Nemotodes Flashcards
Name the 5 main nematodes that we need to learn + name there host/ site
- Telodorsagia Circumcincta = Abomassum of ruminants
- Trichostrongylus spp. = Small Intestine + Abomassum of ruminants, Stomach of horses
- Cooperia spp. = Small Intestine of ruminants
- Haemonchus Contortus = Abomassum of sheep
- Nematodirus battus = Small Intestine
Define ‘Pre-Patent Period’
time taken from time of infection to detection of eggs in faeces
What is the meaning of ‘hypobiosis’?
arrested development of larvae within host in response to trigger received by free living L3 (< temp)
Describe the identification features of telodorsagia circumcinta + how to distinguish b/w male/ female
- cervical papillae (male + female)
- males have bursa + spicules
- females are larger + have pointed tail end- may be able to see eggs in uterus
Describe a typical Trichostrongyle lifecycle
- direct (no intermediate host)
- worms in abomassum > mate > females produce eggs > eggs develop in faecal pat > L1 hatches > feeds + moults to L2 > L2 moults to L3 > L3 (ensheathed) released from faeces by rain > L3 ingested > develops to L4 + L5 > L5 emerges + matures to adult
Name to nematodes that follow a typical Trichostrongyle lifecycle
Telodorsagia Circumcinta, Trichostrongylus spp., Cooperia spp., Haemonchus Contortus
What are the clinical signs of Telodorsagia Circumcincta infection?
weight loss/ poor weight gain, diarrhoea, dehydration, death
What disease is cause by large numbers of Telodorsagia Circumcincta?
PGE (Parasitic Gastro- Enteritis)
What is a parasite?
An organism that is dependent metabolically on another where the organism benefits at the expense of the other
Describe the anatomy of the digestive system of a nematode
Mouth > Buccal cavity > Oesophagus > Intestine > Anus
How do large numbers of Telodorsagia Circumcinta cause disease in ruminants?
>pH in abomassum which causes loss of bacteriostasis = ‘leaky’ abomasal mucosa
Describe the typical hosts for infection by Telodorsagia Circumcincta
1st season lambs
Describe the identification features of Trichostrongylus spp.
- well developed excretory notch
- males have a bursa + short spicules
What disease does large numbers of Trichostrongylus cause?
PGE (Parasitic Gastro-Enteritis)
What are the clinical signs of Trichostrongylus infection?
black scour, weight loss/ poor weight gain, poor skeletal growth
What does Trichostrongylus cause leading to the clinical signs?
vilous atrophy, haemorrhage
What season does Trichostrongylus spp. typically cause infection + what is their typical host?
Autumn disease of store lambs
Describe the identification features of Cooperia spp.?
- Coiled appearance
- Small cephalic vesicle around head
- Males have short stumpy spicules
What does heavy infections of Cooperia cause?
catarrhal enteritis, vilous atrophy, oedema of intestinal mucosa
Describe the lifecycle of Nematodirus battus
Unembryonated eggs shed in faeces onto pasture > L1 > L3 develops in egg > L3 hatches > L3 ingested > L3- L4 reaches lumen of SI > L4 burrows into mucosa of SI > L5 emerges + adults mature in SI
Describe the typical identification features of Nematodirus battus
- ‘tangled cotton wool’
- bubble-like cephalic vesicle
- males have long thin spicules
- females have large eggs within uterus
- thin + coiled w/ distinct buccal capsule
What does infections of large numbers of Nematodirus battus cause and why?
Developing L5 destroy mucosa = catarrhal enteritis, vilous atrophy, fluid + nutrient absorption disrupted
What are the clinical signs of Nematodirus battus infection?
sudden outbreaks of acute watery diarrhoea, inappetence, dehydration, abdominal pain/ weight loss
Describe the typical host of Nematodirus battus
lambs 4-12 wks old
Describe the identification features of Haemonchus contortus
- Large
- Cervical papillae
- Females have white ovaries wrapped around gut
- Males have asymmetrical dorsal lobe
What does infection of Haemonchus Contortus cause and why?
Adults feed on blood = erosion of abomasal wall, severe haemorrhagic gastritis
What are the clinical signs of Haemonchus Contortus infection?
anaemia, pale mucous membranes, ‘bottle jaw’ appearance
Describe the typical host of Haemonchus contortus + time of year of infection
1st season grazing lambs, August/ September
Identify this worm…
Telodorsagia circumcinta
- male = smaller than female
Identify this worm egg and describe what features enable this identification…
Telodorsagia circumcincta
- barrel-shaped
- undifferentiated -> contain undeveloped morula
- undistinguishable from other trichostrongyle eggs
