Ruminant Strongyles Flashcards
(46 cards)
Ruminant strongyle classification
Phylum: Nematoda Order: Strongylida Superfamily: Trichostrongyloidea Family: Trichostrongylidae - Ostertagia - Haemonchus - Trichostrongyles - Cooperia Family: Molineidae - Nematodirus Superfamily: Strongyloidea Family: Chabertiidae - Oesophagostomum
General Strongyle life cycle
DH has PPP of 2-4 weeks
- diagnostic stage: eggs, hatch; L1 emerges –> environment –> 1st molt –> L2 –> 2nd molt –> L3 (parasitic stage) –> 3rd molt –> migration in host –> L4 (4th molt) –> adults –> copulation
Periparturient rise
Relaxation of immunity due to increases in prolactin
- rise in nematode egg counts in the feces of lactating ewes or does at weaning
Which species of Trichostrongylidae has the longest PPP?
Haemonchus placei
- 23-32 days
Which species of Trichostrongylidae only infects horses?
Haemonchus axei
What species of Chabertiidae has the longest PPP?
Oesophagostomum radiatum
- 28-41 days
What species of ruminant strongyles lives in the large intestine?
Oesophagostomum radiatum
Trichostrongyles
Common, high significance
- primarily ruminants
- few species in horses and swine
- parasitic gastroenteritis (PGE) = any GIT problem due to parasites, common name
Parasitic gastroenteritis
Subclinical disease has dramatic production losses
- significant weight loss
- diarrhea (watery, green)
- loss of appetite
- high proportion of animals affected
- dehydration
- rough hair coat
- submandibular edema
- pale mucous membranes
Arrested larval development (ALD)
Hypobiosis
- larval development stops at a specific stage –> undergo no further growth
- slow metabolic rate
Influencing factors of hypobiosis
- seasons
- climate
- host immune responses
- overcrowding effects in parasite population
Diagnosis of PGE
History: grazing, parasites present, seasonal occurrence
Clinical signs: pathology, fecal egg counts
Control of PGE
Consider epidemiology of parasites being targeted
- biology of parasite populations
- climate
- pasture management
- animal management
- properties of drug being used
Anthelmintic resistance
FDA-approved antiparasitic drugs for sheep and goats
- huge problem in small ruminant strongyles, emerging problem in cattle
- detection: fecal egg count reduction test, larval development assays
- FAMACHA test for anemia
Refuge
Susceptible parasite gene pool not exposed to a particular control measure (escapes selection for resistance)
- pasture
- untreated animals
- inhibited larvae
Integrated pest management
- fecal egg count: eggs per gram
- pasture rest/rotation
- multi-species grazing
- increasing grazing height
- reducing stocking rates
- resistant breed selection
FAMACHA test
Anemia guide
- allows for fewer anthelmintic treatments
- monitor fecal egg counts (over dispersal of parasites)
- done in small ruminants, especially for Haemonchus contortus
- deworm on individual basis instead of the whole herd
Ostertagia ostertagi
Most important one in cattle!!
- site of adults: abomasum
- PPP: 18-21 days
- family: Trichostrongylidae
Ostertagia ostertagi - L3 stage
Burrow into gastric glands in pyloric and fundic regions
- molts 2 more times
- emerges as immature adults
Ostertagia ostertagi - life cycle
Adults; no feeding –> eggs in feces (diagnostic stage) –> L1 –> L2 –> L3 (infective stage) –> L3 burrow gastric glands, pyloric/fundic regions –> L4 ALD abomasal glands –> emerge as immature adults
Ostertagia ostertagi - pathology
PPP: 18-21 days
- can arrest as early L4 stage in abomasal glands
Ostertagiosis
Type 1
- occurs when recently ingested L3 develop to adulthood without ALD
- young cattle grazing pasture for first time
Type 2
- when arrested larvae synchronously resume development, synchronous emergence from glands weeks or months after infective L3 are ingested
- animals 2-4 years of age
Ostertagia commonly arrest when it is ______
Hot outside (March-September) for southern states = large number of adults in fall October - March in Northern states = large number of adults in summer
Ostertagia pathology is associated with _______
Larval growth and development
- NOT feeding behavior!!