Lung Worms Flashcards
What are the general characteristics of metastrongyles?
- Lungs or related blood vessels
- Normally L1 in faeces
- L1 have typically ‘kinky’ tails
- Normally indirect life cycles with mollusc intermediate hosts (snails and slugs)
- Lympho-tracheal migration
What are the lung worms of dogs?
Angiostrongylus vasorum (heart worms of dogs)
Oslerus osleri
Crenosoma vulpis, Filarroides hirthi
What is the lungworm in cats?
Aeurostrongylus abstrusus
Where are the following metastrongyle nematodes found:
Metastrongylus apri
Muellerius capillaris
Metastronglylus apri- Pigs
Muellerius capillaris- Sheep
What parasite is this (aka the french heartworm)
Where is it found?
How long is it?
Whst are its intermediate and paratenic hosts?
Angiostrongylus vasorum
Adult worms are found in the pulmonary artery and right ventricle
2cm long
Intermediate host- slugs and snails
Paratenic host- frogs
Describe the lifecycle of the angiostrongylus vasorum life cycle
What is the pre-patent period?
- Adults in blood vessels associated with the hear- pulmonary artery
- Eggs are released into the blood stream and reach the capillary beds of the lungs and hatch into L1 larvae
- They move across into alveolus and are transported up the airway into larynx and swallowed- pass into faeces into environnment
- Slugs and snails act as intermediate hosts, ingesting L1 larvae which undergo two moults to become infective L3 larvae- temp dependent
- Frogs can act as paratenic hosts
- Fox is natural gosts and helps spread disease
- Ingested L3 larvae from slugs cross the intestinal wall and mature to L4 and L5 within the abdominal lymph node
- Migration continues via the liver and caudal vena cava to the right ventricle and pulmonary artery
Pre-patent period is 5-8 weeks
What are the clinical signs of angiostrongylus vasorum?
Often asymptomatic but can cause sudden death
Respiratory
- Coughing
- Dyspnoea
- Weight loss
- Pulmonary hypertension
Coagulopathies
- Fluctuating haematoma/bleeding disorders
Neurological
How can angiostronglyus vasorum be diagnosed?
Antigen SNAP test
Radiograpghy-
Enlarged heart and pulmonary artery
Pathcy alveolar and intersitial pattern
Differentiate from other lung worms
L1 in faeces, trans-tracheal wash or bronchoalveolar lavage
- ‘Dorsal notch’ on the tail of the L1
- 300 to 400um
- Baermann apparatus to detect L1- low sensitivity, repeat samples
How is angiostrongylus vasorum treated and controled?
Treatment:
Moxidectin
Milbemycin oxime
Fenbendazole
Control:
Corticosteroids
Cage rest during treatment (2-3 days)
Prophylaxis- monthly treatmenr with macrocylic lactones
When possible prevent from ingesting snails or slugs
What affects the epidemiology of angiostrongylus vasorum?
Changing epidemiology and prevalence of canine angiostrongylosis
Historically the foci of infection was in South West England and South Wales
Infection extending north and east, now prevalent in Scotland
Foxes are reservoir hosts-
Effect of climate on slug/snail population
Describe the life cycle of oslerus osleri
What is the peri-patent period?
Direct life cygle
Adult in nodules in trachea
Females are ovoviviparous
L1 are passed by the female
L1 are released into tracheal lumen and move up pharynx and swallowed and passed into faeces
Infection of the definitive host is ingestion of L1 larvae- transmission mainly by the bitch grooming and licking pup
Upon ingestion/introduction into the mouth, L1 cross the intestinal wall, travel via the lymphactics and blood stream to the lungs and trachea
PPP- 10-18 weeks
How is oslerus olseri diagnosed and treated?
How does the disease present?
Diagnosis:
- Young dogs 1-2 years
- Bronchoscopy to identify nodules
- Larvae in faces- low sensitivity
- Transtracheal wash or broncheoalveolar lavage cytology or tracheal swabs may reveal larvae or eggs
Treatment- fenbendazole
Disease- tracheo-bronchitis, coughing
Describe the Aelurostronglus abstrusus life cycle
Adults in lung parenchyma
L1 in faeces
Snail intermediate host
Paratenic hosts- small mammals, frog, lizard
PPP 5-6 weeks
How can aelurostrongylus abstrusus adults and L1 be distinguished from other lung worms?
Adults in lung parenchyma- very small- 10mm
L1 in faces have and S shaped tail
What are the clinical signs of aelurostrongylus abstrusus disease?
How is is diagnosed?
How is it treated?
Disease:
- Normally asymptomatic
- Common- 7%
- Hyperplasia of the bronchioles, alveolar ducts and pulmonary arteries
Diagnosis:
L1 in faces- baermann technique- fresh faecal samples
L1 in transtracheal wash or bronchoalveolar lavage
Treatment:
Fenbendazole- for at least 3 days
Moxidectin, Emodepside
