Trichostrongyles #3

Question 1

What are the species for lungworms for Cattle?

• Indirect/Direct life cycle?
• Where do you find L1?
• What’s the infective larvae?
• Where do the adults live?

Answer 1

• Dictycolus viviparous
  
  • Direct life cycle
  • see L1s in feces
  • L3 is infective
  • Adult dictycolus live in bronchii

Question 2

What are the species for lungworms for equine?

• Indirect/Direct life cycle?
• Where do you find L1?
• What’s the infective larvae?
• Where do the adults live?

Answer 2

• Dictycocaulus arnfieldi
  
  • Direct life cycle
  • See L1 in feces
  • L3 is infective
  • find adults in bronchii

Question 3

What are the species for lungworms for small ruminants?

Answer 3

• Dictyocaulus filaria
• Protostrongylus
• Muelleris

Question 4

What are the species for lungworms for carnivores?

Answer 4

• Filaroides osleri
• Crenosoma vulpis
• Troglostrongylus
• Aluerostrongylus abstruss

Question 5

Dictyocaulus filaria

• Indirect/Direct life cycle?
• Where do you find L1?
• What’s the infective larvae?
• Where do the adults live?

Answer 5

• Direct
• L1 in feces
• L2 has cephalic button
• L3 is infective
• Live in bronchii

Question 6

Protostrongylus

• Indirect/Direct life cycle?
• Where do you find L1?
• What’s the infective larvae?
• Where do the adults live?

Answer 6

• Indirect
  
  • gastropod
• L1 have long tapered tail
  
  • infect gastropod as L1
• L3 are infective from IH to new host
• Live in bronchi

Question 7

Muelleris

• Indirect/Direct life cycle?
• Where do you find L1?
• Where do the adults live?

Answer 7

• Indirect life cycle
  
  • IH: snail
• L1 have a dorsal spine
  
  • find embedded in alveoli, subpleural granulomas
• adults live in parenchymal tissue
  
  • create grayish granulomas
  • find embedded in alveoli, subplerual granulomas

Question 8

Filaroides osleri

• Indirect/Direct life cycle?
• What’s the infective larvae?
• Where do the adults live?

Answer 8

• Direct life cycle
• L1 are infective
  
  • L1 have a kink in the tail
• Live in carina

Question 9

Crenosoma vulpis

• Indirect/Direct life cycle?
• Describe the L1

Answer 9

• Indirect
  
  • gastropod IH
• L1 has no kink in tail

Question 10

Troglostrongylus

• Indirect/Direct life cycle?
• Where do the adults live?

Answer 10

• Indirect
• live in bronchii

Question 11

Aelurostrongylus abstruss

• Indirect/Direct life cycle?
• Describe L1.
• Where do the adults live?

Answer 11

• Indirect life cycle
  
  • gastropod IH
• L1 has kink in tail and a spine
• live in parenchymal tissue

Question 12

• The “fox bronchial worm” referes to which parasite?
• Describe the life cycle
  
  • include prepatent period as well

Answer 12

• Crenosoma vulpis
• Indirect life cycle
  
  • Ovoviviparous female in bronchi
  • Larvae in feces
  • gastropod IH +/- paratenic hosts
  • L3 is infective
• Pre-patent period: 19 days

Question 13

• If a patient comes into your office, what would you ask the owner about the patient’s lifestyle that would lead you to diagnosing Crenosoma vulpis?
• How would you detect Crenosoma vulpis?
  
  • what are you looking for?

Answer 13

• Does your pet have a history of going outdoors?
• Use Baermann method or tracheal wash
  
  • looking for L1 in feces or sputum

Question 14

True/False: Troglostrongylus and Crenosoma both infect canines.

True/False: Treatment for Crenosoma is extra-label use.

Answer 14

• False
  
  • Troglostrongylus is essentially the same as Crenosoma but infects felines.
• True
  
  • suggested: fenbendazole, milbemycin oxime, prednisone

Question 15

• Aelurostrongylus abstrusus causes which disease?
• Describe the life cycle

Answer 15

• cause of feline verminous pneumonia
  
  • occurs in raccoons too
  • found in SE coastal states
• Indirect
  
  • ovoviviparous
    
    • eggs hatch in host
  • in “nests” or sub-pleural gray-white nodules
  • L1 are coughed up, swallowed and passed in feces
  • L1 penetrates gastropod (IH)
  • Infective L3 develops in gastropod
  • New host is infected by ingesting L3 in gastropod or what had eaten the infected IH

Question 16

• How do you diagnose Aelurostrongylus?
• What do you look for?

Answer 16

• Use Baermann method
• Look for L1 in fresh feces
  
  • Have kinked or S-shaped tail with dorsal cuticular spine

Question 17

• What do you treat Aelurostrongylus with?
• What parasite is known as “The French Heartworm”?

Answer 17

• fenbendazole or ivermectin
  
  • extra-label
• Angiostrongylus vasorum
  
  • been reported in Canada

Question 18

Which species can be affected by Angiostrongylus vasorum?

Answer 18

• it’s the blood worm of rats
  
  • in US
  • can cause encephalitis in humans

Question 19

• Which parasite finds it’s natural definitive host in white-tailed deer?
  
  • what are some common accidental hosts?
  • What does this parasite require as a intermediate host?

Answer 19

• Parelaphostrongylus tenuis (meningeal/brain worm)
  
  • Requires terrestrial snails or slugs
  • Camelids, sheep, goats, other cervids, rarely in cattle and horses
    
    • animal is at risk wherever habitat shared with WTD

Question 20

• Describe the adult Parelaphostrongylus tenuis.
• What morphologic feature(s) does a L1 Parelaphostrongylus have?
  
  • what other species have same feature(s)?

Answer 20

• adults
  
  • long (2-4 in) and slender
  • red-brown to straw-colored when fresh
• L1
  
  • dorsal spine on cuticle of tail
  • also present on L1 of Muellerius and other species of Parelaphostrongylus

Question 21

• What’s the meningeal worm lifecyle in WTD?

Answer 21

• Ingested L3 released from IH tissue into gut
• Penetrate gut wall into peritoneal cavity
• Follow spinal nerves to vertebral canal
  
  • Takes 6-10 days in WTD
• L3 follow spinal nerve to dorsal horn grey matter
  
  • # 10 –> #8
• Remain quiesccent in dorsal horn grey matter for ~30 days
  
  • develop into L4
• L4 exits cord into subdural space
  
  • # 7 at ~40 days post infection
• Migrate in subdural space to cranium
  
  • mature into adults andmate
  • remain in cranium for up to 6 years

Question 22

How do white-tailed deer become infected with Parelaphostrongylus tenuis?

Answer 22

• WTD infected during 1st year of life
• ingesting IH containing infective L3 whie grazing

Question 23

• What happens to eggs after Parelaphostrongylus mature and mate?

Answer 23

• Females deposit round eggs into venous blood
  
  • carried in blood to heart and lungs
• lodge in lung capillaries
  
  • develop into L1
• Host cells trap MW eggs and L1 in granulomas
• L1s escape granuloma and enter airways
• L1s coughed up, swallowed, and pass through GI tract and exit in feces
  
  • L1 in mucus coating on WTD fecal pellets

Question 24

True/False:

• Parelaphostrongylus tenuis L1 die off when winter comes and brings with it freezing coniditions.
• L1s develop to infective L3 in gastropods.
• When diagnosing an alpaca for meningeal worm, look for L1s in the feces to run a Baermann method.
• There’s no definitive ante-mortem diagnostic method available for any host for Parelaphostrongylus tenuis.

Answer 24

• False
  
  • L1 can survive freezing conditions and can infect IH next spring
• True
• False
  
  • You wont’ see larvae/eggs in feces because they don’t leave CNS when they get to cranium in an accidental host
• True
  
  • Baermann method detects L1 in feces
    
    • not specific for P. tenuis
  • Find adults in/on meninges of brain at necropsy

Question 25

What does a terrestrial gastropod need from an environment to survive? Where can you find them?

Answer 25

* need environment with high humidity * occur on uderside of wood and pasture debris

Question 26

Describe the MW life cycle in accidental hosts. Does Parelaphostrongylus tenuis complete it's life cycle in an accidental host?

Answer 26

* MW larvae follow same migration pathway and time frame as in WTD * No, accidental hosts are often incapacitated before parasite can complete its life cycle

Question 27

* Descibe the pathogenesis of clinical signs for: * WTD * Accidental host

Answer 27

* asymptomatic * signs: * damage to spinal cord during larval migration in parenchyma * leads to hemorrhagic tracts and inflammation * could also be asymptomatic

Question 28

What are some clinical signs in accidental hosts of Parelaphostrongylus tenuis?

Answer 28

* signs: * ataxia, hypermetria, rear limb weakness, difficulty/inability to rise * camelids: * signs often first noticed as unsteadiness at dung pile * also: tail deviation, head tilt, or cranial nerve deficits

Question 29

* When you think P. tenuis might be the parasite causing neurologic problems in the alpaca, what pertinent question(s) about living conditions? * What would you find if you tested the CSF?

Answer 29

* Are the alpacas grazing in endemic area where WTD present within 3-4 months onset of signs? * Should see eosinophilic pleocytosis * increased eosinophils in CSF

Question 30

* Can anthelmintics kill this parasite? * What treatment do you reccomend for this disease post 40 days since infection?

Answer 30

* Once in CNS it's tough for anthelmintics to reach P. tenuis * Minimize inflammtory response to parasite antigens * NSAIDS * recovery is often prolonged * downers may not recover adequately

Question 31

* How would you prevent MW infection? * Are there any problems with any of these methods?

Answer 31

* prevent by: * Prevent esposure to infective L3 in IH * clear pasture of snal/slug habitat * exlude WTD from pastures * Prophylactic anthelmintics during periods of exposure to IH * prophylactic anthelmintic use selects for resistant GI nematodes to anthelmintics

Question 32

Describe the morphology of adult hookworm.

Answer 32

* hooked anterior end * highly cuticularized buccal capsule * equipped with teth * teeth are at entrance of buccal cavity * bursate males

Question 33

* How do hookworms get their nutrition?

Answer 33

* Attach to host intestinal mucosa and suck blood * infect a wide range of mammals

Question 34

Describe the basic hookworm life cycle.

Answer 34

* direct life cycle * adults in host small intestine * Egg to infective L3 in environment * in fresh feces, egg contains morula * Morula to L1 inside egg * L1 hatches then matures to L2 then L3 * free living from L1-L3 * L3 infective to new host

Question 35

What are the routes of infection by L3? Once in host tissue what does L3 do?

Answer 35

* routes: * percutaneous * skin penetration * ingested from environment or in tissues of paratenic host * L3 migrate in host tissues to intestine * larval arrest or hypobiosis can occur

Question 36

* What hookworms of dogs and cats should be aware of?

Answer 36

hookworms * Ancylostoma caninum * common dog hookworm * Uncinaria stenocephala * mainly dogs * A. tubaeforme * common hookworm in cats * A. braziliense * both dogs and cats * tropics and subtropics

Question 37

Describe Ancylostoma caninum morphology in adults.

Answer 37

* fresh worms are red/gray * 1/2 inch long * Anterior end bent dorsally * "hooked" * large buccal cavity with mouth * 3 pairs of teeth * males have large copulatory bursa

Question 38

What do canine hookworm eggs look like?

Answer 38

strongyle-type egg

Question 39

True/False: * Ancylostoma caninum is very common in dogs of all ages in midwest US. * A. caninum survives during winter months in Iowa and even better in summer months in AZ.

Answer 39

* True * False * L3 survive best in moist, sandy loam soils at moderate temperatures * DO NOT survive well below freezing or above 99 degrees Fahrenheit

Question 40

Describe the life cycle of A. caninum.

Answer 40

* Adults in small intestine * females oviparous * eggs with morula in feces * environment: * within egg: morula -\> L1 -\> hatches from egg * L1 develops and molts -\> L2 forms -\> sheathed L3 in environment * Pre-patent period: ~16 days * L3 ingested or penetrates skin of new host * can penetrate unbroken skin

Question 42

What's the fate of A. caninum if host acquired by skin penetration?

Answer 42

* undergo blood-lung migration * larvae enter venous blood/lympatics in skin * go to heart -\> lungs -\> alveolar capillaries * Decision time for L3 * tracheal migration or somatic migration