Lungworms

Question 1

What are the 3 primary lungworms of ruminants?

Answer 1

Dictyocaulus

• Protostrongylus*
• Muellerius*

Question 2

Dictyocaulus spp. is typically found in what climate?

Answer 2

Moist, temperate climates.

Tends to be found around the tropics.

Question 3

Name the primary hosts for these species:

• Dictyocaulus viviparous*
• Dictyocaulus filaria*
• Dictyocaulus arnfieldi*

Answer 3

• D. viviparous
  
  • ​cattle, bison, camelids, wild ruminants
• D. filaria
  
  • ​sheep, goats, wild ruminants
• D. arnfieldi
  
  • donkey, horse

Question 4

Is Dictyocaulus viviparous in fact viviparous?

(The answer…may surprise you)

Answer 4

Lol Nope.

D. viviparous is, in fact, ovoviviparous.

Recall that this means eggs are laid containing and L1 larva.

Question 5

How would you describe these lips (other than sensuous)?

Answer 5

Pair of tri-lobe lips.

This is characteristic of Dictyocaulus adults.

Question 6

What characteristic can you use to know that you are looking at a Dictyocaulus spp. larva?

Answer 6

Brown food granules in intestine.

Question 7

Where do adult Dictyocaulus live?

Answer 7

Bronchi and bronchioles

Lay eggs, which are coughed up, swallowed, and passed in the feces.

Question 8

Describe the larval migration of L3 Dictyocaulus once swallowed.

Answer 8

Gut, lymphatics, thoracic duct, blood, heart, lung, pulmonary capillaries, alveoli, bronchioles and bronchi.

Question 9

So, like, if Dictyocaulus adults live in the lungs, how do the eggs get into the feces?

Answer 9

Eggs are coughed up, swallowed, and passed in the feces.

Question 10

List the prepatent periods of each of the Dictyocaulus species.

Answer 10

• D. viviparous
  
  • 4-10 weeks
• D. filariae
  
  • 4-6 weeks in goats, 8 weeks in sheep
• D. arnfieldi
  
  • ​4-5 weeks

Question 11

What do larval Dictyocaulus feed on?

Answer 11

Trick question!

The larvae do not feed, but rely on stored food granules in the gut.

Question 12

In what scientists are calling “rad” and “totally awesome,” Dictyocaulus larvae rely on this fungal species for dispersion.

Answer 12

Pilobolus

Question 13

True or False:

The penetration phase with Dictyocaulus tends to be asymptomatic.

Answer 13

True

This phase involves L3 migration from the gut to the lungs via the lymphatics, then the blood stream.

Question 14

What kind of exudate would you expect to find in the bronchioles of an animal infected with Dictyocaulus during the prepatent phase?

Answer 14

Eosinophilic exudate

Question 15

What kind of pathology would you expect to see during the patent phase of a Dictyocaulus infection?

Answer 15

• Adults in the upper airway result in severe bronchitis and epithelial damage.
• Airways blocked by worms.
• Frothy mucus + cellular exudate.
• Emphysema and consolidation of lobules.
• Secondary infection, pneumonia.

Question 16

These worms were found in the lung of a cow. What species do you suspect?

Answer 16

Dictyocaulus spp.

Whenever you see a mass of worms in the bronchi of a ruminant, you should think Dictyocaulus.

Because this is a cow, the species is probably Dictyocaulus viviparous

Question 17

Wow look, cytology! And things are happening on it!

Answer 17

Dictyocaulus worms in bronchi. Note the inflammatory exudation and cellular infiltration.

Question 18

These are lungs. But not normal lungs! What’s going on?

Answer 18

Interstitial emphysema.

In this case, this is parasitic bronchitis caused by infection with adult Dictyocaulus worms.

Question 19

What happens in the post-patent phase of Dictyocaulus infections?

Answer 19

Worms are usually expelled due to the massive immune response.

Worms may not be completely expelled in the case of very large infections.

Some animals may have impaired pulmonary function even after expelling the worms.

Question 20

When are Dictyocaulus infections most common?

Answer 20

Usually occur in the fall (Sept - Oct)

L3 larvae tend to prefer cool, wet weather

Question 21

What factors affect the severity of Dictyocaulus infections?

Answer 21

Number of parasites

Size and location of parasites

Host response to parasites

Question 22

What age of animals tend to be most affected by Dictyocaulus infections?

Answer 22

Calves and yearlings

(especially when exposed to a new pasture)

Question 23

How can you diagnose Dictyocaulus infections?

Answer 23

Clinical signs (however, these are non-specific)

L1 in fresh feces (Baerman method)

Adult worms detected in necropsy

Question 24

Why is it important to have a fresh fecal sample when trying to detect Dictyocaulus larvae?

Answer 24

You are most likely to find L1 Dictyocaulus larvae in the feces. However, if the animal happens to have a strongyle infection and you let the fecal sample sit for too long, the strongyle eggs may hatch and release their larvae. You may then mistake these larvae for Dictyocaulus.

GET FRESH POO!

Question 25

What is the name of this test, and what is it used for?

Answer 25

Baerman test. Used to collect motile larvae from a FRESH fecal sample. Editor's note: this test REALLY looks like a poop martini.

Question 26

What species is this?

Answer 26

L1 larva of *Dictyocaulus viviparous*. Note the food granules and rounded head.

Question 27

What species is this?

Answer 27

L1 larva of *Dictyocaulus filaria*. Note the cephalic button and blunt tail.

Question 28

Describe the vaccine for *Dictyocaulus* in ruminants.

Answer 28

Uses irradiated larvae, administered orally. This vaccine is not available in the US. INTERESTING STUFF: This was the first vaccine developed against a parasite.

Question 29

What is the definitive host of *Dictyocaulus arnfieldi*?

Answer 29

Donkeys Tends to be most pathogenic in horses

Question 30

Describe the life cycle of *Dictyocaulus arnfieldi*

Answer 30

Adults mate and lay eggs in the bronchi. Eggs coughed up and swallowed. Hatch to L1 in the GI tract or a few hours after defecation. L1 molts to L3 within a week. L3 ingested by host, migrates to bronchi via lymphatics. Pre-patent period: 4-5 weeks.

Question 31

How would you diagnose a *Dictyocaulus* infection?

Answer 31

Clinical signs. L1 in bronchial washings. L1 in feces (make sure to get FRESH feces) Note: *Dictyocaulus arnfieldi* infections are often not patent in horses and ponies.

Question 32

You find this egg in FRESH feces from a horse. What species do you suspect?

Answer 32

This is *Dictyocaulus arnfieldi*. It's difficult to distinguish the species from the egg alone (except in *D. filaria*). You might guess that this was a *Dictyocaulus* based on the host, symptoms, and the fact that this is a larvated egg.

Question 33

You find this specimen in the fresh feces of a horse. What characteristics can you use to help identify it?

Answer 33

Host species, sheathed L2, food granules in gut. This is *Dictyocaulus arnfieldi*

Question 34

How could you prevent and control *D. arnfieldi* infections?

Answer 34

Keep donkeys and horses separated. Quarantine new animals and treat as needed. The BIG 3 anthelmintics are effective as treatment.

Question 35

What kind of life cycle does *Protostrongylus* sp. have?

Answer 35

Indirect Oviviviparous. Eggs hatch in lungs -\> L1 in fresh feces -\> L1 infects snail intermediate host -\> IH ingested by definitive host -\> L3 migrates through lymph nodes then to heart and lungs.

Question 36

List the intermediate and definitive host of *Protostrongylus*

Answer 36

IH: snail DH: small ruminants (sheep and goats)

Question 37

What is the prepatent period of *Protostrongylus*?

Answer 37

1 month

Question 38

There is an additional mode of infection for *Protostrongylus* other than ingestion. What is it?

Answer 38

Transplacental transmission. Larvae migrate to the fetal liver. After birth, they migrate to the lung.

Question 39

*Protostrongylus* is a major problem in this wildlife species.

Answer 39

Bighorn sheep.

Question 40

What are the clinical signs associated with *Protostrongylus* infection?

Answer 40

Local inflammation and exudate in the bronchioles. Epithelial desquamation in alveoli and bronchioles. Lobular pneumonia. Infections are usually subclinical

Question 41

Identify this L1

Answer 41

*Protostrongylus* Note the sharp, tapered tail.

Question 42

Name the intermediate and definitive hosts of *Muellerius* sp.

Answer 42

IH: terrestrial snails DH: small ruminants

Question 43

What are the prepatent and patent periods of *Muellerius*?

Answer 43

Prepatent: 4-6 weeks Patent: 5-6 years

Question 44

What are the clinical signs of heavy *Muellerius* infections?

Answer 44

Bronchopneumonia Cough Fibrinous pleuritis

Question 45

How would you diagnose a *Muellerius* infection?

Answer 45

Baerman on fresh feces to identify L1

Question 46

Identify this L1 (arrow is pointing to a diagnostic characteristic)

Answer 46

*Muellerius* Note the dorsal spine on the tail

Question 47

Tissue from a lung infected with *Muellerius*. Describe the lesions.

Answer 47

Sub-pleural granulomatous nodules Young nodules contain adults, eggs, and L1 Older nodules calcified

Question 48

Identify these larvae and name the features you used to identify them.

Answer 48

Left: *Dictyocaulus filaria* * Cephalic button on head, food granules in gut, tail ends in sharp point Middle: *Protostrongylus* * Long tail tapers to a point Right: *Muellerius* * Tail has an undulating tip and a dorsal spine.

Question 49

What drugs would you use to treat *Protostrongylus* and *Muellerius* infections?

Answer 49

Avermectins Benzimidazoles Levamisole

Question 50

What is the definitive host of *Metastrongylus*?

Answer 50

Pigs

Question 51

What is the distinct morphological feature of adult *Metastrongylus* males?

Answer 51

Reduced copulatory bursa

Question 52

What is the intermediate host of *Metastrongylus*?

Answer 52

Earthworms

Question 53

How does a pig become infected with *Metastrongylus*?

Answer 53

Ingestion of earthworm containing an L3 larva. L3 then migrates through the lymphatics to the blood and then the lungs. Prepatent period: 3-4 weeks.

Question 54

What stage of *Metastrongylus* is shed into the environment?

Answer 54

L1 in eggs

Question 55

*Metastrongylus* can live for years inside its earthworm intermediate host. Which other lungworm can do this?

Answer 55

*Syngamus*

Question 56

What symptoms are associated with infection with *Metastrongylus* larvae and adults?

Answer 56

Larvae: petechial hemorrhages in lungs Adults: bronchiolar obstruction, secondary pneumonia

Question 57

Why is fecal flotation not a reliable method for detection of *Metastrongylus*? What method should you use instead?

Answer 57

Eggs do not float well, which can result in false negatives. Some suggest floating with zinc or magnesium sulfate instead of sugar. Clinical signs are suggestive. Adults can be detected at necropsy.

Question 58

Identify this egg found in the fresh feces of a pig.

Answer 58

*Metastrongylus* Note the thick shell and larvated egg. Do not confuse with *Ascaris*, which is not larvated at this point in time.

Question 59

You find these in the bronchioles of a pig at slaughter check. What species is this?

Answer 59

*Metastrongylus*

Question 60

How would you prevent *Metastrongylus* infections?

Answer 60

Prevent access of hogs to earthworms by: raising on concrete or in confinement use nose rings to prevent rooting in soil

Question 61

What can you use to treat *Metastrongylus* infections?

Answer 61

Fenbendazole Ivermectin Levamisole

Question 62

What is the definitive host of *Crenosoma vulpis*?

Answer 62

Canines and raccoons

Question 63

What is the intermediate host of *Crenosoma*?

Answer 63

Gastropods

Question 64

What is the prepatent period for *Crenosoma vulpis*?

Answer 64

19 days

Question 65

Which stage of *Crenosoma* is infective?

Answer 65

L3 in intermediate host

Question 66

Identify this species

Answer 66

*Crenosoma vulpis* Note the crenations in the cuticle (hence the species name)

Question 67

How would you identify a *Crenosoma* infection?

Answer 67

History of outdoor exposure Clinical signs Detection of L1 in feces or sputum (don't confuse with *Filaroides*) Broncho-interstitial pattern on radiograph

Question 68

How would you distinguish *Crenosoma* L1's from *Filaroides*?

Answer 68

*Crenosoma* does not have a kink in the tail

Question 69

What drugs would you use to treat *Crenosoma vulpis*?

Answer 69

Fenbendazole Milbemycin oxime Prednisone (for inflammation) Note: these are extra-label usage