to sunlight
- eggs hatch in soil
What is the epidemiology of hookworm: necator americanus?
- walking in latrine areas
What are the clinical manifetions, pathogenesis of hookworm: necator americanus?
- ground itch
- migrates though blood to lungs
- coughing upwards, swallow, and then revised in small intestine
- heavy burdens can cause anemia, fatigue, wt loss, pneumonia like sx, eosinophilia
What is the dx, tx, prevention of hookworm: necator americanus?
- dx: omars thing
- tx: mebendazole
- prevention: improved sanitation, shoes to block infection
What is the #4 US associated helminth?
- whipworm: trichurus trichuria
What are the distinctive features of whipworm: trichurus trichuria?
- big, whip like
- thread into mucosa of large intestine
- no lung migration
What is the habitat and transmission of whipworm: trichurus trichuria?
- outdoor latrines
- nightsoil
- most prevalent in children
What are the clinical manifestations and pathogenesis of whipworm: trichurus trichuria?
- hatch inside small intestine
- migrate into colon and rside for 4+ year
- no lung migration
- often asymptomatic
- severe infection: rectal prolapse
- in children sometimes: weight loss, nutritional deficiencies, anemia
What is the dx, tx, and prevention of whipworm: trichurus trichuria?
- dx: Omar thing
- tx: combing bendazole with ivermectin
What do we need to know about 4th threadworm?
- in kentucky, Tennessee (appalachians)
- similar to hookworm in that is actively seeks host and penetrates skin of foot
- uniquely, can replicate in the host and replicate without a host in the soil
What is another name for cestode?
tapeworm
What is another name for trematodes?
fluke
What is the distinctive feature of tapeworm/cestode?
- each body segmentation that fragments off is a full organism
How do tapeworm/cestodes reproduce?
- fragmentation
What do tapeworm/cestodes require?
- human definitive host
- animals typically as intermediate host
How are tapeworms transmitted?
- not an issue for vegetarians
- the 2nd host is in cows or eggs where the eggs mature
- consumed in meets in muscle cysts and reside in definitive host of a human
How long do tapeworms lived?
- long lived (years or decades), shed eggs or segments with eggs
- eggs eaten by intermediates hosts like cow and mature to juveniles that migrate into muscle and form cysts
- cestodes are acquired when a human (definitive host) consumes a second intermediate hosts with tissue cysts
What is it called when you have an adult worm that resides in the gut?
- taenasis
Why is the pork tapeworm/ Tania sodium more dangerous?
- only require 1 host. humans can be the intermediate host and definitive host
- this allow for muscle cysts or brain cysts in humans= cysticercosis
What is the fish tapeworm called?
- d. latum in salmon
(different genus)
What is the dx for cestode?
- stool with worm segments
What is the tx for cestode/tapeworms?
- bendazoles
What is the prevention for cestode/tapeworm?
- thorough cooking and adequate sanitation
(pork requires adequate cooking and sanitation)
T/F: Blood flukes/schistosoma can reside outside of intestines
True!
How are blood flukes/schistosoma transmitted?
- swimming larva penetrate skin, travel in blood, inhabit veins draining intestines and bladder (in fresh water)
- the immune response is what cause the significant tissue damage
What is the tx for blood flukes/schistosoma?
- prazquantel
What is the prevention for blood flukes/schistosoma?
- avoid swimming in fresh water in high incidence areas like Africa
