Helminth Worms

Question 1

Helminth worm characteristics

Answer 1

eukaryotic and multicellular

Question 2

2 main groups of helminths

Answer 2

1. Platyhelminthes

2. Nemathelminthes

Question 3

Platyhelminths

Answer 3

flatworms
tapeworms and flukes
reduced nervous, excretory and digestive systems
Cestoda and Trematoda

Question 4

Nemathelminthes

Answer 4

roundworms
nematodes
complete digestive system
2 different sexes
Enterobius
Ascaris
Trichinella
Necator

Question 5

helminth infection

Answer 5

increases eosinophil concentration in blood

Question 6

Cestoda

Answer 6

tapeworms

Platyhelminths

Question 7

Cestoda physical characteristics

Answer 7

scolex- attaches to host intestinal wall with hooks/ suckers
neck- forms segments
proglottids- body segments
absorbs/secretes across body wall

Question 8

Cestoda reproduction

Answer 8

mostly hermaphroditic
fertilization occurs in middle proglottids
older proglottids produce mature eggs which are released in feces
adult tapeworm develops in intestine of 1st host
larval stages develop in brain, muscle, eyes, liver or heart of 2nd host

Question 9

Cestoda genuses

Answer 9

Taenia
Echinococcus
Dyphillobothrium

Question 10

Taenia saginata

Taenia solium

Answer 10

beef tapeworm
pig tapeworm
Symptoms: vague abdominal pain and nausea, anemia
1. cow eats grass with eggs in feces
2. eggs hatch into larvae in intestine
3. larvae leave intestine and move into body
4. larvae form cysticerci in skeletal muscle
5. human eats cow
6. cystisceri hatch in intestines to form adults
7. adult anchors with scolex, forms proglottids and eggs and those released into feces

Question 11

difference between Taenia saginata and Taenia solium

Answer 11

Taenia solum forms cysticerci in human

Question 12

Echinococcus

Answer 12

dog, coyote and wolf tapeworm
dog host the adult
human hosts the larvae
1. grazing animals ingest the eggs from canine feces
2. eggs for larvae in grazers
3. hytadid cysts form in muscle
4. dog eats infected grazer
GROSS FACT 5. dog licks human

Question 13

Dyphillobothrium

Answer 13

fish tapeworm
common in Great Lakes region, Alaska, Canada
caused by eating raw fish, salmon, sushi
adults form in humans

Question 14

Trematoda

Answer 14

Clonarchis
Schistosoma
flukes
flat, unsegmented
oral/ ventral sucker attach to host
nutrients through mouth or across body wall
fecal contaminated water; sewage

Question 15

Trematoda reproduction

Answer 15

hermaphroditic or separate male/female forms

Question 16

Clonarchis

Answer 16

Asian liver fluke
1. adults form in liver
2. produce eggs which are excreted into water with feces
3. eggs form migratory miracidia larvae that infect snails
3. miracadia larvae form 2nd migratory form in snails called cercariae
4. cercariae infect fish and form metacercariae (cysts) in fish
5. humans eat fish, metacercariae form larvae and move to liver
EGGS-MIRACIDIA-CERCARIAE-METACERCARIAE-LARVAE

Question 17

Schistosoma

Answer 17

blood fluke
human and snail hosts (do not require a 3rd host)
cercariae directly infect humans by burrowing through skin or hair follicles
adults form in intestinal veins, eggs released with feces
COOL FACT small female lives in body groove of larger male
ALSO they may live for 40 years in host

Question 18

Nemathelminthes

Answer 18

round worms
complete digestive system (mouth and anus)
2 different sexes

Question 19

Enterobius vermicularis

Answer 19

pinworm
human only host- 1 month egg to adult
most common worm infection in US
adults in large intestine- females lay eggs on butt at night, GROSS FACT human scratches ass and ingests it, hopefully by accident

Question 20

Ascaris lumbricoides

Answer 20

intestinal round worms
pig reservoir
most common worm infection in world
eggs in contaminated food
hatch, burrow through intestine wall into blood
GROSS FACT larvae develop in lungs and are coughed up, swallowed and move back to intestine to develop
eggs released in feces

Question 21

Trichinella spiralis

Answer 21

trichinosis
reservoirs- pigs, bears, cats, dogs, rats
1. larvae form cysts in muscles of 1st host
2. 1st host eaten by 2nd host, cysts form adults, produce more larvae
3. larvae move through blood to form cysts in muscle
4. cycle continues when 2nd host eaten by 3rd
humans infected when undercooked meat is eaten
GROSS FACT deer meat is disgusting

Question 22

Necator americanus

Answer 22

hookworm
no animal host for larval stage
larvae live free in soil
enter human through sores on feet
move through blood to lungs GROSS coughed up and swallowed
mouth plates anchor adults in small intestine
eggs released in feces
eggs hatch into larvae in soil
Symptoms- nausea, vomiting, cramps, bloody diarrhea, anemia