Nematodes III: Ruminant Strongyles Flashcards
What is the general strongyle life cycle?
Eggs hatch (diagnostic stage) and L1 emerges in the envrionment
L1 goes through the 1st molt to become L2
L2 goes through the second molt to become L3, which is the parasitic stage
L3 migrates in the host and goes through the 3rd molt to become L4
L4 goes through the 4th molt and becomes adults
Adults copulate to produce eggs
What is periparturient rise?
Relaxation of immunity due to increases in prolactin
Rise in neamtode egg counts in the feces of lactating ewes or does at weaning
Describe Trichoctrongyles
Common High significance Primarily ruminants Few species in horses and swine Causes parasitic gastroenteritis
Describe parasitic gastroenteritis (PGE) diseases
Clinical disease in not as important as economic
Subclinical disease causes dramatic production losses
What causes arrested larval development (ALD) hypobiosis?
Larval development stops at a specific stage
They undergo no further growth and slow metabolic rate
What are the influencing factors of ALD?
Seasons
Climate
Host immune responses
Overcrowding effects in parasite population
How can you diagnose PGE?
History: grazing, parasites present, seasonal occurrence, management
Clinical signs: pathology, fecal egg counts
What is the treatment and control of PGE?
Consider the epidemiology of the parasites being targeted ---Biology of parasite populations ---Climate ---Pasture and animal management Properties of the drug being used
What is a huge problem in small ruminant strongyles?
Anthelmintic resistance
How can you detect anthelmintic resistance?
Fecal egg count reduction test
Larval develpment assays
What is refuge?
Susceptible parasite gene pool not exposed to a particular control measure (escapes selection for resistance)
What are methods of integrated pest management?
Fecal egg count Pasture rest/rotation Multi-species grazing Increase grazing height Reducing stocking rates Resistance breed selection
What is FAMACHA test?
Anemia guide that monitors fecal egg counts in small ruminants, especially Haemonchus contortus
What is the host of Ostertagia ostertagi?
Cattle
What is the site of Ostertagia ostertagi adults?
Abomasum
Describe Ostertagia Ostertagi L3
Burrow into gastric glands in pyloric and fundic regions
Molt 2 more times
Emerges as immature adults
What is the life cycle of Ostertagia ostertagi?
Eggs in feces (diagnostic stage) L1 --> L2 --> L3 (infective stage) L3 burrow gastric glands in pyloric/fundic regions L4 ALD abomasal glands Emerge as immature adults Adults; no feeding
What is Ostertagia ostertagi pathology?
PPP: 18-21 days
Can arrest as early L4 stage in abomasal glands
What is type I ostertagiosis?
Occurs when recently ingested L3 develop to adulthood without ALD
What does type I ostertagiosis affect?
Young cattle grazing pastures for the first time
What is type II ostertagiosis?
Occurs when arrested larvae synchronously resume development; synchronous emergence from glands weeks or months after infective L3 are ingested
What does type II ostertagiosis affect?
Animals 2-4 years of age
What are the clinical signs of ostertagiosis?
Diarrhea
Weight loss/emaciation
Dehydration/thirst
Hypoproteinemia/submandular edema
What is the host of Teladorsagia (Ostertagia) circumcincta?
Sheep and goats
