Dictyocaulus Flashcards
What is the common name for the dictyocaulus viviparus?
Cattle lungworm it is a trichostrongyle lungworm
What species and age does dictyocaulus viviparus infect?
Cattle- dairy replacement heifer calves
What species does dictyocaulus filaria infect?
Sheep and goats- highly pathogenic, occurs in UK
What species does dictyocaulus arnfieldi infect?
Horses and Donkeys
Respiratory dieases in horses
Patent infection in donkeys
Horses are source of infections
What disease does dictyocaulus viviparus cause and where is it more commonly found?
Parasitic bronchitis- ‘husk’ or dictyocauliosis
More common in the wetter west of the UK
Describe the morphology of adult dictyocaulus viviparus?
4 to 8cm
Slender white
Male has reduced bursa
Where are the adult nematodes found?
Trachea and Bronchi
Describe the life cycle of the dictyocaulaus
- Direct- only 1 host
- Female worms are ‘ovo-viviparous’- larvated eggs which hatch immediately
- L1 in the lung (URT)
- Coughed up, swallowed and passed out in faeces
- L1 to L2 to L3- don’t feed
- L3 ingested- lympho-tracheal migration
- L3 moults to L4 in lymph nodes
- L4 to L5 in lungs
- L5 migrate up bronchial tree
- Adults in bronchi and trachea
- Adults lay eggs which hatch into L1
What are the different stages of dictyocaulus?
How long into the life cycle do they occur?
Outside the host- L1-L3- 5-7 days
Penetration phase (L3 to L4 to lungs)- 0-7 days
Pre-patent phase (L4 to L5, L5 to URT)- 8-25 days
Patent phase- (adults lay eggs)- 26-55 days
Post-patent phase- 55 days+
How long does is take D.viviparous to go from L1-L3?
5-7 days in optimal conditions
What stage of the life cycle is this D.viviparous?
L1
Refractile food granules
What are the most pathogenic stages of the d.viviparous life cycle?
Pre-patent and patent phases
Pre-patent- L4/5 in lungs
Patent- adult worms in upper respiratory tract
Describe the pathology and clinical signs of the pre-patent phase of D.viviparous
- Intense inflammatory response
- Alveolitis, bronchiolitis, bronchitis
- Interstitial emphysema
- Pulmonary oedema
- Coughing, respiratory distress, tachypnoea, weight loss
Describe the pathology and clinical signs of the patent phase of D.viviparous
- Mature adults in bronchi/trachea
- Eggs and L1 swept into alveoli
- Intense inflammatory response
- Frothy white mucous
- Emphysema, hypoxia
- Gasping, coughing, death
Describe the pathology and clinical signs of the post-patent phase of D.viviparous
- Resolution of clinical signs
- In some animals epithelialisation of lung tissue causes them to never recover
What factors affect pre-parasitic stages of D.viviparous?
Temperature
Moisture
Dispersal of L3- pilobolous fungi
Epidemiology unpredictable
L3 can overwinter on the pasture
L1 shed by carrier animals
What is this an image of?
Pilobolus fungi with L3 larvae attached which ‘explodes’ and disperses the L3
When does disease of D.viviparous occur and what animals are usually affected?
Usually in August- september can be till Nov
Usually in dairy replacment calf
How many worms are needed to cause disease from D.viviparous?
few 800-1000 worms
Can take few weeks/cycles after turnout
How is D.viviparous diagnosed?
Clinical signs
L1 in faeces using at Baermann
Antibody detection ELISA
How is D.viviparous treated?
Rapid use of anthelmintics- MLs first choice no current resistance
NSAIDs, antibiotics
TLC- house most severly affected calves
How is D.viviparous controlled?
Anthelmintic prophylaxis- covers GI nematodes, but no immunity builds up, adults at risk
Increasing numbers of outbreaks of dictyocauliosis in adult cattle reported- reduction in milk yield, overt clinical disease
Vaccine- Huskvac
- Live attenuated vaccine- 1000 irradiated L3
- Given orally
- Two doses
- Four weeks apart
- Before turnout
- requires natural boosting to maintain immunity
You find an L1 in sheep faeces, what species of nematode could it be?
Dictyocaulus filariae or Muellerius capillaris
Why are donkeys with Dictyocoulus arnfeldi advise to be grazed seperatley to horses for control?
Donkeys are asymptomatic carriers of D.arnfieldi and a source infection in horses
How would you isolate and identify L1 of D.viviparous in cattle?
Use a Baermann apparatus to isolate the larvae, they are the only L1 found in faeces of cattle
What is the infective stage and PPP of D.viviparous?
Infective is L3
25 days PPP
What does the term ovo-viviparous mean?
When eggs passed by the female worm are already larvated and hatch immediatley when layed
How would you diagnose dictyocaulisosis in (a) first season grazing calves and (b) adult milking cows?
- (a) calves show clinical signs (coughing, weight loss, dyspnea), confirm by detecting L1 in faeces
- (b) adult milking cows usually show drop in milk yield, then may show clinical signs, confirm with Baermann
Why is Dictyocaulisosis an unpredictable disease?
Fewer larvae required to cause disease- dont need build up on pasture
L3 can overwinter and can be blown onto clean pasture
If a dairy farm has an outbreak of dictyocaulus in milking cows what would you advise?
Cattle havent built up immunity- therefore vaccinate FSG cvalves before turnout to develop immunity, quarantine bought animals to prevent introduction and monitor antibody levels
