Parasitology- Nematodes Flashcards
How many groups of muscles are there in nematodes and how are they arranged?
4 groups arranged longitudinally
Describe the nervous system of a nematode.
2 major nerve rings (oesophageal and rectal)
Four major nerves (dorsal, ventral and 2 lateral)
AcCh and GABA neurotransmitters
Where are anticoagulants produced in a nematode?
Dorsal gutter of the buccal capsule
What are the routes of transmission for nematode infection?
Transmammary
Oral
Percutaneus
Transplacental
What are some identifying features of rhabditids?
Rhabditiform oesophagus
Very small
Mostly free living and feed on bacteria
Match the following strongyloides species to their hosts (order: rhabditida): S. papillosus S. ransomi S. westeri S. stercoralis S. cati S. avium S. fuelleborni
Ruminants Pigs Horses Dog, cat, human Cat Poultry Primates
What are some key points about the lifecycle of Strongyloides nematodes?
Female is parthenogenetic
Eggs hatch quickly
The lifecycle can be heterogonic or homogonic
Autoinfection is possible (S. stercoralis)
Prenatal infection is also possible (S. ransomi)
So is trans-colostrum infection (ransomi and westeri)
What is the prepayment period for strongyloides nematodes?
5-12 days
What are the three stages in the pathogenesis if S. ransomi?
Invasive (dermatitis)
Pulmonary (pneumonia)
Intestinal (leads to diarrhoea and reduced growth)
What are some methods that can be used in the diagnosis of strongyloides nematodes?
What are some treatment options?
Faecal floatation (eggs)
Baermann technique (larvae)
In vitro culture
ELISA
Treatment: ivermectin and oxibendazole
What are some features of trichostrongyloid nematodes?
Vestigial buccal capsule
Copulatory bursa
Direct lifecycle
SI or abomasum
What are the effects of trichostrongyloid nematodes on the host?
Villous atrophy Diarrhoea Hypoproteinaemia Anorexia Reduced absorption of calcium and phosphate Reduced bone growth
How does the host respond to trichostrongyloid infection?
If greater than 5 months old, and if they have a worm burden >3000 then they mount a Th2 response.
▪️goblet cell hyperplasia- increased mucus
Mucus entangles worms and paralyses them
▪️eosinophils and mast cells in lamina propria kill larvae and lead to expulsion on worms
What are some identifying features of cooperia?
Cephalic vesicle
Striations in oesophageal regions
No gubernaculum
Spicules have wing-like expansion in mid-region
What is the prepatent period for the wire worm (cooperia)?
Can they go through hypobiosis?
15d
YES!
What are some identifying feature of nematodirus?
Coil around villi Spicules merge distally Cephalic vesicle Female with spiked tail Very large eggs!!! L1 to L3 in egg
What is the prepatent period for nematodirus? (Same for Haemonchus)
21d
What are the pathological effects of haemonchus on the host?
Microcytic, hypochromic Anaemia (feed 0.05ml per day) Hypoproteinaemia Reduced exercise tolerance Sudden death NO DIARRHOEA!!
What is the mechanism by which animals can self cure against haemonchus?
When a threes hold is reached an IgE response is mounted which sensitised mast cells. They then release vasoactive molecules that cause vascular exudation, smooth muscle contraction and eosinophils infiltration.
What are some features of ostertagia?
Cervical papillae
Spicules terminate in 3 stubby hooked processes
Small vulval flap
What effects does ostertagia have on the host?
pH rises to 6 Protein digestion stops Plasma pepsinogen rises Hypergastrinaemia Hypoproteinaemia Anorexia Diarrhoea
What are the differences between type 1 and type 2 ostertagiasis?
Type 1:
Young animals
Spring
Type 2: 2-4 yo Autumn Larvae emerge synchronously Precipitated by stress
