Parasitology 2/3: Nematodes 1&2 Flashcards
Helminths have a few routes or a lot routes?
Many routes
-Ingestion of infective stage
-ingestion of paratenic/intermediate host
-maternal
-skin penetration
-arthropod-borne
ALL helminths are what kind of parasites?
hint*-parasites
MACROparasite
do NOT multiply in host
Describe Helminths?
cellular?
host?
repro outcomes?
life cycle?
transmission?
Complex and multicellular
some are host specific definitive but not always
Repro products of adults are eggs (OVIPAROUS) or larvae (OVOVIVIPAROUS)
Commonly have DIRECT life cycle
environmental-oral ( better way to describe than fecal-oral because many animals don’t eat direct feces)
Helminths breaks into which 2 groups?
Nematoda
Platyhelminthes
Nematoda
Word meaning?
Location?
Organisms?
Size?
Shape??
Thread
non-segmented, cylindrical, generally tapered at both ends
most successful of all the worms
many free living soil nematodes
major plant and animal parasite species
Range in size from micrometer to meters
Skin/outer surface of Nematodas?
Cuticle
-flexible, but NOT metabolically active
-many shapes
— spines, ridges, secondary sexual structures
Nematodes inside body descriptions?
Fluid filled body cavity
intestine and repro system are suspended in cavity
body wall has a muscle layer provides movement
lots of structures for sensing the environmnet
neurotransmitters:
-Ach**
-GABA
Nematoda digestive system
Food depends on species and location in host
oral opening: buccal capsule (cavity)
Esophagus (pharynx)
Intestine
Nematoda repro system
females and males
generally separate sexes
females usually bigger than males
Males have 2nd structures: spicules (* for repro)
females produce eggs or larvae
Development of nematodes occurs by?
Cuticle restricts growth
all nematodes go through 4 molts
stages in between molts referred as to L1, L2, L3, L4, and adults
L3 rule: stage is infective for definitive host UNTIL L3
What stage is infective when talking about Nematodes?
L3
Strongylida superfamily has how many ?
4
What is a difference between a male and female strongylidas?
Males have a Bursa (spicules) and smaller
what is the pathogenic mechanism in Strongylida?
damage from tissue- phase of development
blood or tissue feeding
inflamm/immune response-affected GI function
anorexia- multifactorial
What kind of life cycle do MOST strongylida have?
Direct
Describe strongylida eggs?
smooth/thin shell
have morula
can NOT be differentiated
diagnosis: fecal flotation
Describe the general life cycle for MOST of strongylida?
- eggs voided in feces
-L1 hatch and develop L 3 (2 molts)
-L3 retains cuticle of L2 as protective sheath (ensheathed L3): climb grass
-L3 ingested by host: INFECTIVE STAGE
-Larvae travel to predilection site and develop to adults
How do strongylida survive when living outside of host?
They use reserves from L1 and L2 for energy
L2 sheath to travel through the environment
How are parasites able to move around after being excreted in feces?
- after being excreted from animals the manure then it must escape manure
-the parasite want to go towards water, warmer surface, and go towards sunlight relative amount of all these tropisms
It uses the sheath from L2 to protect itself & go about in the environment
Hypobiosis means what?
arrested or inhibited development
ONLY occurs INSIDE the host
What are the RELATIVE tropisms?
Hydro +
Thermo +
Geo -
Photo +
Characteristics of L3 ?
Sheathed by L2
Energy reserves for L1 and L2
The tropisms
Hypobiosis can occur in different larval stage; what are some examples?
L3-
Trichostrongylus
Anceylostoma
Cyathostominae
L4-
Ostertagia
Teladorsagia
Haemonchus
What is the most common stimuli for arrested development?
Environmental
What is the other (not most common) stimuli for arrested development?
Host immunity
Is the immunity development for Strongylida aggressively fast or gradual?
Gradual
Immunological compromise can shift balance in favor of a parasite and allow numbers to increase. Examples are:
Parturition (“ Periparturient egg-rise”)
Malnutrition
Concurrent
Why is Parturition and important immunological compromise?
Periparturient egg rise
Makes more eggs and plays a big part in parasitic and disease control
What does large numbers of parasite mean?
Animals have clinical signs
Trichostrongyloidea is present in what species?
RUMINANTS
What life stage are trichostrongylidea infective?
L3
they develop and survive in weeks to months depending on weather
Is Hypobiosis common or rare in Trichostrongyloidea?
Common hypobiosis
which ruminants have Trichostrongyle parasites?
ALL grazing ruminants
Which Trichostrongyloidea are we talking about and what species do they effect?
Ostertagia/Teladorsagia: Cattle
Haemonchus contortus: Sheep/Goat
*OCCURS IN ABOMASUM
What do the all the Trichostrongyloidea together cause thats important (except Haemonchus)?
Parasitic Gastroenteritis (PGE)
-diarrhea
-weight loss
What is the best indication you are seeing a Haemonchus parasite?
ANEMIA
What is the common name of OStertagia?
Brown stomach worm
What is the common name of the Haemonchus c?
Barbers pole worm
Ostertagia most pathogenic changes are?
L4 emerging of the abomasa mucosa – in GASTRIC GLAND to lumen
NODULES
Are Ostertagia adults very pathogenic?
False
When you have hypobiosis is the infection worse or better?
it will be WORSE
because instead of having maybe 3 parasites emerging; you can have 100 emerging all together at the same time (they come out at at ideal ENVIRONMENT)
Tell importance of L3 and L4 when talking about Ostertagia?
L3: is the infective stage
L4: is when the larvae are emerging
Ostertagia impact of larvae on gastric glands cause what?
Cell diff
Hyperplasia
formation of NODULES
What other impact does Ostertagia larvae have?
Theres a failure to activate pepsinogen due to higher pH and then that causes failure to activate pepsin
This low pH causes pepsinogen to build up and spill into blood (leakage)
This then causes loss of plasma proteins
What is the clinical importance of Ostertagia?
Pathological stage is L4
young and immune comp animals cause
diarrhea
weight loss
hypoproteinemia: bottle jaw
Death in weeks
Haemonchus affects which ruminants?
Small ruminants
Are Haemonchus contortus infectious as larvae or adults?
ADULTS
Why is Haemonchus more pathogenic than most other trichostrongyles why?
blood feeding
Why is Haemonchus the most important helminth in small ruminants?
They are a global problem
What is the clinical importance of Haemonchus?
Heavy infections
–anemia, NOT diarrhea, anorexia, bottle jaw, weight loss, death
-fatal infect: can remove 1/5 of circulating blood volume per day
-nonfatal infect: 1/10 in a 2 month period
Type 1 disease for Trichostrongyloidea is described as?
cause larvae daily and continuously
represent accum. of adult worms during grazing season
usually in late summer or autumn, in you animals in pasture
any sheep/goat with anemia in the grazing season has haemonchosis till proven otherwise
Type 2 Trichostrongyloidea disease is described as?
Happens AFTER larvae that has been arrest resume their life cycle
synch emergence of arrested larvae
It occurs in late-winter or spring, more common on Ostertagia
Can produce severe fatal disease due to severe abomasal disease or anemia
