Ruminant Strongyles Flashcards
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!!
Ostertagiosis - clinical signs
- diarrhea
- weight loss/emaciation
- dehydration/thirst
- hypoproteinemia/submandibular edema
Teladorsagia circumcincta
Sheep and goats (same as O. ostertagi, just different host)
- abomasum
- contributor to PGE
- diarrhea, poor weight gain/weight loss
- cool dry conditions
Haemonchus - life cycle
Eggs in feces (diagnostic) –> L1 –> L2 –> L3 (infective) –> L3 exsheath in rumen –> L3 move to abomasum, near glands –> L4 ALD, emerge immature adults, blood feeders –> molt to adults, blood feeders!!
Haemonchus classification
Family: Trichostrongylidae
- H contortus: sheep, goats
- H placei: cattle
Haemonchus - L3 stage
Pasture L3 are not resistant to cold!
- exsheath in rumen
- move to abomasum near glands
- molt 2 more times
- emerge as immature adults
- blood feeders!
- can arrest
Haemonchosis - clinical signs
Hyperacute, acute, chronic
- anemia
- skin pallor
- pale mucous membranes
- hypoproteinemia and edema (bottle jaw)
- dark feces
- death
- blood feeders as adults and L4s
Trichostrongylus spp.
Family: Trichostrongylidae
- T. axei: abomasum in ruminants, stomach in horses
- T. colubriformis: SI in ruminants
- asymptomatic, contributor to PGE; ALD
- massive infections = black scours
Which is larger among Trichostrongylus, Ostertagia, or Haemonchus?
Haemonchus
Cooperia classification
Family: Trichostrongylidae Cattle - C. onchophora - C. punctata - C. pectinata Cattle and sheep - C. sumabada Sheep and goats - C. curticei
Cooperiosis
Small intestine, can arrest (ALD)
- secondary pathogens
- weight loss/poor weight gain
- diarrhea
Oesophagostomum classification
Family: Chabertiidae
Cattle: Oesophagostomum radiatum
Sheep and goats: O. columbianum
Morphology of Oesophagostomum radiatum
Cuticular modifications at the anterior end
- cephalic vesicle
- cervical vesicle
- cervical alae
Oesophagostomum - life cycle
Eggs in feces –> L1 –> L2 –> L3 (infective) –> L3 exsheath in SI mucosa; form nodules –> emerge from tissue to lumen as L4 –> L4 move to colon/cecum; emerge as adults
Oesophagostomum pathology
- hemorrhagic or purulent nodules
- mucus
- leakage of blood and plasma proteins
- contributes to PGE: inappetence, weight loss, anemia, diarrhea
Diagnosis of ruminant strongyles
- culture and identify L3
- identify adults at necropsy
- strongyle type eggs
- fecal float: ellipsoid, thick shelled, greyish
Nematodirus classification
Family: Molineidae Cattle: N. helvetianus Sheep: - N. battus - N. filicolis - N. spathiger Found in temperate regions
Nematodirus spp
Pasture larvae - resistant to drying/freezing Eggs - very large Adults - cephalic vesicle: bulbous swelling of cuticle at tip of anterior end
Nematodirus - life cycle
Eggs in feces (diagnostic) –> larvae mature (L1-L3 in egg) –> hatch, extrinsic stimuli –> L3 (infective) –> L3 ingested, penetrate SI mucosa –>L3 –> L4 –> L4 enter lumen of SI –> molt to adults in SI
Nematodirus diagnosis
- fecal float
- eggs: larger than typical “strongyle type”
- ovoid to football shaped
What are the most important/least important cattle strongyles?
Most important - *Ostertagia ostertagi* - Cooperia - Haemonchus placei - Trichostrongylus axei Less important - Oesophagostomum - Nematodirus
What are the most important/least important small ruminant strongyles?
Most important - *Haemonchus contortus* - Trichostrongylus colubriformis - Teladorsagia circumcinta - Trichostrongylus axei Less important - Cooperia - Oesophagostomum - Nematodirus
Strategies for managing Haemonchus contortus
- specialized behaviors of goats
- prefer to browse a variety of plants
- accompanying physiological adaptations to consumption of secondary compounds contained in browse
- browsing behavior
- pasture management
- bioactive forages
- identifying and treating individual animals
