HELMINTH PARASITES

PWAVENO HULADEINO BAMAIYI, PhD

SENIOR LECTURER

FACULTY OF VETERINARY MEDICINE

UNIVERSITI MALAYSIA KELANTAN

PARASITE TAXONOMY

PARASITIC WORMS

• Phylum-Platyhelminthes (“flatworms”, “flukes” and “tapeworms”)

• Phylum-Nemathelminthes (“roundworms”)

• Phylum-Acanthocephala (“thorny-headed worms”)

• Phylum-Annelida (“segmented worms”, “night crawlers”)

• Phylum-Arthropoda (“tongue worms”)

Fasciola spp.

1. F. hepatica

2. F. gigantica

Scientific Classification

Kingdom: Animalia

Phylum: Platyhelminthes

Class: Trematoda

Subclass: Digenea

Order Echinostomida

Family: Fasciolidea

Genus: Fasciola

Species:hepatica & gigantica

General Information

- Commonly known as liver fluke

- A parasitic flatworm

Geographical Distribution

- Found in Rural areas of temperate and tropical regions

- Especially located in regions with cattle and sheep herding

- Found on every continent with nearly 180 million people at risk and an estimated 2.4 million people already infected worldwide.

Transmission

- Occurs through the ingestion of raw, fresh water vegetation

- Plants become exposed to the metacercariae when the body of water that the vegetation is growing in becomes contaminated by eggs in the fecal mater of the infested host

- A form of infection known as halzoun (in the Middle East) is contracted by eating the raw liver of an infected animal

Morphology

- Adult has a flat leaflike body

- About 20-30 mm long by 8-15 mm wide

- Has an anterior elongation where oral and ventral suckers are located

- Intestines are very branched

Hosts

- Cattle

- Sheep

- Goats

- Sometimes humans

Life Cycle

Life Cycle (Cont’d)

- The adult F. hepatica lives in bile ducts of the host’s liver

- Begin to produce eggs 2-4 months after initial infection

- Eggs pass down the bile duct through gastrointestinal tract and are released in the hosts feces

- Require water of temperature above 10 C to hatch

- The egg hatches and releases miracidiae within two weeks

- These newly hatched miracidiae must find a Lymanae snail host within 24 of hatching or they will die

Life Cycle (Cont’d)

- Inside the Lymanaea miracidium loses its cilia and develops into a sporocyst

- Each sporocyst develops into a redia which then burst the sporocyst and migrate to the hepato-pancreas of the snail

- Redia then develop into cercariae - Cercariae attach to plant matter and encyst,

forming metacercariae which is the infective form of the fluke

- Mammalian host consumes the vegetation with the metacercariae which then excyst in the small intestine

Life Cycle (Cont’d)

- Metacercariae burrow through the intestinal wall, move through the peritoneal cavity and enter the liver parenchyma

- Immature flukes migrate through the liver patanchyma for 6-8 weeks giving rise to acute symptoms

- Once mature they settle in the bile ducts and begin to produce their own eggs after about a month.

http://www.cdfound.to.it/hTML/fh2a.htm

Four Symptomatic Patterns

- Acute Phase

- Cronic Phase

- Halzoun

- Ectopic Infection

Acute Phase

- Rarely seen in humans

- Fever, tender hepatomegaly, and abdominal pain are frequent symptoms.

- Vomiting, diarrhea, and anemia may also be present

Chronic Phase

- More common in human population

- Symptoms include: bilary cholic, abdominal pain, tender hepatomegaly, and jaundice

- In children: severe anemia is common

- Inflammation of the bile ducts eventually leads to fibrosis and a condition called “pipestem liver”

- Severe infections can lead to death

Halzoun & Ectopic Infection

- Occurs when an individual consumes infected raw liver

- The adult worms can cause considerable pain, edema, and bleeding that can interfere with respiration

- Adults can live in biliary ducts and cause symptoms for up to 10 years.

- In frequent, but can occur in peritoneal cavity, intestinal wall, lungs, subcutaneous tissue, and very rarely in other locations.

Diagnostic Tests

- Most widely used form of diagnosis is the directly observed presence of F. hepatica eggs either in a stool sample, duodenal aspirate or biliary aspirate

- Flukes do not begin to produce eggs until about 4 months after infection, so you cannot test the stool

- Prior to 4 months: serological tests can be used - FAST-ELISA (most popular)

- Ultrasound can be used to visualize adult flukes in the bile ducts

- CT scan can reveal burrow tracts made by the worms

Treatment

- Many countries use a 5-10 day course of oral bithionol at 30mg/kg body weight

- Triclabendazole is a preferred antihelmintic agent, but is unavailable in most countries.

- The resistance is rising to this drug

- Along with pharmaceutical therapy, surgery may be necessary in very extreme cases to clear the biliary tract

Control Methods

- Education

- Molluscicides: application of malluscicides to decrease the population of Lymnaea snails

- Chemotherapy

Review Questions

- 1. What is the average size of an adult F. hepatica?

a. 20 mm x 5mm

b. 30 mm x 13 mm

c. 10 mm x 5 mm

2. What continent can F. Hepatica be found?

a. Africa

b. Asia

c. America

d. All of the above

Review (Cont’d)

- 3. What is the most effective way to treat fascioliasis?

a. bithionol

b. flagyl

c. triclabendazole

References

• Sarah Richards and Max Karpyak

- “Fascioliasis” Retrieved: 2/19/2007 by Richards and Karpyak http://www.stanford.edu/class/humbio103/fascioliasis/Fasciola.htm

- “Fasciola hepatica.” Wikipedia, free encyclopedia. Retrieved: 2/19/2007 http://en.wikipedia.org/wiki/Fasciola_hepatica

- “Fasciola hepatica.” Retrieved: 2/19/2007 http://www.cdfound.to.it/html/fas1.htm

Trichostrongylus spp.

• Morphology:

Zoonoses spp.

• T. axei

• T. orientalis

• T. probolorus

• T. skirjabini

• T. colubriformis

• ………………

Definitive host

Trichostrongylus colubriformis third-stage larva obtained after culture of faeces

from an artificially infected sheep.

Life cycle Prepatent period: 2-3 weeks

Trich. spicules

•

•

••

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

Moniezia spp.

Introduction：

They are found in the small intestine of ruminants, like cattle,sheep,and camel,

especially in lamb and calf.

Monieziosis is a cestodiasis caused by Moniezia sp. including Moniezia expansa and M.benedni

M.expansa :The more common in sheep and goat than in cattle

M.benedni: The more common in cattle than in sheep and goat

Moniezia spp. have unarmed scolices with four large sucker and very wide segments with bilateral genitalia.

M. expansa

scolices

M. benedeni

Morphology

Interproglottidal glands at the posterior margin of each segment extend the full width of M. expansa but occupy only the midzone of the M. benedeni segment.

Difference of M. expansa and M. benedeni

1 2

Characteristic of eggs The egg of Moniezia spp. found

in cattle feces is

one of the few eggs that appears square, and internally the pear-shaped (pyriform apparatus) characterristic of anoplocephalid eggs can be seen.

Pyriform apparatus

Life cycle of Moniezia spp

Definitive host: ruminants. Site of infection: small intestine Intermediate host: Forage mites Infective stage: cysticercoid Prepatent preiod : month 3

Moniezia is living in small intestine of ruminant. The definitive host leaves the gravid proglottids and eggs in the feces . The oncosphere migrate into the body cavity of the mite where they develop into cysticercoids for at least 40 d and infection of the definitive host is by ingestion of infected mites during grazing. The prepatent preiod is approximately 45~60 d, but the adult worms appear to be short-lived, persist for only three months.

Epidemiology

The Monieziosis distribbution is world-wide.

Moniezia spp. are the commonest in young animals, and are of low pathogenicity

Their incidence shows a seasonal fluctuation, coinciding with the active period of the vectors.

Symptoms

When there are lots of Moniezia, the intestines will become enteremphraxia even have been ruptured

The toxin of parasite cause young animals being neurosis, including walking in circles spasm, non-food mastication.

clinical symptoms：

Decreased appetite, emaciation, anaemia, listless, diarrhea,

gravid proglottid in feces

Lesions

The disease can make corpse become thin , the colour of muscle turn light and make exudates in abdomen increase.

Others: enteremphraxia, contortion,hemorrhage

Diagnosis is based on a history of residence in

an endemic area and symptoms.

Fecal examination:

When there is no proglottids in feces ,using the flotation method

Diagnosis

Treatment

1.Bithionol: 50mg per kilogram of body weight for cattle, or 75mg to 100mg for sheep, P.O.

2.Niclosamide:50mg per kilogram of body weight for cattle, or 60mg to 75mg for sheep, P.O.

3.Mebendazole：10mg per kilogram of body weight for cattle, or 15mg for sheep, P.O.

4.Albendazole:5mg per kilogram of body weight for cattle, or 20mg for sheep, P.O.

5.Praziquantel：5mg to 10mg per kilogram of body weight for cattle, or 10mg to 15mg for sheep, P.O

Prevention

• 1. Deworm before adult stage • 2.Harmless disposal of feces • 3.Improvement of breeding and management ploughing and reseeding to avoid pasturing in the early

morning or at dust, when the peak of forage mite activities regularly testing forage mite within the pasture

PARASITES OF SWINE (PIGS)

Introductory Recaps

• Parasitism occurs in varying degrees:

1. parasitiasis- here the parasite is present in or on the animal host, and is potentially pathogenic but the animal does not show any outward clinical signs of disease

Introductory Recaps cont.

• Parasitism occurs in varying degrees:

1. parasitosis- here the parasite is present in or on the body of the animal and does produce obvious injury or harm to the host manifesting in clinical signs of parasitism.

Introductory Recaps cont.

LINNAEAN CLASSIFICATION SCHEME:

1. Kingdom

2. Phylum

3. Class

4. Order

5. Family

6. Genus

7. Species

Mnemonic: “King Philip came over for good spagheti”

Local pigs

Internal Parasites

• The large roundworm (ascarid) is the most common internal parasite of swine

• Other roundworms include: stomach worms, intestinal treadworms, kidney worms, lungworms and nodular worms

• Symptoms of worm infestation include: poor growth, thin rough hair coat, diarrhea and coughing

Internal parasites continued

• Ascarid migration increases susceptibility to pneumonia

• Ascarid migration results in white spots in the liver

• Worms can be controlled by the use of anthelmintics and good sanitation

Common vs Technical Terms for Internal Parasites

• Large roundworms = Ascarid

• Stomach worms = Hydrostrongylus

• Intestinal threadworms = Strongyloides

• Kidney worms = Stephanurus

• Lungworms = Metastrongylus

• Nodular worms = Oesophagostomum

• Whipworms = Trichuris

Internal parasites continued

• Some common dewormers include:

• Atgard = Dichlorvos (feed)

• Banminth = Pyrantel Tartrate (feed)

• Tramisol = Levamisole (feed or water)

• Ivermectin = Ivomec (injectable

Endoparasites

Ascaris suum - roundworm • Ascariasis

• PPP: 8 weeks

• CS: unthriftiness, failure to gain weight, rough hair coat, pendulous abdomen, chronic paroxysmal coughing and occasionally, abdominal expiratory dyspnea (“thumping”).

• Dx: fecal flotation, worms – intestines, milk spots - liver

• Tx: Ivermectin, fenbendazole, dichlorvos, doramectin, hygromycin, levamisole, piperazine

• ZOONOTIC: ingestion of eggs

Picture Credit: http://caltest.vet.upenn.edu/merial/swine/swine_6.htm (original image no longer available) Image: Ascaris suum in small intestine of pig.

Figure 6-48 Characteristic ovum of Ascaris suum, the swine ascarid or the large intestinal roundworm of pigs. The eggs are oval and

golden brown, with a thick, albuminous shell bearing prominent projections. They measure 70 to 89 µm by 37 to 40 µm.

(From Hendrix CM, Robinson E: Diagnostic parasitology for veterinary technicians, ed 3, St Louis, 2006, Mosby.)

Trichuris suis - whipworm

• PPP: 6 weeks

• CS: diarrhea, unthriftiness

• Dx: fecal flotation, adults - LI

• Tx: Ivermectin, dichlorvos, hygromycin, levamisole, fenbendazole

Strongyloides ransomi - threadworm

• PPP: 7 days

• CS: severe diarrhea: 10 – 14 days with high mortality

• Dx: fecal flotation

• Tx: Ivermectin, dichlorvos, hygromycin, fenbendazole

Eimeria spp. - coccidia

• PPP: 14 days

• CS: piglets: enterocolitis

• Dx: fecal flotation

• Tx: piglets – sulfamethazine; sows - decoquinate

Isospora suis - coccidia

• PPP: 14 days

• CS: piglets: 6 – 21 days, stunted, mortality

• Dx: fecal flotation

• Tx: piglets – sulfamethazine; sows - decoquinate

Figure 6-52 Oocyst of Isospora suis.

(From Hendrix CM, Robinson E: Diagnostic parasitology for veterinary technicians, ed 3, St Louis, 2006, Mosby.)

Metastrongylus spp. – Lung worm

• PPP: 1 month

• CS: coughing, poor growth

• Dx: fecal flotation; Adults - LI

• Tx: Ivermectin, doramectin, fenbendazole, levamisole

Lung of pig showing lesions caused by lungworm (Metastrongylus).

Oesophagostomum dentatum – nodular worm • PPP: 40 days

• CS: asymptomatic, nodules – gut: enteritis

• Dx: fecal flotation; Adults – LI

• Condemnation intestine

• Tx: Ivermectin, doramectin, fenbendazole, levamisole, pyrantel tartrate, hygromycin, dichlorvos

Ascarops strongylina – stomach worm

• PPP: 6 weeks

– Dung beetle: intermediate host

• CS: nonpathogenic

• Dx: fecal sedimentation; Adults – stomach

• Tx: Ivermectin, doramectin, dichlorvos

Ascarops strongylina, egg. Courtesy of Dr. Dietrich Barth, Merial

Stephanurus dentatus – kidney worm

• PPP: 8 – 16 months

• CS: loss of weight, condemnation organs – migrating larvae

• Dx: eggs – urine sedimentation; adults – cysts perirenal fat and pelvis of kidney; larvae - liver

• Tx: Ivermectin, doramectin

Figure 6-53 Egg of Stephanurus dentatus, the swine kidney worm. These eggs are strongyle type; that is, they are oval, thin-shelled

eggs containing 4 to 16 cells and measuring 90 to 120 µm by 43 to 70 µm. Eggs can be recovered from the urine by urine

sedimentation.

(From Hendrix CM, Robinson E: Diagnostic parasitology for veterinary technicians, ed 3, St Louis, 2006, Mosby.)

Trichinella spiralis – Trichina worm

• LC: 4 days; 20 days for larvae to be infective

• Dx: necopsy

• Tx: none, don’t feed uncooked garbage to pigs, cook all meat to recommended temperature and time

• ZOONOTIC: ingestion of raw meat

Taenia solium – Pork tapeworm

• Taeniasis, cysticercosis

• LC: 2 months, swine intermediate host

• Dx: necopsy – cysterci; serologic test – humans/ pigs; eggs feces - humans

• Tx: none, don’t feed human feces, cook all meat to recommended temperature and time

• ZOONOTIC: ingestion of raw meat

Taenia solium cysticerci in the masseter muscle of an adult pig.

(Photo courtesy of Dr. A. Lee Willingham III, WHO/FAO Collaborating Center for Parasitic Zoonoses, Denmark

Balantidium coli

• Protozoa

• LC: 6 – 14 days

• CS: mild – severe enteritis

• Dx: necopsy - LI ; fecal flotation

• Tx: Tetracycline, metronidazole

• ZOONOTIC

Figure 6-51 A, Balantidium coli of swine in histopathologic section. This photomicrograph was taken at low magnification. Note that

B. coli is quite large and easily visible (arrows). B, B. coli of swine in histopathologic section. This photomicrograph was taken at

higher magnification than A.

(From Hendrix CM, Robinson E: Diagnostic parasitology for veterinary technicians, ed 3, St Louis, 2006, Mosby.)

Figure 6-50 Trophozoite stage of Balantidium coli, the “ciliated protozoan” found in the large intestine of swine. The trophozoites

may be 150 by 120 µm, with a sausage- to kidney-shaped macronucleus. They are covered with numerous rows of cilia and move

about the microscopic field with lively motility. The cyst is spherical to ovoid and 40 to 60 µm in diameter, with a slight greenish-yellow

color.

(From Hendrix CM, Robinson E: Diagnostic parasitology for veterinary technicians, ed 3, St Louis, 2006, Mosby.)

Treatments

External Parasites

• Lice (hog louse)

• Are blood suckers. Approximately ¼” long

• Result in economic loss due to reduced performance

• Control by use of insecticides

• Insecticides available as a spray, pour-on, dust, granule or injectible

Mange

• Caused by microscopic mites that burrow beneath the skin.

• Causes severe itching

• Will reduce swine performance

• Control by the use of insecticides.

• Ivermectin is the insecticide of choice

ECTOPARASITES

Sarcoptes scabiei – Mange mite

• LC: 3 weeks

• CS: pruritis and papules.

• Dx: Skin scrapings

• Tx: Ivermectin

• ZOONOTIC

Haematopinus suis – Hog Louse

• Pediculosis, host specific, contagious

• LC: 3 weeks

• CS: pruritis

• Dx: check skin

• Tx: Amitraz, Ivermectin

• Prevention: Hygiene

Figure 7-4 A, Thousands of nits can be cemented by female lice to the haircoat of domesticated animals. This calf’s tail contains

thousands of nits. B, Pediculosis can be defined as infestation by either chewing or sucking lice, in this case, Haematopinus suis

infestation in a pig. C, Appearance of operculated nits viewed by compound microscope.

(From Hendrix CM, Robinson E: Diagnostic parasitology for veterinary technicians, ed 3, St Louis, 2006, Mosby.)

References

• K Holtgrew-Bohling , Large Animal Clinical Procedures for Veterinary Technicians, 2nd Edition, Mosby, 2012, ISBN: 97803223077323

• Laboratory procedures for Veterinary Technicians, 5th edition, 2007, Hendrix C.M; Sirois M.

• http://vetmed.iastate.edu/vdpam/new-vdpam-employees/food-supply-veterinary-medicine/swine/swine-diseases

• http://www.flockandherd.net.au/other/reader/sarcoptes%20pigs.html

• http://www.ent.iastate.edu/imagegallery/

• http://nematode.net/NN3_frontpage.cgi?navbar_selection=speciestable&subnav_selection=Ascaris_suum

References

• http://www.ecvpath.org/october-2008/

• http://cal.vet.upenn.edu/projects/dxendopar/parasitepages/hooklungstrongyloides/s_ransomi.html

• http://parasitology.cvm.ncsu.edu/quiz/swine/exam2/swinequizEA.php

• http://uk.merial.com/producers/swine/woe/woe_04.asp

• http://vetpda.ucdavis.edu/parasitolog/Parasite.cfm?ID=94

• http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/22605.htm

• http://www.wormbook.org/chapters/www_genomesTrichinella/genomesTrichinella.html

• http://www.cesa.life.ku.dk/Cysticercosis.aspx

Parasites of Dogs and Cats

Arthropods and Protozoa

Insects

• Trichodectes canis (Biting louse)

• Linognathus setosus (Sucking louse)

• Ctenocephalides (Flea)

• Cuterebra (Rodent Bot Fly)

Trichodectes canis (Biting louse)

• Found as felicola sustratus in the cat

• Cause roughened hair coat, itching and dermatitis

• May act as intermediate host to Dipylidium caninum

Linognathus setosus (Sucking louse of dogs)

• Causes skin irritation, itching, dermatitis, alopecia, anemia, roughened hair coat

• Usually transmitted by direct contact, but all life stages may be transmitted by fomites

• Are species specific

Ctenocephalides (Flea)

• Infest dogs and cats

• Vector for Dipylidium caninum, tularemia, plague, etc.

• Die at temperatures below 20 F for 48 hours or at temperatures above 120 for several days

• Over 200 species of fleas worldwide

• Severe infestations can cause anemia

Cuterebra (Rodent Bot Fly)

• Infests rodents, companion animals and occasionally humans

• Larval stage that infests skin

• Acts as an irritant

• Migration may be fatal

• Have a cutaneous lump with a breathing hole

• Use care when extracting as crushing larva may result in anaphylaxis

Arachnids

• Sarcoptes scabiei (Scabies)

• Demodex canis (Demodectic mange)

• Otodectes cynotis (Ear mites)

• Cheyletiella (Walking dander mite)

• Rhipicephalus sanguineus (Brown dog tick)

• Dermacentor variabilis (American Dog tick)

• Amblyomma americanum (Lone Star tick)

Sarcoptes Scabiei (Scabies)

• Found as Notoedres cati in cats

• Causes intense itching, dry and thickened skin.

• Is contagious to humans and other pets

• Mites burrow under the skin so may be difficult to diagnose

• Diagnose through a skin scraping

• Usually have “ventral blowout”

Demodex canis (Demodectic Mange)

• Rare in cats

• Causes areas of alopecia on head, neck, forelimbs.

• Can be localized or generalized.

• Diagnosed with skin scraping.

• Is not contagious

• Small numbers considered normal on skin flora

• Genetic predisposition

Otodectes cynotis (Ear mites)

• Intense pruritis of the ear canal.

• Can be found on any area of the body

• Feed on epidermal debris and are easily transmitted

Cheyletiella (Walking Dander mite)

• Causes mild alopecia and pruritis

• May cause dermatitis in humans

• Ingest keratin debris and tissue fluids

• Have enormous hook like accessory mouthparts

• Are visible to the naked eye

Rhipicephalus sanuineus (Brown dog tick)

• Vector for canine babesiosis and canine ehrlichiosis

• May cause anemia or tick paralysis when found in large numbers

Dermacentor Variabilis (American Dog Tick)

• Feeds on small mammals but can also feed on dogs and humans

• Vector for Rocky Mountain Spotted Fever, tularemia, and can cause tick paralysis in animals and humans

Anblyomma americanum (Lone Star tick)

• Gets name from white spot on apex of scutum

• Feeds on animals and humans

• May be vector for Rocky Mountain Spotted Fever and tularemia.

• Vector of Ehrlichia

Protozoa

• Neospora caninum (Neospora)

• Isopora (Coccidia)

• Giardia canis (Giardia)

• Toxoplasma gondii (Toxo)

• Sarcocystis (Sarcocystis)

Neospora caninum (Neospora)

• Transmitted transplacentally or orally

• May cause ascending paralysis

• A type of coccidia

Isopora (Coccidia)

• Diarrhea in kittens and puppies.

• May be fatal

• One of most commonly diagnosed protozan disorders in puppies and kittens.

• Rarely a problem in mature animals

• Very small in comparison to other parasites

Toxoplasma gondii (Toxo)

• May cause transient diarrhea in cats

• Highly pathogenic to humans, especially fetus in utero

Sarcocystis

• Not very pathogenic in cats

• Very pathogenic in sheep

Giardia canis (Giardia)

• Causes diarrhea

• Occur as cysts or trophozoites in fecal flotation.

• May also be tested for through a snap test now available.