Endoparasites –
Ruminants
Dr. Dipa Brahmbhatt MPH VMD
Goals and Objectives
• Understand the influence of parasitism on
production
• Become familiar with the types of parasites
afflicting agricultural animals
• Understand the public health implications of
selected parasites
• Understand the basic principles of parasite
control and treatment
Parasitology - Ruminants
• Economic Losses
– Poor ADG
– Abortion
– Decreased conception
rates
– Death
• Public Health
– Zoonosis
Reasons For Economic Losses
-Producer Unaware of parasite
damage
• parasite-related losses ~ more
than $100 million
- Timing & Frequency of treatments
-Choice of dewormer
-Parasites have greatest impact on
high producing animals.
What is ruminants Parasitism?
• It is a herd disease
• It is a production disease
• It develops during grazing
• 99% of all pastures contaminated
Level of Parasitism Related To
• Age of animals
• Pasture contamination level
• Stocking rate of animals
• Grazing environment & Weather
• Immune status of animals
Definition
• Types of relationships between organism and
host
– Commensal ‐ one benefits without harming the
other
– Mutualism ‐ both participants benefit
– Parasitism ‐ one benefits at the expense of the
other
Definition
• Endoparasite ‐
internal infection
• Ectoparasite ‐
external infestation
• Zoonotic infection ‐
transmission of an
infection from
animals to humans
Definition
• Life cycle ‐ from the start of one generation to
the start of the next
– Direct ‐ completion of life cycle requires a
single host
– Indirect ‐ completion of life cycle requires
greater than one host
Direct Lifecycle
Indirect Lifecycle
Definition
• Definitive Host ‐ where sexual reproduction of
parasite occurs
• Intermediate Host ‐ required to complete a
developmental phase in the parasites life‐cycle,
excluding sexual reproduction
• Pre‐patent Period ‐ time from infection of definitive
host to the production of parasite offspring
Strategy For Lactating Cows
• Decrease milk production in early lactation
• Risk assessment
• Design deworming program
1.- High Parasite
Contamination Level
• Cows grazing pasture during lactation
• When rotational grazing is practiced
2. Moderate Parasite
Contamination Level
• Cows grazing pasture only during dry period
• Cows with access to an exercise lot only (with
some grass)
Low Parasite
Contamination Level
• Cows with access to dirt dry lot
4. Extremely Low Parasite
Contamination Level
• Cows in total confinement
• Cows on a concrete dry lot
Parasite – Indications
Purpose of the tests
• Fecal smear detection of certain protozoan trophozoites
• Fecal Float
• Fecal Sedimentation
• Comparison of techniques
Modified Wisconsin Sugar Flotation
Method
Technique
• Samples can be stored if
refrigerated
• Sugar solution
– One pound of sugar.
– Add to 12 oz(355cc) of hot
water.
• Slides can be refrigerated
for reading later
Materials
• Sugar solution & dispensing
syringe
• Tea strainer
• 3/5 oz dixie cups
• Tongue depressors
• Taper bottom 15cc tubes
• Test tube rack
• Microscope slides & 22x22
mm cover slips
Modified Wisconsin Sugar Flotation
Method
Add 15 - 17 cc sugar
solution to sample
Modified Wisconsin Sugar Flotation
Method
Place 3 - 5 grams of
fecal material into a 3
oz paper cup
(About a thimble full)
Modified Wisconsin Sugar Flotation
Method
Stir solution & fecal
sample to an even
consistency.
Modified Wisconsin Sugar Flotation
Method
Stir solution & fecal
sample to an even
consistency.
Modified Wisconsin Sugar Flotation
Method
Use a tongue depressor,
press as much material
through strainer as
possible.
Modified Wisconsin Sugar Flotation
Method
1. Pour into 15cc taper
bottom centrifuge tube.
2. Centrifuge in swinging
arm centrifuge at 900
rpm for 5 – 7 minutes.
Modified Wisconsin Sugar Flotation
Method
1. Place tube in rack and top
off with sugar solution to
form a meniscus.
2. Place 22x22 mm
cover slip on tube
and leave in place
for 2 - 4 minutes.
Modified Wisconsin Sugar Flotation
Method
Lift cover slip upward
& place on slide
Modified Wisconsin Sugar Flotation
Method
Use microscope to
scan entire cover slip
for egg count
TAXONOMY
KINGDOM
PHYLUM
CLASS
ORDER
SUPERFAMILY
FAMILY
SUBFAMILY
GENUS
SPECIES
Order
Superfamily
Comments
Strongylida
Trichostrongyloidea
Strongyloidea
Ancylostomatoidea
Metastrongyloidea
"Bursate" nematodes
Ascaridida
Ascaridoidea
Oxyurida
Oxyuroidea
Rhabditida
Rhabditoidea
Spirurida
Spiruroidea
Thelazioidea
Filarioidea
Habronematoidea
Enoplida
Trichuroidea
(Trichinelloidea)
Dioctophymatoidea
"Non-bursate"
nematodes
Parasite – Fecal flotation - Nematodes
• Strongylida:
• Enoplida:
Trichuridae
– Trichostrongylidae
• Haemonchus placei / contortus: Barberpole/
– Trichuris Ovis:
wire worm
whipworms
• Ostertagi Ostertagi: Brown stomach worm
– Capillaria spp.
• Trichostrongylus axei: Bankrupt worm/
• Rhabditida:
small stomach worm
Rhabditoidea
• Trichostrongylus colubriformis: Hair worm/
– Strongyloides
black scour worm
papilosus:
• Cooperia spp: Cattle bankrupt worm
threadworm
• Nematodirus spp: Thin necked intestinal
• Spirurida
worm
– Strongylidae
– Gongylonema
pulchrum:
• Oesphagostomum radiatum: nodular worm
Esophageal worm
– Ancyclostomatoidea
• Bunostomum phlebotomum: hookworms
Parasite – Fecal flotation
• CESTODES
– Monieza benedeni
• PROTOZOA
– Eimeria spp: Coccidia
– Cryptosporidium spp.
Moniezia expansa,egg. Courtesy of
Merial
Parasite – Fecal Sedimentation - Trematode
– Fasciola hepatica:
common liver fluke
Paramphistomum sp: rumen fluke
Parasite - Dx
Baerman Technique
• Strongylida:
– Trichostrongylidae
• Dictyocaulus
Viviparous: lung
worm
• Serological test/ necropsy
– CESTODES
• Taenia saginata: Beef measles
• Blood smears
– Protozoa
• Babesia bigemina
• Mff
– Nematodes:
• Onchocera spp.: skin nodular
worm
• Setaria cervi: Abdominal
worm
Common Parasites
Definition
• Types of parasites
– Nematodes (phylum nemathelminthes)‐
round worms
– Cestodes (phylum platyhelminthes) ‐ flat
worms
– Trematodes (phylum platyhelminthes) ‐
flukes
– Protozoa (phylum protozoa) ‐ single‐celled
eukaryotes
Nematodes
• Adult worms
– male and female
– range in size from large to microscopic
• Eggs →Larvae (stage 1‐4) →Adult
– Most have direct life cycles
– Most transmitted as infective larvae on
pasture
• GI tract and lungs as adults
GI Nematodes
• ~ 11 Genera, Many Species
• Sites
– abomasum, small intestine, cecum, and large
intestine
• Most ruminants = chronic infections
• Production losses and clinical disease are
proportional to severity of infection
GI Nematodes – Hot complex
• Haemonchus contortus or placei
– 1” (2 - 3 cm)
– Abomasum of small ruminants
– feeds on blood
– Clinical signs
• anemia
• death
Haemonchus placei, eggs. Courtesy of
Dr. Dietrich Barth, Merial
Clinical signs Haemonchus
• Calf is in poor condition
with ‘bottle jaw’ due to
hypoproteinemia and
anemia.
• It is massive direct
damage, usually late
winter.
Adults in the abomasum.
Barberpole worm
GI Nematodes
• Ostertagia ostertagi (brown stomach worm)
– 1/2” (1 cm) adult worm; abomasum
– most serious impact on calves
– disrupt gastric acid secretion
– Clinical signs
• diarrhea
• ill‐thrift
• poor feed conversion
Ostertagia ostertagi
GI Nematodes
• Trichostrongylus axei
– “Bankrupt worm”
– Adults ~1/4” (4‐8
mm); abomasum
– Clinical signs
–
–
–
–
Diarrhea
dehydration
bottle jaw
emaciation
GI Nematodes
• Cooperia spp.
– “Bankrupt worm”
– Adults ~1/4” (4‐8
mm); SI
– Clinical signs
– Anorexia
– Decreased growth
– Eggs are smaller than
strongyles
GI Nematodes
• Nematodirus spp.
– “Thin necked
intestinal worms”
– N. battus is more
pathogenic
– SI
– Diarrhea, Anorexia
B = typical strongyle egg
GI Nematodes
– Strongylidae
• Oesphagostomum radiatum:
nodular worm
• SI, cecum, colon
• anorexia; severe, constant,
dark, persistent, fetid
diarrhea; weight loss; and
death
• Adults: cysts in GI
– Ancyclostomatoidea
• Bunostomum phlebotomum:
hookworms
• SI
• Larger than strongyle
eggs
• Diarrhea, anemia,
weight loss, death –
young animals
GI Nematodes
• Enoplida: Trichuridae
– Trichuris Ovis: whipworms
– Cecum, LI
– In heavy infections, dark
feces, anemia, and anorexia
• Rhabditida: Rhabditoidea
– Strongyloides papilosus:
threadworm
– SI
– Smaller eggs
– Dairy calves
– intermittent diarrhea, loss of
appetite and weight, and
sometimes blood and mucus
in the feces
GI Nematodes
• Strongylida:
– Trichostrongylidae
• Dictyocaulus
Viviparous: lung
worm
• SI, lung
• Tachypnea, to severe
persistent coughing
and dyspnea and even
failure, weight loss,
reduced milk yields
(Photo by Dr. Perry Habecker,
Univ. Pennsylvania
Platyhelminthes (flatworms)
• Hermaphroditic
• Intermediate host (indirect life cycle)
• Flattened appearance
• Tapeworms (Cestodes)
• Flukes (Trematodes)
Tapeworms (cestodes)
• Adult worms few inches to 15 yards long
• Segmented worms with attached head
(scolex)
• Ruminants = intermediate host for canids and
humans
• Ruminants eat eggs passed in feces of canids
or people
Tapeworms (cestodes)
• Cysts in carcass, pea‐size to grape‐size (beef
measles)
• People/canids infected by eating encysted
beef
• Carcass condemnation
• ID, WA feedlots ‐ cattle infected with beef
tapeworm of man (Taenia saginata); 10% losses in
some feedlots
Taenia saginata
Dx: serological test/ necropsy
and no treatment
Liver Flukes (Trematodes)
• Fasciola hepatica (most
common); Fascioloides
magna
– Live in bile ducts as adults
– Aquatic snails = intermediate
host
– Clinical signs
• photosensitization
• reduced ADG
• hepatitis; clostridial dz
→death
– Condemned liver at slaughter
• $millions in losses
• Eggs: are heavy sedimentation is
recommended
Protozoa
• Single‐celled eukaryotes
• Amoeba; Ciliates (not discussed)
• Apicomplexa
– Eimeria, Cryptosporium, Toxoplasma,
Neospora, Babesia
• Flagellates
– Tritrichomonas, Giardia
Apicomplexa
• Intracellular protozoa
• Coccidia
– Sexual reproduction in
intestine → oocysts in
feces → definitive
(direct) host or
intermediate (indirect)
host
Eimeria
• Direct life‐cycle (all ruminants)
• Invade intestinal epithelium
– destruction of epithelial cells
– disruption of intestinal function
• Clinical signs
– acute and chronic disease
– watery and/or hematochezia
– decreased ADG → clinical
disease → death
– young >> adult
Cryptosporidium parvum
• Apicomplexa
• Similar to Eimeria
• Clinical signs
– diarrhea 1‐2 week old
calves
– disease severity varies
• Zoonotic: – particularly
with
immunocompromised
host
Toxoplasma gondii
• Indirect life‐cycle
• Cat = definitive host
– oocysts shed in cat feces
• Ruminants = intermediate
host
– tissue cysts
• Transmission to developing
foetus
– abortion
• Zoonotic
Neospora caninum
• Indirect life‐cycle
• Dog = intermediate host
• Clinical signs
– abortion
– neurologic disease in
calves born alive
Flagellates
• Mastigophora (flagellates that move with a
whip)
• Extracellular parasites
• One or more flagella ‐ assist with movement
• Divide by binary fission
• Example
– Tritrichomonas foetus
Tritrichomonas foetus
• Simple reproduction
– binary fission
– trophozoite is only stage
• Venereal disease of cattle
(bull = carrier)
• Clinical signs
– early abortion
– pyometra
– significant $losses due to
decreased preg. rate
References
• Large animal clinical procedures for veterinary technicians,
Elizabeth A. Hanie, 2006
• http://www.caes.uga.edu/publications/pubDetail.cfm?pk_ID=6
196
• http://courses.cals.uidaho.edu/avs/avs471/Lectures/Lectures%
202010/Lecture%20Parasites%20notes.pdf
• http://cal.vet.upenn.edu/projects/dxendopar/parasitepages/trem
atodes/Fhepatica.htm
• http://cal.vet.upenn.edu/projects/dxendopar/index.html#fecal
• http://www.sheepandgoat.com/HairSheepWorkshop/parasitism
.html
• http://cal.vet.upenn.edu/projects/merial/Nematodes/Table1.ht
m
References
• http://www.vetmed.wisc.edu/pbs/vetpara/tutori
al2.html
• http://www.merckvetmanual.com/mvm/index.j
sp?cfile=htm/bc/toc_22400.htm
• http://instruction.cvhs.okstate.edu/jcfox/htdocs
/clinpara/lst41_50.htm