5) +nematodes Fall2020 PDF

ROSS UNIVERSITY SCHOOL OF VETERINARY MEDICINE
VMP 5265 Parasitology

5. Nematodes – Strongylida
Trichostrongyloidea
Oesophagostomum spp. review

• Pimply worm
• Large intestine
• Nodules from L4 in small and large
intestine
• Low EPG; clinical signs pre EPG
• Anorexia
• Ruminants: diarrhea
• Swine: decreased production; “poor sow”
syndrome
Syngamus trachea review

• Gapeworm
• Operculated egg in feces
• L3 (in or out of egg); earthworms PH
• Trachea/lungs
• Mucus build-up, suffocation
• Especially important in game birds
Lecture topics
Introduce the Trichostrongyloidea

• Review general characteristics
Discuss 11 parasites
Trichostrongyloid
Trichostrongyle
Strongyloid
strongyle
Learning objectives
Trichostrongyloidea
• General characteristics
• Life cycle, infective stage, diagnosis
Discuss 11 parasites
• Age of animal; seasonality
• Clinical signs
• Diagnosis
Order Superfamily Typical features

Bursate nematodes
Strongylida Ancylostomatoidea • Life cycle direct
Ancylostoma, etc. • Infection by L3
Strongyloidea • Buccal capsule well
Strongylus, developed; leaf crowns
Syngamus, etc. and teeth
• Life cycle direct
• Infection by L3
Trichostrongyloidea • Buccal capsule small
Trichostrongylus, • Life cycle direct
Dictyocaulus, etc • Infection by L3
Metastrongyloidea • Buccal capsule small
Metastrongylus, • Life cycle indirect
Aelurostrongylus, • Infection by L3 in
Filaroides* intermediate host
• *L1; No IM
Nematodes – Thin vs Thick
http://vetpda.ucdavis.edu/parasitolog/#_images
Trichostrongyloidea
• Tricho – hair like; thin body

• A thinner Strongyle!
• Life cycle: direct; infection by L3
• Eggs: thin shelled; oval; average size
• Arrested development
• Males have a bursa
• Some exceptions
Trichostrongyloidea -- Direct life cycle

Trichostrongyloidea
Fig 1.125 Zajac and Comboy 8th ed

Trichostrongyloidea
N. Taira, Y. Ando and J.C. Williams. 2003. A Color Atlast of

Clinical Helminthology of Domestic Animals. Elsevier.
Trichostrongyloidea
Photo: J. Ketzis
Trichostrongyloidea
• Egg differentiation
• Cattle develop immunity with age
– Trichostrongyloidea NOT
Strongyloidea
– Fewer parasites, fewer eggs
• Immunity: Cattle > Sheep > goats
• PPR sheep, goats and swine
Trichostrongyloidea & Strongyloidea
Zajac and Conboy 2012
Copyright: RC Krecek
RUSVM
Superfamily Trichostrongyloidea
The stomach worms
• Ostertagia ostertagi
• Teladorsagia circumcincta
• Hyostrongylus rubidus
Barber pole worms
• Haemonchus contortus and H. placei
Stress / mismanagement worms
• Trichostrongylus spp. & Cooperia spp.
The lungworms (3 species)
Nematodirus spp.
Ostertagia ostertagi
Common name: brown stomach worm
Host: cattle
Identification
• Adults -- 1 cm; abomasal surface
• Eggs -- trichostrongyloid, 85 μm
Site of infection: abomasum
PPP: 21 d
Arrested L4: up to 6 mo
(http://z.about.com/d/homerepair/1/0/o/3/-/-
/climate_temps.jpg)
UC Davis, 2004
Pathogenesis and lesions
• Caused primarily by L3 to immature adult
in the gastric glands
• Thickened gastric mucosa; raised nodules
= “Moroccan leather”
• Increased plasma pepsinogen
O. ostertagi in gastric gland

Photo copyright: Thomas Nolan
Image copyright Dr. Jorge Guerrero, Merial Inc

Abomasum changes
Photo courtesy of RC Krecek

“Moroccan leather” Characteristic lesions

of ostertagiosis
Photo: Noah’s Archive
Characteristic lesions of ostertagiosis

Photo copyright Thomas Nolan
“Bottle jaw”
http://cal.vet.upenn.edu/projects/fieldserv Photo: Noah’s archive

ice/Dairy/DairyPE/cwPE2.htm
Clinical Signs
• Type I disease Summer Ostertagiosis
(grazing)
– In calves during first grazing season
– Can be 2nd or 3rd season in heavily
infected pastures
– Profuse watery diarrhea
– Morbidity high, mortality rare if
treatment is instituted in 3 days
Clinical Signs
• Type II disease Winter Ostertagiosis
– In calves following first grazing season
with arrested L4
– Can be after 2nd or 3rd season in
heavily infected pastures
– Profuse watery diarrhea; intermittent
– More “bottle jaw”
– Clinical disease low, mortality high
Urquhart et al., 1996. Veterinary Parasitology, 2nd edition. Blackwell. pp 14

http://slideplayer.com.br/slide/3250096/
Ostertagiasis video on Canvas; 12.30 minutes

Diagnosis
• Clinical signs
• Season
• Grazing history
• Fecal egg counts
• Type I have epg
• Type II often negative
• Culture and identification of L3
Diagnosis
• Plasma pepsinogen levels elevated
• Necropsy: worms, characteristic mucosa
• % adults to larvae high in Type I and low
in Type II
Treatment and Prevention
• Type I
– Responds well to anthelmintics
– Move cattle to “safe pasture”
• Type II
– Requires anthelmintics effective against
arrested L4, larvae and adults
• Limiting exposure to infection
• Creating “safe pasture”
• Exposure is needed to acquire immunity
Teladorsagia circumcincta
Sheep and goats
• = Ostertagia ostertagi
• Similar lesions, but less severe clinical
signs than with bovine ostertagiosis
• Weight loss
• Diarrhea intermittent
• Profuse watery diarrhea uncommon
• Sheep feces less protection for L3
• PPR

• Source of infection varies with conditions
during the adverse period for larval
survival
• In very dry hot summer longevity of L3
reduced and mat acts as reservoir
• Sheep feces less protection for L3
• PPR
Diagnosis
• As per Ostertagia ostertagi
Treatment and prevention
• MCLs, benzimidazoles, levamisole
• Which work on the farm?
Hyostrongylus spp.
Common name: Stomach worm
Host: Pigs
Identification
• Slender reddish nematodes
• 5-8 mm long (adults)
• Trichostrongyloid eggs
Location
• Stomach
Hyostrongylus spp.
Hyostrongylus rubidus life cycle
Egg to L3: 1-2 wk

PPP: 3 wk
L4: hypobiotic
PPR
High motility of L3
Hyostrongylus spp.
• Damage to the gastric glands leading to
lowered acidity
• Mucosal hyperplasia
• Nodule formation
• Hemorrhage
Hyostrongylus spp.
Gross lesions (nodules), stomach

Hyostrongylus spp.
Clinical signs
• Inappetence
• Loss of condition and anemia
• Usually, no diarrhea
Diagnosis
• Eggs in fecal examination
• Difficult to distinguish from
Oesophagostomum spp.
Hyostrongylus spp.
• Outdoor pigs usually affected
• “poor sow syndrome”: infection with this
nematode and/or nodular worm
• Anthelmintics that are effective against
hypobiotic larvae
• Pasture management; timing of
treatments as per Ostertagia sp.
www.blog.friendseat.com
The stomach worms
Barber pole worms
Nematodirus spp.
Haemonchus contortus
Common name: Barber pole worm
Hosts: Sheep and goats
Identification
• Adults 2-3 cm on abomasal surface;
females = barber pole
• Eggs trichostrongyloid, 85 μm
Life cycle
PPP
PPR
Hypobiosis
Site(s) of infection
• Abomasum
• Consume blood
• Cause hemorrhagic tracts
• Hyperacute haemonchosis
• Acute hemorrhagic anemia
• Chronic haemonchosis
Clinical signs
• Hyperacute cases lambs die of
hemorrhagic gastritis
• Acute: anaemia, “bottle jaw”, lethargy
• Chronic haemonchosis causes
progressive weight loss and weakness
Hemorrhage in abomassum
Photos copyright Thomas Nolan
Bloodsucking nematodes will lead to anemia

Photo RUSVM
Haemonchus contortus -- chronic
Hoste et al. 2016. Interactions between nutrition and infections with Haemonchus
contortus and related gastrointestinal nematodes in small ruminants. Advances in 55
Parasitol
Diagnosis
• Season
• History
• Clinical signs
• Fecal egg counts and identification of L3
• Necropsy
• MCLs, benzimidazoles, levamisole
• Vaccine in AUS
• Anthelmintic resistance!
• Which work on the farm? Do any work?
• Only treat the sheep/goats that require
treatment
Dr. Ehrhards; http://www.wormx.info/midwest

Trichostrongyle fecal egg counts; ACSRPC

Haemonchus placei
Cattle; sometimes sheep & goats
• Tropics; less cold resistance
• More acute and chronic versus
hyperacute
• Under estimated in importance?
• Resistance
The stomach worms
Barber pole worms
Nematodirus spp.
Trichostrongylus spp.
Hosts: cattle, sheep, goats, equine
Identification
• Adults -- <7 mm
Site(s) of infection
• Abomasum / stomach
• Small intestine
Life cycle typical Trichostrongyloid
• PPP 21-28 d; low hypobiosis
• Most species host specific
• Cattle, sheep and goats can share
parasites
• Anthelmintic resistance
• Heavy infections severe diarrhea
• Low infections problematic in
malnourished or stressed animals
Cooperia spp.
Hosts: cattle, sheep and goats
Identification
• Adults -- <9 mm
Site(s) of infection: small intestine
Life cycle typical trichostrongyloid
• PPP: 15-18 d
Cooperia spp.
cal.vet.upenn.edu; Copyright © 1998 University of Pennsylvania

Cooperia spp.
• Normally mild
Clinical signs
• Stressed cattle produce watery diarrhea
With Ostertagia most common nematodes of
weanling age cattle
(mid to late first grazing)
Cooperia spp.
Diagnosis
• Fecal egg counts
• Trichostrongyloid L3
• Necropsy
• Anthelmintics
• Environment and animal husbandry
important
Cooperia punctata
• Most prevalent nematode in cow-calf
operations
• Decreased feed intake
• Decreased weight gain
• MCLs have lower efficacy against C.
punctata compared to other nematodes
• Resistance is an issue also
The stomach worms
Barber pole worms
Nematodirus spp.
Lungworms
Common name: lung worm

Adults: long (>8 cm), thin, in bronchi
Infective stage: L3
Diagnostic stage: L1 Baermann
Clinical signs: coughing
Dictyocaulus viviparous, cattle: MODEL
Dictyocaulus filarial, goats and sheep
Dictyocaulus arnfeldi, equine
Dictyocaulus viviparous
Life cycle
• Adult females pass eggs, hatch to L1
• L1 coughed up and pass in feces
• L1 develop to L3, migrate up herbage (or
dispersed by fungi)
• L3 ingested; migrate from intestine via
blood to lungs; mature
• PPP: 24 - 35 d (Note longer for other
species)
Dictyocaulus viviparus
UC Davis
Dictyocaulus viviparus
Zajac and Conboy, 2012; Fig. 1.143

Pathogenesis
• Days 1-7: Penetration phase
– Larval migration
– Clinical signs not apparent
• Days 8-24: Prepatent phase
– Larvae develop to adults in lungs
– Alveolitis and bronchitis
Pathogenesis
• Days 25-60: Patent phase
• Presence of adult worms in lungs
• Bronchitis and pneumonia
• Days 61-90: Postpatent phase
• If animal survives, recovery starts
• Relapse can occur; entire lungs diseased
Applies primarily to D. viviparus
Dictyocaulus spp.

Dictyocaulus spp.
Pneumonic lesions of parasitic bronchitis

Clinical signs
• Bouts of coughing at rest
• Postpatent parasitic bronchitis
– Dissolution and aspiration of dead or
dying worms at end of infection
Diagnosis
• Clinical signs
• History
• Endemic area
• Identification of L1 (Baermann)
• Necropsy
Baermann Method: L1
Temperature, time, fresh feces

• Anthelmintics
• Management
• Avoid endemic pastures
• Develop immunity with age
• Vaccine (Europe)
• Post treatment syndrome large issue
Dictyocaulus filaria
• Pathology associated with bovine
infection uncommon
• Coughing, unthriftiness
• Less immunity
Dictyocaulus arnfieldi
Donkeys
• Adapted
• Few to no clinical signs
• Animals of all age
• Egg with L1 or L1
Dictyocaulus arnfieldi
Horses
• Rarely reaches sexual maturity; foals and
yearlings exception
• Damage to pulmonary tissue
• Chronic cough
• Bronchial alveolar lavage
• In endemic areas do not pasture horses
and donkeys together
The stomach worms
Barber pole worms
Nematodirus spp.
Nematodirus spp.
Common name: Long neck bankrupt worm
Hosts: Sheep, goats, cattle
Identification
• Adults large 2.5 cm
• Eggs very large 130 μm
Site(s) of infection: Small intestine
Nematodirus spp.
Photo: Thomas Nolan
Photo: Bowman et al., 2003

Zajac and Conboy, 2012; Fig 1.131
Nematodirus spp.
Life cycle
• L1 to L2 to L3 ALL inside the egg
• L1 to L3 at least 2 months
• L3 can survive in egg up to 2 y
• L3 infective
Nematodirus spp.
PPP 3 weeks
http://cal.vet.upenn.edu/projects/merialsp/Trichosp/trich7a2sp.htm
Nematodirus battus
Factors influencing disease
• Require a “freeze” and then warmth for L3
to emerge from egg
• Large numbers emerge at same time
• Normally in spring
• Lamb-to-lamb disease
Other species not seasonal
Nematodirus battus
• Larval stages; development disrupts
intestinal mucosa
• Carcass dehydrated
Clinical signs
• Sudden onset of ill thrift in lambs
• Severe diarrhea
• Mortality can reach 30%
Nematodirus battus
Diagnosis
• Clinical signs during PPP
• Egg counts are of little value
• When eggs, epg low (600-3000)
• Grazing history
• Necropsy
– Dehydrated carcass
– Mild catarrhal (inflammation of a
mucous membrane) enteritis
Nematodirus battus
• Avoid pastures used the previous year in
the spring/early summer
• Prophylactic treatment; predictions
The stomach worms
Barber pole worms
Nematodirus spp.
1.
This egg (approx. 90 x 40 um) was seen in the feces of a 2
year old cow. Which parasites can it represent in this
animal?
a. Strongylus spp., Teladorsagia sp., Ostertagia sp.

b. Strongylus spp., Ostertagia sp., Trichostrongylus sp.
c. Ostertagia sp., Trichostrongylus sp., Cooperia sp.,
Hyostrongylus sp.
d. Ostertagia sp., Trichostrongylus sp., Cooperia sp.
2.
A sow is suffering from poor sow syndrome. She presents
with little diarrhea but has anemia. Which parasite is
highest on your list of differentials?
a. Hyostrongylus sp.
b. Trichostrongylus sp.
c. Cooperia sp.
d. Oesophagostomum sp.
3.
Several young horses (<6 months old) present with
diarrhea. They have been grazing for < 6 weeks. Which
parasite would be high on your list of differentials?
a. Trichostrongylus sp.
b. Strongylus vulgaris
c. Strongylus edantatus
d. Small strongyles
4.
For which parasite is the periparturient rise NOT an
important source of infection for young grazing sheep?
a. Teladorsagia circumcincta
b. Dictyocaulus filaria
c. Trichostrongylus sp.
d. Nematodirus battus
e. Haemonchus contortus
5.
A fecal flotation was performed with feces from beef cattle.
Eggs such as those below were seen. These eggs can
represent which parasites of cattle?
a) Cooperia spp., Trichostrongylus spp., Teladorsagia sp.

b) Cooperia spp., Trichostrongylus spp., Oesophagostomum spp.,
Ostertagia sp., Haemonchus sp.
c) Trichostrongylus spp., Oesophagostomum spp., Dictyocaulus sp.
d) Trichostrongylus spp., Oesophagostomum spp., Ostertagia sp.,
Cooperia spp., Nematodirus sp.
e) Haemonchus sp., Dictyocaulus sp., Ostertagia sp.,
6.
Eggs of the types below were seen in the feces of a 2 year old
sheep with diarrhea on pasture mid-summer. Which parasite(s)
is/are highest on your differentials as the cause of the diarrhea?
a) Nematodirus sp.
b) Nematodirus sp. and Teladorsagia sp.
c) Nematodirus sp., Teladorsagia sp., Cooperia sp.,
Trichostrongylus sp.
d) Teladorsagia sp. and Haemonchus sp.
e) Teladorsagia sp.
Answers
1. D
2. A
3. A
4. D
5. B
6. E – Nematodirus is an issue in lambs, Haemonchus
causes anemia
Recaps
• Which parasites cause poor sow

syndrome?
• This egg can represent which parasites in
a horse? In a pig? In a cow? In a sheep?
Recaps
• In which animals does the periparturient

rise occur? With which parasites? Why
does it occur and what is the point of it?
• Which parasites are more likely to cause
clinical signs in a 2 year old cow? In a 5
year old cow?
• Which parasites cause “bottle jaw” and
how can they be differentiated?
Recaps
• Why does a pasture become more rapidly

infested with L3 from small strongyles
compared to large strongyles?
• Why is mortality higher with type II
ostertagiosis compared to type I?
Recaps
• A fecal egg count was 1000 epg for

trichostrongylid type eggs. The animal
was treated and it is now 200 epg. Instead
of stating that there is potentially
“trichostrongylid” resistance, you state
that there is Ostertagia resistance. How
would you have determined this? Why is
this important?
Recaps
• Culture to L3 to determine % of each type

of trichostrongyle egg. Alternatively,
submit to a specialized laboratory for
PCR.
• For example: of the 1000 eggs, 10% are
Trichostrongylus sp., 10% are Cooperia
sp. and 80% are Ostertagia sp.
• Of the 200 eggs post treatment, 100% are
Ostertagia sp.: (800-200/800) *100 = 75%
fecal egg count reduction.
Trichostrongyles Recaps
General characteristics
• Tricho – hair like; thin body
• Life cycle: direct; infection by L3
• Males have a bursa
• Arrested development, PPR in goats & sheep
• Immunity cattle>sheep>goats
• Diagnosis
– Egg (McMaster) thin shelled; oval; average
– Dictyocaulus L1 (Baermann)
– Nematodirus large egg
Trichostrongyle & Strongyle Recaps
Photo courtesy of Dr. Thomas Nolan
For each parasite

1. Consider location in host
2. Pathology based on larvae or adult behavior & location
3. Insert impact of arrested/hypobiotic stages
Stomach worms
Ostertagia ostertagi, Teladorsagia

circumcincta, Hyostrongylus rubidus
• Adults 1 cm on abomasal surface; Eggs
are trichostrongyloid, 85 μm
• Life cycle: PPP 21 d; arrested L4
• Abomasum / stomach
• Damage from L3 to immature
• Glandular changes; “Moroccan leather”;
increased plasma pepsinogen
Stomach worms
• Ruminants: diarrhea; sheep/goats < cattle

• Swine: decreased production; “poor sow”
syndrome
• Type I: Morbidity high; treat and move
• Type II: clinical disease low, mortality;
anthelmintics with effect against L4;
prevent with treatment winter housing
• #1 parasite of cattle

O. ostertagi emerging from a gastric gland
Emergence causes a cascade of changes =
pathology
Haemonchus spp.
• Adults 2-3 cm on abomasal surface; Eggs
are trichostrongyloid, 85 μm
• PPP 23-28 d; Arrested L4
• Acute haemonchosis: bottle jaw; lethargy
• Chronic haemonchosis: weight loss;
weakness
• Season, history, clinical signs, epg
• Limit exposure; selective treatment;
FAMACHA© for sheep and goats
• #1 killer of sheep and goats; Resistance!
Anemia most common sign; bottle jaw can occur
http://cal.vet.upenn.edu/projects/m
erial/Introduction/images/bottle%2 http://www.luresext.edu/goats/training/parasi
0jaw.jpg tes.html#abom
Trichostrongylus spp. & Cooperia spp.

• Abomasum, stomach, small intestine
Cooperia spp.
• Small intestine
Diarrhea
Heavy infections or malnourished or
stressed animals
Nematodirus spp.
• Large egg
• Lamb to lamb
• Diarrhea; dehydration
• Clinical signs before eggs in feces
• PPR is NOT important for this parasite
Dictyocaulus spp.
• Common name: lung worm
• Adults: long (>8 cm), thin, in bronchi
• Infective stage: L3
• Diagnostic stage: L1 Baermann
• Clinical signs: coughing
• D. viviparous: post-treatment syndrome
• D. arnfieldi: adapted to donkeys and not
horses; rarely patent in horses
Periparturient rise (PPR)
• Peri = around
• Parturition = birthing
• Rise = increase in eggs in feces
• Caused by
• Relaxation of immunity
• Increased adult worms
• Increased egg output

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ROSS UNIVERSITY SCHOOL OF VETERINARY MEDICINE

VMP 5265 Parasitology

Oesophagostomum spp. review

Syngamus trachea review

Introduce the Trichostrongyloidea

Order Superfamily Typical features

Nematodes – Thin vs Thick

• Tricho – hair like; thin body

Trichostrongyloidea -- Direct life cycle

Fig 1.125 Zajac and Comboy 8th ed

N. Taira, Y. Ando and J.C. Williams. 2003. A Color Atlast of

Trichostrongyloidea & Strongyloidea

Zajac and Conboy 2012

O. ostertagi in gastric gland

Image copyright Dr. Jorge Guerrero, Merial Inc

Photo courtesy of RC Krecek

“Moroccan leather” Characteristic lesions

Characteristic lesions of ostertagiosis

http://cal.vet.upenn.edu/projects/fieldserv Photo: Noah’s archive

Urquhart et al., 1996. Veterinary Parasitology, 2nd edition. Blackwell. pp 14

Ostertagiasis video on Canvas; 12.30 minutes

Photo copyright Thomas Nolan

Hyostrongylus rubidus life cycle

Egg to L3: 1-2 wk

Gross lesions (nodules), stomach

Bloodsucking nematodes will lead to anemia

Haemonchus contortus -- chronic

Dr. Ehrhards; http://www.wormx.info/midwest

Trichostrongyle fecal egg counts; ACSRPC

cal.vet.upenn.edu; Copyright © 1998 University of Pennsylvania

Common name: lung worm

Zajac and Conboy, 2012; Fig. 1.143

Photo: Noah’s Archive

Photo copyright Thomas Nolan

Pneumonic lesions of parasitic bronchitis

Temperature, time, fresh feces

Photo: Thomas Nolan

Photo: Bowman et al., 2003

a. Strongylus spp., Teladorsagia sp., Ostertagia sp.

a) Cooperia spp., Trichostrongylus spp., Teladorsagia sp.

• Which parasites cause poor sow

• In which animals does the periparturient

• Why does a pasture become more rapidly

• A fecal egg count was 1000 epg for

• Culture to L3 to determine % of each type

Trichostrongyle & Strongyle Recaps

Photo courtesy of Dr. Thomas Nolan

For each parasite

Ostertagia ostertagi, Teladorsagia

• Ruminants: diarrhea; sheep/goats < cattle

Photo: Noah’s Archive

Anemia most common sign; bottle jaw can occur

Trichostrongylus spp. & Cooperia spp.

Periparturient rise (PPR)

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