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44 Cards in this Set

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What are the features of metastrongyles?
Adults are in respiratory, vascular or nervous systems.

Males usually have a bursa but it is often reduced or absent and the spicules are highly variable in size and shape.

Females are oviparous or ovoviviparous, but L1 or egg with L1 shed in feces

No buccal cavity; small mouth

INDIRECT life cycle with gastropod IH
What lung worms are present in each species?
Small ruminant lungworms: Protostrongylus and Muellerius

Swine lungworm: Metastrongylus spp.

Oslerus osleri - tracheal worm
Filaroides spp and Crenosoma - lungworms

Feline lungworms: Aleurostrongylus

Cervids: Parelaphostrongylus tenuis - meningeal worm
What are the lungworms of ruminants?
1. Superfamily Trichostrongyloidea: Dictyocaulus spp
Largest lungworm in upper airways
(in cattle, small ruminants, cervids, camelids)

2. Superfamily Metastrongyloidea: Protostrongylus spp - smaller; in bronchioles, alveoli and parenchyma
Muellerius - hair lungworm; smallest: in alveoli
(both in small ruminants, not in cattle)
Indirect life cycle of Protostrongylids (Protostrongylus and Muellerius)
L1 in fresh feces --> L1 infects intermediate host (snails and slugs) --> Develops to L3 in intermediate host --> Infection acquired by ingesting IH
Describe Protostrongylus spp.
1. Adults: in bronchioles, alveoli, lung parenchyma; approximately 2-4 cm long
2. Prepatent period: ~ 1 month
3. Patent period: 2 years
4. Transplacental transmission of larvae of fetal liver: after birth, larvae migrate from liver to lung
Define Protostrongylus rufescens.
Red lung worm
1. Domestic small ruminants
2. Adults reddish-brown when fresh
3. Males 16-28 mm long
4. Females 25 - 35 mm long
What are the lesions and signs of Protostrongylus spp?
1. Local inflammation + exudate in lung tissue distal to adults in bronchioles

2. Desquamation of epithelium (alveoli, bronchioles): occlusion of blood vessels and CT proliferation

3. Result: lobular pneumonia: conical yellow-grey, possible localized fibrinous pleuritis

4. Usually sub-clinical
What is the diagnosis of Protostrongylus?
1. Baermann on fresh feces to detect L1
2. Long tapered, sharply pointed posterior end
What is the treatment of Protostrongylus?
1. Levamisole
2. Extra-label: Benzimidazoles and Ivermectin (very effective against P. rufescens)
Describe Muellerius spp.
1. Hair lungworm of small ruminants
2. Adults: tiny, fine white worms
Males: 12-14 mm with tiny bursa + spiral tail
Females: 19-23 mm
3. Occur deeply embedded in lung tissue
Adults, eggs and L1 occur in lungs
Only see clinical signs in heavy infection
4. Indirect life cycle: land snails serve as intermediate host
What is the life cycle of Muellerius spp?
1. Adults in alveoli, sub-pleural granulomas: L1 hatch from eggs in lungs --> L1s coughed up, swallowed, passed in feces

2. L1 enter snails and develop to L3: snail with L3 ingested by new host and L3 migrates to blood, heart and lungs

Prepatent period: 4-6 weeks
Patent period: 5-6 years
What are the clinical signs of Muellerius spp?
1. Usually asymptomatic
2. Heavily infected host can develop: bronchopneumonia, cough, fibrinous pleuritis
3. Pneumonia often due to secondary infections: M. capillaris in goats can cause severe clinical interstitial pneumonia
What are the lesions of Muellerius spp?
1. Sub-pleural granulomatous nodules
2. < 2 cm, grey-green grossly visible on lung surface
3. Young nodules contain adults, eggs and L1
4. Older nodules often calcified and contain no parasites
5. Can diagnose @ necropsy + parasite
What is the treatment of Muellerius?
1. Extra-label
2. Efficacious anthelmintics: Benzimidazoles, Levamisole, and Ivermectin
Describe Dictyocaulus filaria.
1. Protruding protoplasmic knob on head
2. Many dark food granules in intestinal tract
3. Tail ends in blunt point
What are the swine lung worms?
Superfamily Metastrongyloidea:
1. Metastrongylus apri
2. Metastrongylus pudendotectus
What is the Metastronglus structure?
1. Adults: white, ~2 inches long with 6 lips around the mouth; male has reduced (small) bursa

2. Eggs: colorless with thick rough shell; contain L1 when passed in fresh feces
What is the life cycle of Metastrongylus spp?
Adults in bronchioles lay eggs --> eggs coughed up and swallowed --> egg or L1 ingested by earthworm --> L3 develops in 10-30 days --> earthworm eaten by pig --> L3 penetrate gut wall --> lymphatics --> heart --> lungs --> alveoli --> bronchioles --> mature to adults

Prepatent period ~3-4 weeks
What is the epidemiology of swine lung worms?
1. Eggs resistant to environmental extremes: survive in soil for long period of time

2. L3 can live years in earthworms: can survive for several weeks in dead earthworms
What are the lesions of Metastrongylus?
1. Due to larvae: petechial hemorrhages in lungs

2. Due to adults: obstruction of bronchioles, verminous pneumonia, consolidation and/or emphysema
What are the clinical signs of Metastrongylus?
1. Not as pathogenic as ruminant lung worms: older animals relatively resistant; signs more likely in young growing pigs

2. Can have secondary infections: possible vector for swine influenza, hog cholera, mycoplasma
What is the diagnosis of Metastrongylus?
1. Clinical signs suggestive
2. Flotation on fresh feces: eggs with an L1; unreliable method - false negatives occur; some suggest zinc or magnesium sulfate instead of sugar solution; necropsy - adults in bronchioles
How do you control Metastronglyus spp?
1. Sanitation: prevent earthworms from ingesting eggs/larvae from swine feces

2. Prevent access of hogs to earthworms: raise on cement or in confinement; use nose rings to prevent rooting in soil
What is the treatment of Metastrongylus spp?
Fenbendazole, Ivermectin or Levamisole
Describe Parelaphostrongylus tenuis.
Meningeal worm, brain worm

Natural definitive host = white tail deer

Require terrestrial snails or slugs as IH
What do adults of Parelaphostrongylus tenuis look like?
Long (2-4 inches) and slender

Red-brown to straw-colored when fresh
What do L1 of Parelaphostrongylus tenuis look like?
Have dorsal spine on cuticle of tail
If L3s of Parelaphostrongylus tenuis exit the snail/slug, can it survive?
Can survive cold stress ( 4 degrees to 10 degrees C ) and desiccation

L3 retain motility but infectivity not determined
Parelaphostrongylus tenuis life cycle.
White tail deer (adults) --> L1 in environment --> Snails --> L3 --> ingested by WTD --> penetrate gut wall into peritoneal cavity --> follow spinal nerves to vertebral canal --> follow spinal nerve to dorsal horn grey matter --> develop to L4 --> exits cord into subdural space --> mature adults and mate
How do eggs of Parelaphostrongylus tenuis travel?
Female deposit round eggs into venous blood --> eggs carried in blood to heart and lungs --> eggs lodge in lung capillaries and develop into L1 --> trapped in granulomas --> escape --> coughed up, swallowed, pass through GI tract and exit in feces
Pathogenesis of clinical signs of Parelaphostrongylus tenuis.
WTD = asymptomatic

Accidentdal hosts: clinical signs result from damage to spinal cord during larval migration in parenchyma --> hemorrhagic tracts and inflammation

Most common: ataxia, hypermetria, rear limb weakness - difficulty rising or inability to rise
Treatment of Parelaphostrongylus tenuis.
Kill parasite with anthelmintic = fenbendazone

Minimize inflammatory response to antigens of dead parasite with anti-inflammatory

Maintain/restore function
Structure of Oslerus osleri (tracheal worm of wild canids and dogs)
Adults: very small (5-15 mm), slender; females are ovoviviparous

Eggs and L1: eggs thin-shelled (contain a fully-developed L1 that hatches in the host); L1 tail is short and S-shaped (kinked)
What is the life cycle of Osleurus osleri?
Adults: sub-mucosal nodules in trachea and bronchi NEAR TRACHEAL BIFURCATION --> eggs hatch in host --> L1 present in feces or saliva --> L1 directly infective to new host by ingestion (require no period of development outside host)
What is the transmission route of Oslerus osleri?
Ingestion of L1 from infected animal: from bitch to pup - regurgitative feeding (L1 coughed up and swallowed so present in stomach contents fed to pups)

What are clinical signs of Oslerus osleri?
Verminous nodular bronchitis

Nodules obstruct airways: dyspnea, wheezing, harsh dry cough
What are the lesions of Oslerus osleri?
Sub-mucosal nodules in trachea and bronchi: gray, well-circumscribed, holes for females to protrude and discharge larvae
How do you detect L1 in feces or saliva or tracheal wash?
Zinc sulfate centrifugal flotation
Prevention and control for Oslerus osleri?
Very difficult to prevent transmission from bitch to offspring: deliver pups by C-section and hand-feed in isolation from other dogs

Prevent pet dogs from ingesting regurgitated food or feces from wild canids
Describe Filaroides hirthi and milksi
Adults occur in bronchioles and alveoli: eggs and L1 elicit granulomatous penumoa; infection usually asymptomatic

F. hirthi: do NOT have a kinked tail
F. milksi: have a kinked tail
Describe Crenosoma vulpis
Fox lung worm

Adults: upper airways of wild canids, dogs, and racoons; small ~16 mm; INDIRECT life cycle (gastropod intermediate); prepatent period = 19 days
What are the clinical signs of Crenosoma vulpis?
1. Upper resp: nasal discharge, rhino-tracheitis, bronchitis

2. Heavy infection: severe broncho-pneumonia

3. Persistent productive cough non-responsive to antibiotics - can elicit cough by tracheal palpation
What is Aelurostrongylus abstrusus?
Cause of feline verminous pneumonia; mainly in SE coastal states and west
Life cycle of Aelurostrongyles.
Adults in lung parenchyma: in "nests" or sub-pleural gray-white nodules; eggs hatch in the host; L1s coughed up, swallowed and pass in feces --> penetrates snail/slug intermediate host --> L3 develops --> ingested by host (prepatent period = 5-6 weeks)