Parasitology 3 Flashcards
Ostertagia common name, size, location and features
(“brown stomach worm”) Size: ~9 mm Location: abomasum Features: • cervical papillae • spicules terminate in 3 stubby hooked processes • small vulval flap, not as large
Ostertagia circumcinta what are the 6 steps in the lifecycle and PPP
Life cycle: direct
1) L1-L3 in faeces (~ 2 wks) - environment
2) L3 ingested and animals become infected
3) exsheaths in rumen
4) migrates into the lumen of abomasal gland
5) moults to L4
6) L4 returns to lumen of abomasum
• PPP = 21 days
Ostertagia in sheep what is important with the lifecycle and list 7 effects on the host
HYPOBIOSIS - common (6 months)
• cause nodules in abomasum - due to inflammatory response
• Occurs in summer
• larvae become inhibited in spring, emerge in autumn
Effects on the host:
Important in south-east Australia (Victoria)
1) pH rises to 6
2) protein digestion stops
3) plasma pepsinogen rises
4) hypergastrinaemia
5) hypoproteinaemia
6) anorexia - leakage of nutrition and not absorbed
7) diarrhoea - decrease absorption
Ostertagia in sheep describe the effect on host
When in lumen destroy epithelial cells
- Increase mucus production
- Hypoplasia and metaplasia occurs of the epithelial cells
Also damage other cells:
1. Cells that produce acid - parietal cells
- Damaged so increase pH in abomasum
2. Cells that produce pepsinogen - chief cells
- Pepsinogen not converted into pepsin due to high Ph
- The pepsinogen will then be absorbed into the circulation - HIGH PEPSINOGEN
Combination of high pH and excretory products from worms LEADS TO
- Increase production in gastrin, locally absorbed, leading to hypergastrinaemia
Ostertagia in sheep immunity
The abomasum adapts to the parasite
• develops in older animals - younger animals are more susceptible
○ If older animals get infected generally have subclinical infections
• worm burden expelled
• remaining worms small & produce few eggs
Ostertagia, Ostertagi what is important about it, what does it lead to within the host and the 2 differernces from sheep
Most important nematode in cattle in temperate areas of the world
• basic life cycle similar to Ostertagia in sheep
causes nodules and oedema in abomasum
- severe infestation gives “Morocco leather” appearance
Differences from sheep:
1. Faecal mass as a reservoir for larvae
2. Inhibited larvae can emerge synchronously
Ostertagia, Ostertagi epidemiology of larvae, where found, emerge and when does hypobiosis occur
cattle dung pat - “helminthological time bomb”
○ water content and temperature within dung pat play crucial role in hatching of eggs and the development of larvae
• larvae can survive for extended periods in faecal pat
• emerge following rain
Hypobiosis not understood
Southern Hemisphere - in summer
Northern Hemisphere - in winter
What occurs with type 1 and 2 ostertagiasis and when occur in southern australia
Type 1 ostertagiasis - Winter
• young animals
• no immunity
• occurs in winter
Type 2 ostertagiasis - Autumn
• larvae emerge synchronously - L4 hypobiosis larvae - 1000’s emerge
• 2-4 year old animals
• induced by “stress” (calving) - IMMUNOCOMPROMISED ANIMALS
• occurs in autumn - during summer larvae undergo hypobiosis so when change in weather they emerge if immunocompromised
Trichostrongylus axei common name, host, location, size and features
Stomach hairworm
Host: primarily parasitic in cattle; can occur in sheep, horses, pigs, humans
- Wide host range
Location: abomasum/stomach (intraepithelial)
• size ~ 6 mm - smallest that occurs in the abomasum
Features
• spicules - unequal, dissimilar
Trichostrongylus axei pathogensis and epidemiology
Pathogenesis: - similar to Ostertagia • damages epithelium - develops within epithelial cells • protein lost into lumen • mucus produced, pH rises • 40,000 can kill lamb Epidemiology: • important in mixed grazing - Cattle and lambs
What are the 2 most important nematodes of sheep in south-east Australia
1) Trichostrongyles
2. ostertagia
What are the 3 main parasites of sheep and relative costs and what contributes to the production loss
1) Fly strike - 173.2
2) Lice - 81.1
3) liver fluke - 24.8
Production losses
• fleece weight and staple strength
• ewe live weight and fertility
• lamb growth rate
• ↓weaning weight - increased deaths
What are the 3 main parasites of beef and relative costs
1) cattle tick - 161.0
2) Buffalo - 98.6
3) Internal parasites - 93.6
Trichostrongyles of ruminants what occurs with infection, control vs eradication
• Infections always mixed
• All animals are infected all the time while grazing - some animals have a heavier burden that others
• Control rather than eradicate
○ eradication is impossible
§ would leave susceptible sheep and cattle
What are the 3 main targets of trichostrongyles lifecycle
1) Parasitic stage - what occurs within the host
2) Contaminating stage
- How does the egg survive on the pasture
3) Infectious stage
- How does the infectious stage survive on the pasture
What are the 5 features that affect the epidemiology of trichostrongyles
- Moisture - different rainfall zones within Australia help us predict the parasites that are present
- Temperature
- Grazing factors
- Host factors
- Management factors
List 2 ways moisture effect epidemiology of trichostrongyles
1) needed for development of L3 in faeces (infective stage)
2) larvae to migrate onto pasture
Lateral movement - assisted by heavy rain & flood (growth of fungal spores travel on)
Vertical movement - via dew drop movement (dusk and dawn as sheep eat and less UV)
Trichostrongyles why is temperature important and what occurs with low and high temperature
Important for development of eggs and larvae
mild Australian temperatures have little effect except: Haemonchus >10º C - requires a higher temperature
• low temperature can slow egg hatching & development in some species
• high temperatures shorten survival times of L3’s on pasture
Trichostrongylus Colubriformis and Rugatus what temperature occur with
T. Colubriformis
- Need higher temperature for eggs to hatch as generally higher temperature areas
T. Rugatus
- Occurs in dry areas so longer survival in areas with less moisture (humidity)
List and describe 3 grazing factors that affect the epidemiology of trichostrongyloidosis
1) not uniform grazing so uneven defecation -> avoid high parasite areas -> eventually grass will grow and sheep will eat and become infected
2) Type of vegetation - height and species -> higher more protection for L3 (infectious) larvae
3) stocking rate - high stocking rate initally heavier contaimination overtime reduce infection due to overgrazing (UV exposure)
List and describe 3 host factors that affect the epidemiology of trichostrongyloidosis
1) age - younger animals
2) genetic susceptibility - skewed worm burden and faecal egg counts
3) Breed differences - merinos more susceptible than , no breeds completely resistant
In northern hemisphere and southern hemisphere what are the season in which rises in faecal egg counts occur and why
Northern hemisphere in spring
1) Ewes that are going to give birth to lambs worm count increase in spring due to relaxation in immunity - increase susceptibility to L3s
2) Larvae who had undergo hypobiosis reactivated and lead to high faecal egg count in ewes
3) Faecal egg count reaches maximum in summer
Southern hemisphere in autumn - autumn rise phenonium
1) During summer get hypobiosis therefore ewes that give birth to lambs in autumn
List 4 management factors that affect epidemiology of trichostrongyloidosis
- Time of lambing
○ Autumn lambing - increase in faecal egg count as discussed above - Grazing management
○ Over or under grazing - Nutritional status of animals
○ If healthy can withstand higher burden of parasites
○ If low condition score can get large clinical signs in same amount of burden - Strategic use of anthelmintics
○ When in the lifecycle are we going to get the maximum - dependent on temperature and moisture for free-living stages
List 3 factors supporting hypobiosis and 2 supporting reactivated of inhibited larvae
Factors supporting hypobiosis
1) unfavorable climatic conditions - increase
2) immune status of animals
3) Density of GINs - if high amount of adults within L4 will undergo hypobiosis until they are naturally or chemically cleared and then resume their development
Factors supporting the resumption of the development of inhibited larvae
1) hormonal changes
2) alterations in the components of immune system during the PPR
3) density dependence of parasite
List 6 ways to diagnosis Trichostrongyloidosis and which is gold standard
- faecal egg counts
- faecal cultures
- molecular identification of trichostrongylid nematodes
- haematology, biochemistry and serology
- pasture larval counts
- total worm counts - GOLD STANDARD
How many eggs per day does Haemonchus, Trichostrongylus and Nematodirus lay
Haemonchus 5000-10,000 eggs/female/day
Trichostrongylus 10-200 eggs/female/day
Nematodirus 50 eggs/female/day
Faecal egg count what used for, how done and advantages and disadvantages
- Used to give a rough guide on worm burden in the herd
- Count eggs of parasite within a known volume of fluid - need to find the eggs per gram of faeces (epg)
Ad - can be carried out in the field
- host immunity may suppress egg production
- allows you to test chemicas
Dis - variability in degree of infection between individuals
- indicated presence of females only
- difficult to identify eggs to genus need to carry out larval culture
Faecal cultures what used for, advantage and disadvantage
• identification of nematode larvae
Adv - permits determination of the composition of worm burdens
Dis -cultures require an incubator set at 25-27°C which limits its use in the field
FAMACHA what is it, what nematode used for, when used and disadvantage
Haemonchus contortus ONLY
- measures levels of anaemia or blood loss (not faecal egg counts) and treatment decisions are based on these levels
- only when animals displaying clinical signs
Adv
- Decrease in the amount and frequency of treatment for the majority of the herd.
- Slows the development of anthelmintic resistance.
Dis
- Major issue is the cost associated with labour therefore not widely used in Australia
Pasture larval counts what does it estimate, advantages and disadvantages
Direct quantification from pasture
• estimate no of larvae/kg of herbage by collecting different samples from the paddocks
Dis
• slow
• does not detect low levels of contamination*
• non random distribution of larvae in paddock makes sampling difficult
Adv
• can be useful in comparing paddocks
Total worm counts how done and what can assess
Direct assessment from sacrificed animals (either very sick with high burden or introduce naive lamb to pasture and after 3-5 weeks slaughter)
- Can identify genera and species
In south-east Australia when is it most effective to treat and when is it ineffective
- Effective treatments in summer
○ 1st Nov - Dec -> all worms get in spring will kill
○ 2nd end of summer -> if picking up worms during summer
○ When move to low burden (due to paddock spelling, rotational grazing etc) pasture in winter time, will maintain low burden - If treat in mid-winter, L3 already on the pasture so treating the animal will kill the ones within the body but they will just get reinfected - INEFFECTIVE
List 6 ways to control trichostrongyloidosis
1) Paddock spelling - effective in summer to exposure to UV
2) rotational grazing - exposure larvae to heat and UV
3) crops - use of stubble - when feeding will decrease parasites
4) Alternative grazing - sheep and cattle alternating (not T. axei)
5) Anthelmintic drug - timing most effective 2 in summer
6) Smart grazing - merino weathers are the most susceptible to parasite infection
List the 8 steps in smart grazing
1) October select paddock to prepare for merino weathers in the winter of next year + select older animals
2) November bring in older animals to that paddock after treatment (deworming) using 2.5-3times the stocking density
○ Overgrazing paddock
3) December move older animals to another paddock
4) December to January don’t allow any animals to graze the pasture -> paddock spelling
5) February deworm the older animals again, and again bring to the same paddock for over grazing
6) After one month grazing in paddock move animals to another paddock
7) Throughout March and April leave the paddock -> paddock spelling
8) Throughout Winter graze the merino weaners on this paddock that now has a very low burden of worms
Hyostrongylus rubidus host, where found, lifecycle, PPP, clinical signs and control
Pig - stomach direct life cycle L3 in gastric glands PPP = 21 days causes diarrhoea, weight loss in piglets controlled on concrete floors
Ollulanus tricuspis host, where found, size, features, pathogenesis and transmission
Cat - stomach
- minute nematode (1 mm)
- female has a tail with 3-4 short cusps
- viviparous (L1-L3 develops within uterus)
- not very pathogenic
- L3 is transmitted in vomit - other cat that eat the vomit will become infected
Amidostomum anseris host, location, pathogenesis
(gizzard worm)
• ducks, geese, swans
• junction of gizzard & proventriculus
• larvae penetrate the thickened layer of gizzard lining
• highly pathogenic in large numbers
Trichostrongylus tenuis host, location, clinical signs, control
- found in caecum of galliform birds
- wide host range
- nodules & mortalities in galliform birds
- controls wild grouse populations -> help to maintain
Superfamiy Strongyloidea common name, location and PPP
strongyles Large intestine (rarely kidney or trachea) PPP varies as some species have extra-intestinal migration therefore pre-patent period becomes longer
Strongyloidea features, main hosts and larvae stages where present
Features • Medium to large • bursa in male • large well developed buccal capsule • leaf crown - finger like at the end of the buccal capsule ○ One or two rows Hosts - horses, ruminants, pigs, birds, elephants Life cycle L1 - L3 - faeces L3 - herbage L3 migrate - into intestinal gland L4 emerges - to lumen Final moult - in lumen
