Intro to Helminths

Question 1

Are helminths ecto or endoparasites?

Answer 1

Endoparasites

• acanthocephala
• nematoda
• platyhelminthes
  
  • cestoda and trematoda

Question 2

________ and _______ are long, non segmented

Answer 2

Acanthocephalan and nematode

Question 3

Cestodes have ______ bodies

Answer 3

Long, segmented

- flat

Question 4

Trematodes are _______ shaped

Answer 4

Leaf-like/petal shaped

- flat

Question 5

Acoelomate

Answer 5

All parenchyma, no body cavity

• trematodes
• cestodes

Question 6

Pseudocoelomate

Answer 6

Have a body cavity, but the mesoderm does not coat the organs (are more likely to move around)

• nematodes
• acanthocephalans

Question 7

Trematodes have a _____ digestive tract

Answer 7

Partial

- cecum does not have a direct opening to the outside

Question 8

Cestodes have _____ digestive tract

Answer 8

No!

• no mouth opening = no digestive tract
• acquire nutrients via absorption thru integument

Question 9

Nematodes have a ________ digestive tract

Answer 9

Complete

- feeding mechanism with an excretory system

Question 10

Dioecious

Answer 10

Split, separate sexes

• clear male and female with their own repro organisms
• thorny headed worms and nemotodes
• males smaller than females
• heartworm males have a coiled tail and are smaller

Question 11

Monoecious

Answer 11

Hermaphrodites

• one body system, one set of repro organisms
• cestodes: every segment is its own living entity
• trematodes: contain both sets of repro tracts

Question 12

General characteristics of nematodes

Answer 12

• long, round, unsegmented
• pseudocoelomate
• complete digestive tract
• dioecious
  (barber pole worm)

Question 13

General characteristics of cestodes

Answer 13

• long, dorsoventrally flat, segmented
• acoelomate
• lack digestive tract
• monoecious

Question 14

General characteristics of trematodes

Answer 14

• dorsoventrally flattened, unsegmented
• acoelomate
• incomplete digestive tract
• monoecious

Question 15

What is the one exception of monoecious trematodes?

Answer 15

Schistosomes

• present in dogs, male and females are separate, but they have a close relationship
• females lie in canal of the male
• usually found in veins

Question 16

General characteristics of acanthocephalans

Answer 16

• long, round, unsegmented
• pseudocoelomate
• lack digestive tract
• dioecious

Question 17

No body cavity, solid with embedded structures, body usually flattened

Answer 17

Cestodes and Trematodes

Question 18

Body cavity, coelom or pseudocoelom, body usually cylindrical

Answer 18

Acanthocephala and nematoda

Question 19

Anterior end armed with proboscis, no digestive tract

Answer 19

Acanthocephala

Question 20

No proboscis, digestive tract present

Answer 20

Nematoda

Question 21

No digestive tract, segmented body

Answer 21

Cestoda

Question 22

Digestive tract, no segmentation

Answer 22

Trematoda

Question 23

Acanthocephala

Answer 23

Thorny headed worms

• long, cylindrical
• anterior spiny proboscis
• no digestive tract
• pseudocoelomates (hydrostatic system)

Question 24

Hydrostatic system

Answer 24

Pushes proboscis in and out
- if the worm is in the intestine, then the thorny head is used for attachment = lesion that goes thru the intestine (peritonitis)

Question 25

Acanthocephalans are _______

Answer 25

Dioecious | - female is larger!!

Question 26

General acathocephalan life cycle

Answer 26

Mature adults in DH intestine, produce eggs --> eggs shed in feces --> eggs in environment, contain acanthor --> IH ingests eggs with acanthor --> acanthor (infective stage) --> acanthella --> cystacanth (infective stage for definitive host) --> DH ingests IH

Question 27

Acanthocephalans cause disease due to their _____

Answer 27

Proboscis - amount of inflammation or other damage depends on various factors (inclu proboscis morphology) - clinical signs are rare unless perforate intestines

Question 28

Macracanthorhynchus hirudinaceus

Answer 28

- DH: swine - IH: grubs (larvae) - -> dung beetle, may beetle, water beetle (also adult beetles) - may be zoonotic

Question 29

M. hirudinaceus life cycle

Answer 29

DH: adult worms in SI --> eggs in environment --> IH: dung beetles --> DH ingests IH - PPP: 2-3 months

Question 30

M. hirudinaceus pathogenesis and clinical signs

Answer 30

Usually asymptomatic - possible GI signs - enteritis/pain, decrease feeding or weight gain, diarrhea

Question 31

M. hirudinaceus diagnosis

Answer 31

Eggs in pig feces, requires dense, high SG float solution - almond shaped - multiple layers - dark brown Recovery adult throny-headed worms at necropsy

Question 32

Must differentiate M. hirudinaceus from _______

Answer 32

``` Ascaris suum (nematode) - look for proboscis ```

Question 33

M. hirudinaceus treatment and control

Answer 33

No approved anthelmintics - ivermectin, some benzimidazoles - control intermediate hosts - regular disposal of feces

Question 34

Macracanthorhynchus ingens

Answer 34

``` DH: mainly raccoons IH: milipedes - similar life cycle to M. hirudinaceus - no clinical signs - off-label treatment (ivermectin) ```

Question 35

Must differentiate Macracanthorhynchus ingens from

Answer 35

Cestodes - ex: taenia spp in dogs - also some large nematodes