Lecture 6: Strongyles #1 (

Question 1

Your friend doesn’t know who his “true” strongyles are.. Poor guy needs you to describe who his real “true” strongyles are. (List common characteristics)

Answer 1

• well developed buccal cavity and buccal capsules
  
  • capsule often has corona radiata (leaf crown)
• teeth or cutting plates at base of buccal cavity
• males have large bursa
  
  • spicules, thin, flexible

Question 2

Label the attahced photo of strongyle.

Answer 2

Question 3

What sex is this strongyle?

Label the attached photo.

Answer 3

Male strongyle

Question 4

Your mom is worried the “true” strongyles’ life style isn’t suited for her baby. If you can just explain to her what they do (life style characteristics), I’m sure she’ll ease up on your choice of parasites.

Answer 4

Direct life cycle

Adults mainly parasites of host GI tract

Infection usually acquired by ingestion of L3

Primarily parasites of herbivores

Question 5

A veterinarian you’re following tells you one of his patients has blood worms (AKA red worms.) As you laugh nervously and try to act casual you rack your brain for what the hell these terms are common names for. Any ideas?

Answer 5

common names for Equine strongyles

Question 6

True/False:

1) small strongyles are less pathogenic than large strongyles.
2) Small strongyles are known for their well-developed globoid buccal capsule
3) Females of ONLY large strongyles are oviparous, while small strongyles are viviparous.

Answer 6

1) True

Large strongyles are more pathogenic

2) False

small strongyles have short buccal capsule (more shallow)

large strongyles have the well developed globoid buccal capsule

3) False

Both large and small strongyles are oviparous

Question 7

1. ) Your friend wants you to differentiate between strongyle genus/species, how can you do this for your friend?
2. ) What are some characteristics of strongyle type eggs?

Answer 7

1.) You can’t, strongyle eggs cannot be readily identified to genus/species

2.) smooth surfaced

ellipsoidal shells

contain an embryo in morula stage when laid and passed out with the feces

Question 8

Which is the large or small strongyle from the attached photo?

Answer 8

Large strongyle on left, small strongyle on right

Large strongyle have large buccal cavities

small strongyle has a Coke bottle appearance

Question 9

It’s that time of the year again and you and your buddies go to a local watering hole to seek out some parasitic friends for the night. You’re into 3-teeth strongyles, what’s the name of tonight’s lucky strongyle?

You’re friend that into weird stuff likes his strongyles with no teeth, but can’t remember the name of strongyle. Could you help your friend out?

Answer 9

3- teeth: strongylus equinus

no teeth: strongylus edentatus

Question 10

Your drunk and downright vulgar friend just saw his soulmate-level match with a strongyle he just saw strolling past him at the bar. He sees the strongyle wink and flash a beautiful 2-teeth smile. What’s the name of this lovely parasite?

Answer 10

2-teeth: strongylus vulgaris

Question 11

Which strongyle spp. are each of these in the attached picture?

Answer 11

from left to right:

strongylus vulgaris

strongylus equinus

edentatus edentatus

Question 12

Label the attached photo.

Answer 12

Question 13

1. How do equine strongyles get nutrition?
2. Where do Strongylus spp. adults spend their time?

Answer 13

1. They suck blood from host
   
   1. plug of gut mucosa sucked into buccal cavity
   2. tetth lacerate mucosal plug
      
      1. pathology is related to these events
2. In the cecum &/or colon and shed eggs in feces

Question 14

Review: Where do the adults from ascarids, pin worms, and strongyles live and cause pathology to host?

Answer 14

ascarids: live in small intestine

pin worms: live on perineum

strongyle: live in cecum/colon

Question 15

What stage is the strongyle in in the attached photo?

Answer 15

infective sheathed L3

L3 uses sheath from L2

Question 16

True/False: To raise the odds of being eaten by a host, L3 larvae will travel closer to dirt and exhibit negative phototropism.

Answer 16

False

L3 exhibit positive phototropism

exhibit negative geotropism (go away from dirt)

Question 17

What does the Stongylus spp. L3 do when ingested in a new host?

Answer 17

L3 rid of sheath

then penetrate the mucosa of GI tract

in 1 week will molt into L4

Question 18

1. ) If you wanted to meet up with a S. vulgaris larvae in the body, where would you find the in blood supply?
2. ) How long does it take the larvae to travel there?
3. ) How long is the prepatent period? (time from ingestion of L3 to eggs detectable in feces)

Answer 18

1. ) Cranial mesenteric artery and other blood supply to GI tract
2. ) 2 to 3 weeks
3. ) 6 months

Question 19

Describe the larval migration for S. vulgaris once L3 molts into L4 in submucosa.

Answer 19

• penetrates small arterioles of GI tract
• migrate within intima to larger artery branch
  
  • cranial mesenteric artery in 2 to 3 weeks
  • cannot penetrate the internal elastic lamina
• Continue to migrate iwhtin intima for a total of 2 to 4 months
• return to intestine via arteries to subserosal capillaries
• occludes blood flow to capillaries
• L4 destroys capillaries and releases into gut wall
  
  • encapsulated in nodules in gut wall and develop into L5
• L5 rupture out of nodules into lumen of cecum/colon and mature into adults

Question 20

What’s happening in the attached photo?

Answer 20

Question 21

What can result from larval migration of Strongylus vulgaris within arterial intima of cranial mesenteric artery and it’s branches?

Answer 21

• arteritis or thrombosis
• fatal infarcation of gut wall
• aneurysms (bulge in artery) can develop
• altered intestinal motility
• predisposes to colic

Question 22

Describe the acute clinical syndrome created by S. vulgaris.

Answer 22

• foals and yearlings are prone after ingestion of large numbers of L3 in short period of time
  
  • pathology caused by early larval migration in gut wall and mesenteric arteries
    
    • sudden onset of fever
    • depression, lethargy
    • colic
    • death can occur within 2-3 weeks

Question 23

True/False:

1. ) Only foals and yearlings are prone to verminous colic created by S. vulgaris.
2. ) Verminous colic is more common than acute disease caused by S. vulgaris.
3. ) Verminous colic is usually more fatal than the acute disease caused by S. vulgaris.

Answer 23

1. False, verminous colic is found in all ages of horses, but can be more severe in younger horses
2. True, it’s a recurrent and intermittent colic
3. False, verminous colic is usually not fatal, but can be severe and acute

Question 24

What are some clinical signs of verminous colic?

Answer 24

• Ill-thrift
  
  • weight loss, rough hair coat etc
• Intestinal dysfunction:
  
  • diarrhea and/or constipation
• Anemia
  
  • normochromic, normocytic

Question 25

Describe the larval migration path of S. edentatus. (start with ingestion of infectious L3)

Answer 25

* L3 enters the gut mucosa and migrates to hepatic portal vein to the liver * create nodules in liver and develop into L4 * burst out of nodules and migrate freely in liver parenchyma for ~2 months * wander retro-peritoneally to cecum * emerge into cecal lumen as L5 then become adults

Question 26

1. ) How long is the prepatent period for S. edentatus? 2. ) What clinical signs would you see in an S. edentatus infested horse?

Answer 26

1. 6 to 11 months 2. Fluctuating fever 1. anorexia 2. lethargy 3. abdominal pain 4. diarrhea/constipation 5. anemia

Question 27

1. ) Describe the larval migration path of S. equinus. (start after L3 ingestion) 2. ) How long is the prepatent period for S. equinus?

Answer 27

1.) * L3 --\> L4 in nodules in cecum * L4 exit nodules and migrate to liver via peritoneal cavity * Migrate in liver for 2 months then migrate in peritoneal cavity * molts to L5 * L5 emerge in gut lumen then L5 molts to adult stage 2.) 9 months

Question 28

What are the prepatent periods for these large Strongylus spp.? * S. vulgaris * S. equinus * S. edentatus

Answer 28

* ~6 months * ~9 months * ~6 to 11 months

Question 29

True/False: 1. ) The efficacy of anthelmintics against small strongyles is much better then against large strongyles due to large strongyles being diffucult to remove due to increased size, 2. ) The best way to treat small strongyles is to treat the many spp. collectively as a group.

Answer 29

1. ) False, it's becoming an emerging problem that small strongyles have significantly smaller efficacy of anthelmintics. 2. ) True, treat the small strongyles (cyasthastomes) together

Question 30

Describe the life cycle, pre-patent period, and larval migration of small strongyles.

Answer 30

* Direct life cycle (like large strongyles) * pre-patent period (no hypobiosis): 6-8 weeks * larval migration: * undergo mucosal migration in large intestine * emerge into gut lumen and mature into adults * L3 can become hypobiotic: * persist in submucosal cysts in gut wall * emerge weeks to years later and complete cycle *