Ruminants

• What are strongyles/strongylids?

  Clade 5 parasitic nematodes
• What is a characteristic of strongyle eggs?

  Many have similar looking eggs
• What does the prepatent period (PPP) refer to?

  The period from when an animal becomes infected to when it starts passing out eggs in its own feces
• What is hypobiosis in nematodes?

  A phenomenon where development is arrested at L3 or L4 stage within the host
• What factors can initiate the resumption of development in hypobiotic nematodes?

  Environmental conditions, genetic programming, host immune responses, and overcrowding
• Why is hypobiosis important for nematodes?

  It allows for survival in hostile environmental conditions
• What can result from the buildup of larvae due to hypobiosis?

  Serious outbreaks of disease
• How does the metabolic rate of arrested larvae affect their susceptibility to anthelmintics?

  It decreases, making them less susceptible to some anthelmintics
• What causes bovine ostertagiosis?

  Ostertagia ostertagi
• Where is bovine ostertagiosis distributed?

  Worldwide, mainly in temperate and subtropical climates
• Where do larvae of Ostertagia ostertagi develop?

  In the gastric glands of the abomasum
• Who is primarily affected by bovine ostertagiosis?

  Young cattle
• What is the PPP for Ostertagia ostertagi?

  3 weeks
• How long does it take for immunity to develop against Ostertagia ostertagi?

  Up to 2 grazing seasons
• When does Type 1 disease of bovine ostertagiosis occur?

  In calves during their first grazing season from mid-July
• What are the clinical signs of Type 1 disease?

  Profuse watery diarrhea, weight loss
• When does Type 2 disease of bovine ostertagiosis occur?

  In older calves (yearlings) in late winter/spring
• What is the mortality rate for Type 1 disease if treated early?

  Mortality is rare
• What are the clinical signs of Type 2 disease?

  Profuse diarrhea, anorexia, thirst, hypoalbuminemia, submandibular edema
• What happens to larvae during Type 2 disease?

  They undergo hypobiosis and emerge together in late winter
• What is the response to treatment for Type 2 disease?

  Poor response to treatment
• How much do larvae grow in gastric glands during pathogenesis?

  100 times
• What are the consequences of larvae growing in gastric glands?

  Erosion of secretory epithelium, swelling of gland, loss of secretory cells
• What does increased permeability of abomasal epithelium lead to?

  Leakage of pepsinogen into circulation and loss of plasma proteins to gut lumen
• What is the effect of loss of parietal cells in the abomasum?

  Decreased HCl and increased pH of abomasal contents
• What happens to protein digestion due to loss of peptic cells?

  Protein digestion is impaired
• What is the epidemiological effect of spring calving on ostertagiosis?

  Results in low levels of disease
• How do immune adults affect the transmission of ostertagiosis?

  They graze alongside calves and ingest larvae, leading to low egg production
• What happens to overwintered L3 larvae before suckling calves graze?

  They die before calves ingest much grass
• What is the effect of autumn/winter calving on ostertagiosis?

  It has higher levels of disease
• What occurs in the following grazing season if calves graze on contaminated pasture?

  Ostertagiosis occurs due to insufficient immunity
• Where do adults of Cooperia oncophora develop?

  On the surface of intestinal mucosa (small intestine)
• What are the clinical signs of Cooperia oncophora infection?

  Inappetence and poor weight gain in calves
• How long does it take for partial immunity to develop against Cooperia oncophora?

  After 1 grazing season
• How does the epidemiology of Cooperia oncophora compare to Ostertagia?

  It is similar
• What is Nematodirosis mainly caused by?

  Nematodirus battus in the UK
• Why is Nematodirosis important in lambs?

  It causes severe damage to the intestinal mucosa
• How does the development of Nematodirus battus occur?

  Development to L3 takes place within the eggshell
• What environmental conditions are required for hatching of Nematodirus battus?

  Prolonged chill followed by mean temperatures over 10 degrees C
• What happens to L3 larvae of Nematodirus battus after hatching?

  They penetrate the mucosa of the small intestine