Lungworms

Question 1

Lungworm classification

Answer 1

Phylum: Nematoda
Order: Strongylida
Superfamily: Trichostrongyloidea
- Dictyocalus viviparous (cattle and deer)
- Dictyocalus filaria (sheep, goats)
Superfamily: Metastrongyloidea
- Muellerius capillaris (sheep, goats)
- Aelurostrongylus abstrusus (felids)
- Filaroides osleri (canids)

Question 2

Dictyocaulus viviparus - hosts

Answer 2

DH: cattle, deer, elk, bison

- sites: trachea, bronchi, bronchioles

Question 3

Dictyocaulus viviparus - life cycle

Answer 3

External environment (4-6 days) 
- L1 in feces --> L2 --> L3 ingested alone or on Pilobolus fungus --> L3 penetrates SI, mesenteric LN --> L4 thoracic duct and right heart, lung, alveoli --> +/- ALD --> adults in lumen of bronchial tree --> eggs embryonate (coughed up. swallowed) --> L1 usually hatch in airway or GIT

Question 4

Pilobolus

Answer 4

Commonly grows on herbivore manure

• larval lungworm nematodes excreted by host, climb up Philobolus sporangiophores –> discharged with sporangium
• exploding fungi spores cast larvae for long distances from cow paddy
• nematodes complete life cycle when they are ingested by new host

Question 5

Dictyocaulus viviparus - pathology

Answer 5

• inflammation of bronchi, plug of eosinophils obstructing small bronhiole
• collapsed alveoli
• epithelialized alveoli
• fibrotic lobes

Question 6

Dictyocaulus viviparus - adult pathology

Answer 6

Moderate to heavy infection

• impaired respiratory function
• death
• infections in deer appear to be associated with cross-contamination with infected domestic species (problem in cattle near deer)

Question 7

Dictyocaulus viviparus - clinical signs

Answer 7

• respiratory: chronic bronchitis, tachypnea, severe dyspnea, extended head, harsh cough
• anorexia
• emaciation
• death

Question 8

Dictyocaulus viviparus - diagnosis

Answer 8

L1 in feces!!

• only L1 of parasitic nematodes found in fresh cattle manure
• prominent granules, bluntly pointed tail, rounded head, granules
• males are bursate
• use Baermann with fresh feces!!

Question 9

Dictyocaulus viviparus - treatment and control

Answer 9

• labeled for cattle: fenbendazole, albendazole, oxfendazole
• vaccine in Europe
• -> disadvantages: short shelf life, radiation attenuated, has to be produced annually, uses donor calves, calves must be boosted from natural challenge to maintain protective immunity

Question 10

Dictyocaulus filaria - hosts

Answer 10

DH: sheep, goats

• sites: bronchi and trachea
• distribution: worldwide, US (NE, central)

Question 11

Dictyocaulus filaria - life cycle

Answer 11

External environment (6-7 days) –> L1 in feces –> L2 –> L3 ensheathed infective stage –> L3 ingested –> L3 penetrates SI, mesenteric LN –> L4 thoracic duct and right heart, lung, alveoli –> +/- ALD, can arrest in L4 or early adults –> adults in lumen of bronchial tree –> eggs embryonate (cough/swallow) –> L1 usually hatch in airway or GIT

Question 12

Dictyocaulus filaria - pathology

Answer 12

• inflammation
• catarrhal bronchitis
• atelectasis
• pneumonia

Question 13

Dictyocaulus filaria - clinical signs

Answer 13

Usually mild, unless large infections

• respiratory: cough, nasal discharge, tachypnea, dyspnea
• weight loss
• febrile with secondary infections

Question 14

Dictyocaulus filaria - diagnosis

Answer 14

L1 in fresh feces 
- bluntly pointed end
- brownish intestinal granules
- button at mouth
- Baermann
- adults on necropsy
Eggs from sputum/nasal discharge (fully larvated)

Question 15

Dictyocaulus filaria - treatment and control

Answer 15

Labeled for sheep: Albendazole, levamisole, ivermectin, fenbendazole (goats)
- management: avoid moist or contaminated pastures

Question 16

Muellerius capillaris - host

Answer 16

DH: sheep, goats
IH: gastropods (snail, slug)
- site: lungs (parenchyma, bronchioles)
- distribution: worldwide, US

Question 17

Muellerius capillaris - life cycle

Answer 17

L1 in feces –> L1 penetrates IH or is swallowed –> L2 –> L3 (infective) –> DH ingests IH –> L3 penetrates gut –> mesenteric LN, heart and lungs –> L4 lung parenchyma –> forms nodules –> adults in nodules in lung parenchyma –> eggs in lung parenchyma –> L1 hatch in lungs –> coughed up and swallowed

Question 18

Muellerius capillaris pathology

Answer 18

Not usually pathogenic

• inflammation
• small nodular lesions

Question 19

Muellerius capillaris - diagnosis

Answer 19

L1 in feces

• Baermann technique of choice
• wavy, pointed tail with dorsal spine!!

Question 20

Muellerius capillaris - treatment and control

Answer 20

Generally not treated

- could use off label dewormers

Question 21

Aelurstongylus abstrusus - hosts

Answer 21

DH: cats
IH: snails, slugs
PH: rodents, birds, amphibians, reptiles
- site: lung parenchyma, terminal respiratory bronchioles, alveolar ducts in nodules

Question 22

Aelurostrongylus abstrusus - pathology

Answer 22

• subpleural nodules
• smooth muscle hypertrophy
• milky lung exudate with eggs and larvae

Question 23

Aelurostrongylus abstrusus - clinical signs

Answer 23

Respiratory

• severe pulmonary disease
• coughing
• tachypnea
• dyspnea
• sneezing
• nasal discharge

Question 24

Aelurostrongylus abstrusus - diagnosis

Answer 24

L1 in fresh feces
- tail curved, dorsal spine
- Baermann
Adults are thread like

Question 25

Aelurostrongylus abstrusus - treatment and control

Answer 25

Off label: fenbendazole, ivermectin | - management: prevent ingestion of intermediate or paratenic host

Question 26

Filaroides osleri - hosts

Answer 26

DH: canids, including wild canids - site: in nodules and trachea and bronchi! - rarely in lungs!!!

Question 27

Filaroides osleri - life cycle

Answer 27

L1 and eggs in feces and saliva --> prepatent period of 10 weeks --> DH ingests L1 or L1 in egg --> lymphatic and venous portal systems --> L1-L4 --> migrates to heart and lungs, bronchi, tracheal bifurcation --> adults in nodules in trachea and bronchi - eggs: larvated, shed in respiratory tract

Question 28

Filaroides osleri - clinical signs

Answer 28

- chronic dry cough - severe respiratory distress - emaciation

Question 29

Filaroides osleri - pathology

Answer 29

Nodules in bifurcation of trachea

Question 30

Filaroides osleri - diagnosis

Answer 30

L1: wavy tail kinked, no dorsal spine - ZnSO4 flotation, NOT Baermann! Direct smears: confirm by bronchoscopy, lesions observed by bronchoscope are pathognomonic

Question 31

Filaroides osleri - treatment

Answer 31

Off label: ivermectin, fenbendazole - successful chemotherapy - nodules resolve, clinical signs disappear, disappearance of larvae from feces