Strongylida 1 Flashcards
phylum Nematoda general characteristics?
- body a long thin tube
- exoskeleton- cuticle
- plus a hydrostatic skeleton + muscle allows for locomotion
- straight gut with highly variable pharynx
- sexes are separate
what do Phylum Nematoda morphological elaborations allow them to do?
Nematoda to be concentrated around openings
- mouth
- excretory ducts
- gonadal openings
Basic Nematoda development
- Typically egg, L1, L2, L3, L4, Adult
- L1 + L2 usually free living
- L3 = infective, transitional stage
- L4 (preadult) = migratory in definitive host
- Adult
Orders of bursae nematodes?
- Order = Strongylida
Non-bursate nematodes orders (6)
Rhabditoidea - strongylodies Ascarididoidea - ascarids oxyuroidea - pinworms Trichinelloidea - Trichinella Habronematoidea filarioidea - filariids
General information of the order strongylida?
(bursate nematodes)
most important and diverse group of parasitic nematodes
parasites of Gi Tract or lungs
only males have bursa
what is a bursa?
– Fan-like structure at posterior end, grasps female for copulation
– Bursal rays of taxonomic significance
Ancylostomatoidea, general characteristics?
- Hook worms
- Buccal capsule well developed
- Buccal capsule bent dorsally
- Teeth or cutting plates at mouth opening
- Adults in small intestines, carnivores, ruminants
Strongyloidea, general characteristics
- buccal capsule well developed
- buccal capsule not bent or ventrally
- leaf crowns usually present
- Adults of most occur in large intestines and/or caecum
- Adults in L1 of horses, ruminants
Trichostrongyloidea, general characteristics
- Buccal capsule vestigial
- Bursa well developed
- Leaf crowns usually absent (may be extremely reduced)
- Adults in upper GIT (Abomasum/stomach or small intestine) All herbivores (common), one in cats
Metastrongyloidea, general characteristics?
- buccal capsule vestigial
- bursa vestigial
- adults in lungs/pulmonary vasculature
- cattle, cats, rats (rat worm or minor veterinary and public health significance)
life cycle of strongylids
- simplest life cycle seen in superfamily trichostrongyloidea
- egg in faeces
- L1 in faeces
- after two moults develops into L3
- L3 escapes faeces, migrates in environment
- L3 is eaten
- L4 in small intestine (sometimes penetrate mucosa)
- Adult worms in Gi tract of host
Trichostrongyle life cycle?
- eggs pass in faeces
- embryonate in faeces (24hrs)
- After 2 moults L3 moves into surrounding soil, escaping the faeces
- L4 usually enter the mucosal lining of the host
Trichostrongyle eggs embryonate based on what factors? (3)
- moisture
- oxygen
- heat
Explain the trichostrongyles tissue stage?
- usually this is L4
- entering the mucosal lining of the host
- after there is no further tissue migration
- emerge after a few days as adults
- adults in intestine or stomach
Explain egg development of nematodes in faecal mass at day 0
Faecal mass
- moist/liquid consistency
- 75% of bacteria alive
- oxygenated at the surface
Eggs
- Scattered throughout mass
- embryonate
- 95% die to anoxia
- 5% hatch
Explain egg development of nematodes in faecal mass at day 1
Faecal mass
- Moist
- Crust forms- retains. moisture internally
Larvae
- hatch
- remain in moist inner layers
- feed on bacteria and moult
Explain egg development of nematodes in faecal mass at day 7
Faeces
- moist internally
- crust externally
- when rain occurs it allows larval escape
Larvae
- infective 3rd stage escapes if sufficient moisture
Explain egg development of nematodes in faecal mass, the importance of “Thin film of moisture”.
- <0.5mm
- allows larvae to crawl to the tops of grass
Explain the larvae movement and when they die and distance moved by larvae
- cannot move if no moisture
- most die in 4 weeks in the pasture
- distance travel is mostly under 30cm
What is Pilobolus?
- a fungus which when swollen, it fires things 6ft high - 8ft away
- parasites nematode hitchhikers
larval dynamic when there is a drought
- larvae become sealed in faeces and stop development
- larvae can survive in faces for 5-6months
- in droughts number of pats increase - lots of faecal matter with eggs
- larvae emerge after rain 50mm/48hrs (larval bursts)
larval dynamics in winter
- larvae stop development in faeces
- emerge at increased temp and increased moisture in spring
- pats accumulate on pasture then emerge at spring
larval dynamics in hot summers
high temp are lethal to pats and on pasture
