1. Lecture: introduction to nematodes and strongyles

Question 1

How can roundworms be morhologically distinguished from other helminths?

Answer 1

• Simple mouth: 3 large lips, small denticles on each lip, no buccal capsule
• males are slightly curved posteriorly
  -males have 2 spicules no bursa
  -oesophagus is bulb shaped (some not have)
  -eggs very resistant, thick shaped, zygote or larva inside
  -male tail is spirally coiled
  -females larger than males

Question 2

How does mouth of roundworm affect their diet?

Answer 2

• small mouth: eat mucus from intestines and cells , not causing lesions

Question 3

What types of mouth do roundworms have?

Answer 3

simple mouth, BUCCAL CAPSULE (teeth/blades) can be surrounded by leaf crown

Question 4

accessory male organs - what belongs to it?

Answer 4

copulatory spicules
copulatory bursa

Question 5

what does molting mean?

Answer 5

shed cuticle = grows (usually 4 molts)

Question 6

how many larval stages are there in life cycle of roundworms?

Answer 6

L1-L4 (fift stage=adult)

Question 7

general life-cycle of roundworms and phases?

Answer 7

1. larva develops in envi
2. direct cycle : 2 molts outside
3. indirect cycle : 2 molts in intermediate host
4. larva molts 2 in final host

Question 8

what is arrested larval development?

Answer 8

resting from habitual stages ; in final host (hypobiosis) =inhibited larval development = stop of development of nematode
- happens only in final host=hypobiosis

Question 9

what are triggering factors for arrested larval development to occur?

Answer 9

-seasonal arrestment - hypobiosis- cold/autumn/winter or dry summer
-immunity
-overcrowding

Question 10

why arresting stage is important?

Answer 10

• parasite distribution>increase nematode survival
  -maturation of arrested larvae increases envi.contamination

Question 11

Periparturient rise in faecal egg count-why does it occur/how does egg count increase?

Answer 11

synonym: post-parturient egg rise (PPEG) -> happens around parturition> incr.no. of nematodes in feces > IgA in intestines but when animal starts lambing travels to milk-immunity goes down in lambic and rise the egg count in feces ; bc not enough immunoglobulins to fight parasite

Question 12

is it important to distinguish small strongyle species?

Answer 12

yes, since small strongyles are the ones that are non-migrating strongylids (large migrate)

Question 13

where you can find small strongyles in horse organism?

Answer 13

• larvae in caecum, inside nodules.

Question 14

why are small strongyles stages most pathogenic horse parasites?

Answer 14

high damage risk if large number of encysted L4 larvae emerge from mucosa at same time ; at L3 larvae enter large intestinal mucosa

Question 15

what is larval cyathostominosis?

Answer 15

life-cycle containing both free living phase AND parasitic phase (=direct and indirect phase)

Question 16

is result of stool sample reliable in case of larval cyathostominosis?

Answer 16

• FEC = Fecal Egg Count not valuable in case of larval cyathostominosis

Question 17

Life-cycle of small strongyles-more specifically: how long is prepatent period of small strongyles usually and if dormant/hypobiotic larval development occurs?

Answer 17

• prepatent period: 2-3 months due to winter period
• early L3 may enter hypobiosis (2-3 months)

Question 18

how long is development in external environment?

Answer 18

envi. 2 weeks

Question 19

what causes pathogenesis of small strongyles and what are clinical signs?

Answer 19

• lesions in mucosa after winter > November heavy infections > goes arrested > massive tissue destruction, lesions. ENCYSTED LARVAE IN LARGE INTESTINE.
• CS: weight loss, subcutaneous oedema, anemia, profuse-sudden onset of diarrhea > protein loss (hypoalbuminaemia) and oedema
• adults in intestine: unspecific ,shaggy coat

Question 20

do small strongyles have migratory phase?

Answer 20

no, they are non-migrating strongyles

Question 21

are species of large strongyles distinguished from each other?

Answer 21

yes by size/presence/shape of teeth

Question 22

why are large strongyles clinically most important and devastating parasites in horses?

Answer 22

due to migratory phase

Question 23

do large strongyles have migratory phase?

Answer 23

yes

Question 24

morphological feature of large strongyles-what is buccal capsule like-what’s inside it and why is it important in their pathogenesis?

Answer 24

• strongylus edentates adult (no teeth) draws lug of mucosa into its buccal cavity
  -adults feeding on plugs of intestinal mucosa and consume blood
• large plug capsula-plug in capsula cause ulcers and scars

Question 25

life cycle of large strongyles: species differences in migration phase?

Answer 25

-Strongylus vulgaris migrate to cranial mesenteric artery
-Strongylus edentatus migrate to liver > peritoneum and molts
- Strongylus equines migrate to liver parenchyma > pancreas or peritoneal cavity

Question 26

prepatent period S. vulgars-edentatus-equinus?

Answer 26

• vulgaris:6-7 months
  -edentatus : 10-12 months
  -equinus: 8-9 months

Question 27

pathogenesis and disease symptoms caused by large strongyles?

Answer 27

-adults feeding plugs of intestinal mucosa and consume blood>ulcers, scars, hemorrhages, anemia, emaciation
-severe infection with s.vulgaris:thrmboses: 1st weeks PI

Question 28

what diagnostic methods are used to diagnose equine enterostrongylidosis?

Answer 28

rectal examination-palpation of cranial mesenteric artery

Question 29

morphology of strongyle type eggs and L3 larvae? (large)

Answer 29

eggs: ellipsoidal shape, 70-100 micrometers, smooth and thin surface, embryo content, brownish
-L3 larvae? crystals inside ; oesophagus

Question 30

main treatment methods of strongylidosis?

Answer 30

-broad spectrum anthelmintics against adults
-against larval cyathostomosis 1x/year after grazing season-foals and young horses

Question 31

prevent and control large strongyles ?

Answer 31

monitor 1-3 x / year: FEC and response to treatment FECRT