Lecture 6 and 7 Flashcards
(51 cards)
1
Q
What is a common parasite in grazing ruminants
A
Gastrointestinal stongylosis
2
Q
What does the pathogenesis of Gastrointestinal stongylosis depend on
A
Climatic change, age of host, season
3
Q
In Gastrointestinal stongylosis, what are the production losses because of
A
- Visable clinical signs: anaemia, diarrhoea, anorexia
- Less visible clinical signs: decresased weight gain, decreased milk yield, decreased fertility, increased prodctuion
4
Q
What is a big problem with Gastrointestinal stongylosis
A
- Chemoresistance
5
Q
What are the important Gastrointestinal stongylosis in sheep and goats
A
- Haemonchus contortus
- Trichostrongylus
- Teladorsagia/Ostertagia circumcincta
6
Q
What are the important Gastrointestinal stongylosis in Cattle
A
- Ostertagia ostertagi
- Trichostrongylus axei
- Cooperia oncophora
*
7
Q
What is the lifecycle for Gastrointestinal stongylosis
A
- Generally simialr for all species
- Developmet of larvae (L1-L3) develop in faeces
- L3 - infective stage
- Retain the cuticle/sheath of L2 -> confer resisyance
- Leave the faeces -> moves on the grass to be ingested by host
- L3 are more resistant than the previous stages to desiccation and extreme temperatures
8
Q
What climate factors play and important
A
Temperature and humidity
9
Q
A
10
Q
What are the free living stages divided into
A
- Development of the egg ot L3
- Survival and infection/death of L3
- L3 survive best with lower temperature and high mositure
11
Q
What is important with L3
A
Rain - leave faeces and move on to the pasture. RAIN isn NB to break down the faeces
12
Q
When does arrested development happen
A
Early L4 - remain dormant for several months
13
Q
What does the success of a parasite depend on
A
- Resistance/persistence. of larve on the pasture
- Persistence of worms within the host when external conditions are unsuitable for survival
14
Q
What is the epidemiology of GI strongylosis
A
- Almost all ruminants that are grazing are infected with GIS but their effects on the heapth and productions of the host depends on the levelof infection
- Effects of weather and pasture conditions on the developmet and survival of the larvae -> the abundance of the larvae on the pasture when to drench, when to graze
- The development and the survival of parasites in the host, hypobiosis and the egg production
- Effects of changes inhost resistance
15
Q
Explain the epidemiology triangle
A
- Environemnt
- Host
- Parasite
16
Q
What is resilience
A
- The ability of animlas to maintain acceptable measures of productivity in spite of habouring ‘normal’ levels of parasites
17
Q
Explain Resistance
A
The ability of animals to reduce their parasitic burden, either by preventing larval establishment or by removing established worms more quickly
18
Q
Explain the differences between sheep and cattle worms
A
19
Q
What are the factors that affect worm population
A
20
Q
Explain the distribution of GIS in Australia
A
- Effect of environmental factors on the free living stages of pasture will determine
- Geographical and temporal distribution
- Common and significant in higher and uniform rainfall areas
- Geographical and temporal distribution
21
Q
What does susceptibility depend on
A
- Age
- Genetic factors
- Condition of the host
- Nutrition
22
Q
Source of contamination
A
- Infected animals: pass in their faeces
- Young animals are generally heavily infected and deposit large number of eggs
- Adult animals properly fed might deposit a small number of eggs
- Number of eggs deposited depends on
- Species of parasite
- Immune response
- Season
23
Q
What are the sources of larvae on pasture in spring
A
- Carryover L3
- Lactating ewes are the contaminator of pasture
- Lamb-at-foot most susceptible
- Weaners very susceptible
24
Q
How are host infected with GI strongylosis
A
- Orally by L3 from pasture
25
Factors that favour GI strongylosis infection
* Season/weather
* Crowding
* Nutrition
* Introduction of young/naive animals on heavily infested pastures
26
What parasite is this
Haemonchus contortus
Barber's pole worm
27
What is the most important endoparasite of sheep and goats in summer tainfall areas
* Harmonchus contortus
* Huge population develop in a short amount of time when conditons are favorable
28
What is the morphology of haemonchus contortus
* Females look like barber's pole
* Anterior end: small mouth with tooth
* Posterior end: convered by a prominent flap that is tongue shaped (female), large bursa has larger lateral lobes and small asymmertrical dorsal lobe - dorsal ray is Y shaped (male)
29
What is this egg from
Haemonchus contortus
30
What is the epidemiology of haemonchus contortus
* Predominant in summer rainfall areas: increase in spring, maximum in Feb then decline
31
What is the optimum temp for haemonchus contortus developemt
* 25-35 degrees
* Larve don't develop at temperatures lower than 10 degrees
32
What do the larval stages of haemonchus contortus have low resistance to
* Dehydration
* Low temperatures
* (like warm, moist summers)
33
What are the pathogenic stages of haemonchus contortus
L4 and adults
34
How do haemonchus contortus feed
* Parasites make cutting movement at host tissues with its tooth and feeds on the released blood, cell contents and fluid
* Blood sucking begins at L4
35
Why do sheep get bottle jaw with haemonchus contortus
* Loss of serum proteins -\> decrease of osmotic pressure -\> bottle jaw
36
Effects of haemonchus contortus
* Anaemia
* Abomasal content is usally fluid and dark red-brown, because of presence of blood
* Abomasal folds are edematous with focal areas of hemorrhage on the surface
* Hypoproteinaemia
* Reduced excercise tolerance, weakness -\> leg behind the mob, refuse to move -\> fall behind
37
What is the epidemiology of haemonchus placei
* Common in summer rainfall areas of NSW, QLD, NT and kimberly region of WA
* Infections are common in summer and autumn
38
What are the clinical signs of haemonchus placei
* Dairy calves (4-12 months), beef calves during the first year after weaning
* Anaemia, hypoproteinemia -\> submandibular oedema
* Weakness, weightloss, unthriftiness
39
What parasite does this
haemonchus placei
40
What parasite causes this
Ostertagia/Teladorsagia
41
What aninals does Ostertagia ostertagi affect
Cattle
42
What animal does Teladorsagia circumcincta affect
* Sheep and goats
43
What is the lifecycle of Ostertagia
* Female worm can produce 100-200 eggs daily
* Larave development takes place between 5-35 degrees
44
How are cattle infected with Ostertagia
Ingeted L3
* Enter glands in the abomasum where they elict nodules and swelling -\> L4 that either emerge to lumen and continue development or may arrest early L4
45
What is the pathology of Ostertagia
* Associated with the emeregence of the worm from gastric glands/nodules
* Hyperplasia of cells producing mucus - umbilicated nodules
* Pale nodules with depressed centre
* Hyperaemia, oedema
* Reduction of gastric secretion -\> increase in abomasal pH
* The cell junction between epithelial cells are altered
* Enhanced permeability of the bowel wall to amrcomolecules
* Increase in blood pepsinogen and gastrin levels
* Hypoalbuminemia
* Energence of the worms from the glands is followed by necrosis and sloughing of the surfcae epithelial cells -\> dipteric membranes
46
What are the clinical sings of Ostertagiosis type I
* Due to acquisition of large number of L3 and direct development of large number of adults over a relatively short period of time
* Seen in animals on pasture 3-4 weeks after the availability of large number of infective larvage
* Anorexia, watery diarrhoea, rapid weight loss
*
47
What are the clincial signs of Type II Ostertagiosis
* Due to the synchronous matureation and emergence of large numbers of hypobiotic larvae from the mucosa
* Occurs in older animals
* It may occur when the intake of larvae is low or nonexistent
* Rapid onset; it affects only a number of cattle in a herd
48
What is Teladorsagia
* Mainly a problem in young sheep and contributes to weaner ill-thrift
* Main signs are scouring, loss of condition, anorexia and death
* On necropsy raised pin-point white foci in the abomasal mucosa
49
What is shown
Trichostrongylus
50
What is the morphology of Trichostrongylus
* Small
* Excretory pore in sonspicuous ventral notch
* Male: the spicules are short, brown, stout, ridged
* Female may deposit 100-200 eggs/day
* Optimal temperature 25 degrees
* Perpatent period 15-21 days
51
What are the clincal features with Trichostrongylus
* Pathology associated with thousands of parasites
* Anorexia, decreases in weight gain, dark-coloured diarrhoea
* Villus atrophy, erosions, leakage of plasma proteins into the lumen
