veterinary helminthology

VETERINARY VETERINARY HELMINTHOLOGYHELMINTHOLOGY

TAPEWORM/ CESTODESTAPEWORM/ CESTODES

General Characteristics:General Characteristics:1. ribbon-like and dorsoventrally flattened1. ribbon-like and dorsoventrally flattened

2. most of the show indirect types of life cycle. The exceptional type of 2. most of the show indirect types of life cycle. The exceptional type of life cycle is found in life cycle is found in Hymenolepis sppHymenolepis spp where direct and indirect where direct and indirect

types are found.types are found. 3. they are hermaphrodite3. they are hermaphrodite

4. cysts or bladderworms are intermediate or larval stage of the 4. cysts or bladderworms are intermediate or larval stage of the parasiteparasite

5. the final host gets infection by ingestion of intermediate host or flesh 5. the final host gets infection by ingestion of intermediate host or flesh of intermediate host containing the bladder wormsof intermediate host containing the bladder worms

6. the body can be divided into three broad parts 6. the body can be divided into three broad parts

Head/ ScolexHead/ Scolex -very minute as compared to other parts-very minute as compared to other parts

-shape varies which may be roughly triangular,ball shaped or round-shape varies which may be roughly triangular,ball shaped or round

-there is presence of sucker (armed or unarmed ) which is not used -there is presence of sucker (armed or unarmed ) which is not used for taking food but used as apertures for attachmentfor taking food but used as apertures for attachment

-anteriorly there is structure called rostellum-anteriorly there is structure called rostellum

NeckNeck -immediately behind the head and without any segment-immediately behind the head and without any segment

-segmentation starts here-segmentation starts here

Body Body -area is completely segmented-area is completely segmented

Three types of segments are present:Three types of segments are present:

IMMATURE- the reproductive system and eggs are absentIMMATURE- the reproductive system and eggs are absent

MATURE- completely developed reproductive system MATURE- completely developed reproductive system

GRAVID- reproductive system is replaced by the eggs GRAVID- reproductive system is replaced by the eggs

- either detached from the parasite or its disintegrated and - either detached from the parasite or its disintegrated and the eggs are expelled outthe eggs are expelled out

Eggs:Eggs:

-have basic structure comprising oncosphere or hexacanth embryo, -have basic structure comprising oncosphere or hexacanth embryo, a striated shell or embryophore and a delicate membranea striated shell or embryophore and a delicate membrane

-the following are the events which occur during biological -the following are the events which occur during biological development:development:

a. Eggs are expelled out from the gravid segmenta. Eggs are expelled out from the gravid segment

b. the eggs are ingested by the intermediate hosts and hatching b. the eggs are ingested by the intermediate hosts and hatching occurs in the intermediate host or hatch in the environment occurs in the intermediate host or hatch in the environment ( Cotyloda) ( Cotyloda)

-metacestodes / bladderworms / cyst / larval stages are formed in the -metacestodes / bladderworms / cyst / larval stages are formed in the intermediate hostintermediate host

-final host gets the infection by ingestion of the intermediate host or the -final host gets the infection by ingestion of the intermediate host or the muscles and flesh containing the cysts or bladderwormsmuscles and flesh containing the cysts or bladderworms

Poultry TapewormPoultry TapewormGenus RaillietinaGenus Raillietina

--small to medium-sized tapeworm that inhabit the small intestine small to medium-sized tapeworm that inhabit the small intestine

-cosmopolitan in distribution-cosmopolitan in distribution

Species:Species:

R. cesticillus R. demerariensisR. cesticillus R. demerariensis

R. echidnobothridaR. echidnobothrida

R. tetragonaR. tetragona

R. asiaticaR. asiatica

R. celebensisR. celebensis

R. cesticillusR. cesticillus

Morphology:Morphology:

1. smaller (4-15 cm) than R. tetragona, R. echidnobothrida1. smaller (4-15 cm) than R. tetragona, R. echidnobothrida

2. broad rostellum which is armed with 400-500 hooks2. broad rostellum which is armed with 400-500 hooks

3. circular sucker is unarmed3. circular sucker is unarmed

4. egg capsule contains single egg4. egg capsule contains single egg

R. echidnobothridaR. echidnobothrida

MorphologyMorphology

1. size is 8.5-22 cm1. size is 8.5-22 cm

2. suckers are circular and surrounded by several rows of hooks2. suckers are circular and surrounded by several rows of hooks

3. rostellum is very small3. rostellum is very small

4. egg capsule contains multiple eggs4. egg capsule contains multiple eggs

R. tetragonaR. tetragona 1. 25 cm long and largest tapeworm in poultry1. 25 cm long and largest tapeworm in poultry

2. rostellum is small and possesses one or two rows of hooks 2. rostellum is small and possesses one or two rows of hooks

3. egg capsule contains multiple eggs3. egg capsule contains multiple eggs

4. sucker is oval and surrounded by several rows of hooks4. sucker is oval and surrounded by several rows of hooks

LIFE CYLCE:LIFE CYLCE:

eggegg

oncosphereoncosphere

cysticercoid ( infective stage )cysticercoid ( infective stage )

adultadult

Ants and Musca domestica acts as IH of R. tetragona and R. Ants and Musca domestica acts as IH of R. tetragona and R. echidnobothrida. The beetle acts as IH for R. cesticillusechidnobothrida. The beetle acts as IH for R. cesticillus

Pathogenesis:Pathogenesis:

1. nodule formation in the intestine by R. echidnobothrida1. nodule formation in the intestine by R. echidnobothrida

2. enteritis by R. tetragona and R. cesticillus2. enteritis by R. tetragona and R. cesticillus

Genus DavaineaGenus Davainea

D. proglottinaD. proglottina

D. meleagridisD. meleagridis


1. very small only several mm that’s why it is advised to take 1. very small only several mm that’s why it is advised to take mucosal scraping for its detectionmucosal scraping for its detection

2. has prominent rostellum armed with hammer-shaped hooks2. has prominent rostellum armed with hammer-shaped hooks

3. presence of single set of reproductive organ which alternates 3. presence of single set of reproductive organ which alternates regularlyregularly

4. has 4-9 segments4. has 4-9 segments

5. egg capsule contains single egg5. egg capsule contains single egg

Life cycle:Life cycle:EggEgg

OncosphereOncosphere

Cysticercoid in IH ( infective stage on ants or slugs )Cysticercoid in IH ( infective stage on ants or slugs )

AdultAdult

The gravid segments crawl out of the host. The gravid The gravid segments crawl out of the host. The gravid segments are actively motile and crawl onto the grass blade due to segments are actively motile and crawl onto the grass blade due to its phototactic nature. The eggs are released during the act of its phototactic nature. The eggs are released during the act of crawling. The eggs hatch after ingested by IH and cysticercoid is crawling. The eggs hatch after ingested by IH and cysticercoid is formed within a month. The final host gets the infection when the formed within a month. The final host gets the infection when the infected snails are ingested by the birds.infected snails are ingested by the birds.

Family Dipyliidae:Family Dipyliidae: Dipylidium caninum- double pored tapeworm of dogsDipylidium caninum- double pored tapeworm of dogs


1. head or scolex is pyriform in shaped having hooks characteristically 1. head or scolex is pyriform in shaped having hooks characteristically rose-thorn shapedrose-thorn shaped

2. presence of two sets of reproductive system like Moniezia spp2. presence of two sets of reproductive system like Moniezia spp

3. mature segments are cucumber seed shape3. mature segments are cucumber seed shape

LIFE CYCLE:LIFE CYCLE:

eggegg

onchosphereonchosphere

cystercercoid in IH ( flea C. canis, C. felis, T. canis, Pulex spp )cystercercoid in IH ( flea C. canis, C. felis, T. canis, Pulex spp )

adultadult

Gravid segments get detached from the adult tapeworm and crawl. Gravid segments get detached from the adult tapeworm and crawl. During crawling the eggs are released from the gravid segment. The During crawling the eggs are released from the gravid segment. The IH ingest the eggs and hatched in the gut and oncospheres are IH ingest the eggs and hatched in the gut and oncospheres are released and these migrate in the body cavity. A cysticercoid with released and these migrate in the body cavity. A cysticercoid with tail appendage is formed within few weeks. Final host gets the tail appendage is formed within few weeks. Final host gets the infection by ingestion of the infected IH.infection by ingestion of the infected IH.


1. sloughing, denudation of mucosa1. sloughing, denudation of mucosa

2. constant irritation of the anal sac resulting to anal pruritus2. constant irritation of the anal sac resulting to anal pruritus

3. intoxication due to absorption of the metabolites released by the 3. intoxication due to absorption of the metabolites released by the parasites which affects the nervous systemparasites which affects the nervous system

Diagnosis:Diagnosis:

1. examination of fecal sample1. examination of fecal sample

2. dragging anus over the ground or any hard objects 2. dragging anus over the ground or any hard objects

Family Anoplocephalidae: common cestodes of equineFamily Anoplocephalidae: common cestodes of equine Morphology:Morphology:

1. rostellum and hooks are present 1. rostellum and hooks are present

2. segments are noticeably broad\2. segments are noticeably broad\

3. presence of egg capsule or paruterine organ3. presence of egg capsule or paruterine organ

4. eggs have 3 coverings; the outermost formed by the vitelline gland, 4. eggs have 3 coverings; the outermost formed by the vitelline gland,

middle albuminous and inner chitinousmiddle albuminous and inner chitinous

5. eggs of many members bear a pear shaped structure called 5. eggs of many members bear a pear shaped structure called pyriform apparatuspyriform apparatus

Genera:Genera:

Anoplocephala MonieziaAnoplocephala Moniezia

Paranocephala CittotaeniaParanocephala Cittotaenia

PseudanocephalaPseudanocephala

Imporant species:Imporant species:

Anoplocephala Anoplocephala magnamagna

AnoplocephalaAnoplocephala

perfoliataperfoliata

PseudoanoplocephalPseudoanoplocephala mamillanaa mamillana

1. Largest cestode 1. Largest cestode found in the horse found in the horse found in SI and found in SI and stomachstomach

Small intestineSmall intestine Si and stomachSi and stomach

2. 80 cm long2. 80 cm long 1-8 cm 1-8 cm 0.6- 5 cm0.6- 5 cm

3. Testes are 3. Testes are arranged in rows. arranged in rows. The number of testes The number of testes are 400-500are 400-500

250 250 100100

4. Pyriform apparatus 4. Pyriform apparatus is not strong and is not strong and large large

Large and strongLarge and strong Large and srongLarge and srong

Lappets are absentLappets are absent presentpresent absentabsent


EggEgg

OnchosphereOnchosphere

Cysticercoid in IH ( mite)Cysticercoid in IH ( mite)

AdultAdult


A. perfoliata particularly affects the ileocecal orifices and they A. perfoliata particularly affects the ileocecal orifices and they produce depressed ulcers which is dasrk in color and may cause produce depressed ulcers which is dasrk in color and may cause perforation of SIperforation of SI

A. magna causes hemorrhagic enteritis obstruction of the intestinal A. magna causes hemorrhagic enteritis obstruction of the intestinal lumenlumen

P. mamillana less significantP. mamillana less significant

Family HymenolepididaeFamily Hymenolepididae

H. cariocaH. carioca H. diminutaH. diminuta H. nanaH. nana

dwarf tapewormdwarf tapeworm

1. 3-8 cm1. 3-8 cm 2-6 cm2-6 cm 7-80 cm7-80 cm

2. 500 segments2. 500 segments 500 segments500 segments Few segmentsFew segments

3. testes lie across 3. testes lie across the segmentthe segment

Testes are ovoidTestes are ovoid Testes lie in line and Testes lie in line and separated by the separated by the ovaryovary


eggegg


cysticercoid in IHcysticercoid in IH

adultadult

Family TaeniidaeFamily Taeniidae


1. large tapeworm1. large tapeworm

2. proglottids are rectangular2. proglottids are rectangular

3. rostellum may or may not be present3. rostellum may or may not be present

4. segments are longer and broader4. segments are longer and broader

5. uterus has median stem and lateral branches5. uterus has median stem and lateral branches

6. egg capsule is easily lost and the embryo pore is striated in appearnace6. egg capsule is easily lost and the embryo pore is striated in appearnace

Intermediate StageIntermediate Stage Intermediate hostIntermediate host

Taenia soliumTaenia solium Cysticercus cellulosaeCysticercus cellulosae pigpig

Taenia saginataTaenia saginata Cysticercus bovisCysticercus bovis cattlecattle

Taenia hydatigenaTaenia hydatigena Cysticercus tenuicollisCysticercus tenuicollis Sheep, ruminantsSheep, ruminants

Taenia pisiformisTaenia pisiformis Cysticercus pisiformisCysticercus pisiformis rabbitsrabbits

Taenia taeniaformisTaenia taeniaformis Cysticercus fasciolarisCysticercus fasciolaris rodentsrodents

Taenia multicepsTaenia multiceps Coenurus cerebralisCoenurus cerebralis Sheep And goatSheep And goat

Taenia saginataTaenia saginata Taenia soliumTaenia solium

Host is manHost is man manman

Rostellum is absent Rostellum is absent Present armed with hooksPresent armed with hooks

1000-2000 segments1000-2000 segments 800- 1000 segments800- 1000 segments

Ovary is bilobedOvary is bilobed trilobedtrilobed

Oval eggOval egg Spherical Spherical

Uterus has 14-32 branchesUterus has 14-32 branches 16 branches16 branches

Taenia soliumTaenia solium

Life cycle:Life cycle:

egg ( hatch after being ingested)egg ( hatch after being ingested)

Onchosphere ( migrates in different organs and tissues)Onchosphere ( migrates in different organs and tissues)

Cysticercus ( infective stage in the pork )Cysticercus ( infective stage in the pork )

Adult ( ingestion of infected ham and pork )Adult ( ingestion of infected ham and pork )

Man gets infection by the ff: waysMan gets infection by the ff: ways

1. ingestion of pork containing cysticercus1. ingestion of pork containing cysticercus

2. ingestion of eggs through the food and cysticercus develops in man2. ingestion of eggs through the food and cysticercus develops in man

3. by autoinfection due to retrosperistaltic movement. The eggs return to the stomach 3. by autoinfection due to retrosperistaltic movement. The eggs return to the stomach and hatchand hatch

Predisposing factors:Predisposing factors:

1. eating habits of people1. eating habits of people

2. large scale implementation of insewcticide 2. large scale implementation of insewcticide


ManMan

1. utilize the nutrition of the host 1. utilize the nutrition of the host

2. causes enteritis2. causes enteritis

3. neurocysticercosis3. neurocysticercosis

PigPig

1. measly pork- presence of cysticerci in different organs or tissue1. measly pork- presence of cysticerci in different organs or tissue

Clinical signs:Clinical signs:

Man NeurocysticercosisMan Neurocysticercosis

1. diarrhea 1. encephalitis and meningitis1. diarrhea 1. encephalitis and meningitis

2. abdominal pain 2. epileptic fit and excitement2. abdominal pain 2. epileptic fit and excitement

3. vomiting3. vomiting

4. flatulence4. flatulence

Taenia multicepsTaenia multiceps Life cycle:Life cycle:

eggeggOnchosphereOnchosphereCoenurus ( infective stage in the brain of sheep and goat )Coenurus ( infective stage in the brain of sheep and goat )AdultAdult

Pathogenesis:Pathogenesis:1.1. Migratory onchospheres care dangerous in the sheep. This causes Migratory onchospheres care dangerous in the sheep. This causes

meningitis and encephalitis meningitis and encephalitis

2.2. Gradually the cyst creates pressure in the brain as per the Gradually the cyst creates pressure in the brain as per the advancement of development of cyst. The brain muscles get advancement of development of cyst. The brain muscles get atrophiedatrophied

3.3. The skull gets atrophied and ultimately maybe soft and easily felt The skull gets atrophied and ultimately maybe soft and easily felt when touchingwhen touching

4.4. Aside from brain several nerves are also affected ( ocular, Aside from brain several nerves are also affected ( ocular, auditory )auditory )

Clinical signs:Clinical signs: 1. the animal looses the condition and fails to respond to the 1. the animal looses the condition and fails to respond to the

environmentenvironment 2. circling movement ( gid ) is an important sign2. circling movement ( gid ) is an important sign 3. sometimes the animals move in straight and keep its head on the 3. sometimes the animals move in straight and keep its head on the

hard surfacehard surface

Genus EchinicoccusGenus Echinicoccus E. granulosus E. granulosus

E. E. vogeli vogeli E. multilocularisE. multilocularis E. oligarthusE. oligarthus

Morphology:Morphology: 1. very small only few segments are present1. very small only few segments are present 2. terminal segment is the gravid segment2. terminal segment is the gravid segment 3. scolex has the rostellum which is armed with hooks3. scolex has the rostellum which is armed with hooks 4. ovary is kidney shaped4. ovary is kidney shaped

Life cycle:Life cycle: eggegg onchosphere onchosphere hydatid cyst in IHhydatid cyst in IH adultadult

Pathogenesis:Pathogenesis: 1. enteritis1. enteritis 2. pressure atrophy in the vital organs due to pressure of large- 2. pressure atrophy in the vital organs due to pressure of large-

sized cystsized cyst 3. functional disturbance3. functional disturbanceDiagnosis:Diagnosis: 1. examination of feces1. examination of feces 2. detection of cysticercus in the tongue and other palpable areas2. detection of cysticercus in the tongue and other palpable areas 3. Casonis Test- hydatid fluid is inoculated in the suspected 3. Casonis Test- hydatid fluid is inoculated in the suspected

individual and there would be hypersensitive reaction within 15 mins individual and there would be hypersensitive reaction within 15 mins or less in positive casesor less in positive cases

Family Mesocestoididae:Family Mesocestoididae:

Genus Mesocestoides Genus Mesocestoides M. lineatus M. jonesiM. lineatus M. jonesi

M. variabilisM. variabilis

M. tenuisM. tenuis


1. head or scolex is devoid of rostellum and hooks1. head or scolex is devoid of rostellum and hooks

2. presence of single set of reproductive system2. presence of single set of reproductive system

3. genital pore is dorsally situated3. genital pore is dorsally situated

4. bilobed ovary and vitelline glands4. bilobed ovary and vitelline glands

5. testes are situated on either side of the excretory canal5. testes are situated on either side of the excretory canal

DH- dog, fox, catDH- dog, fox, cat

IH- 1IH- 1stst – mites – mites

22ndnd - birds - birds

Developmental stages:Developmental stages:

eggegg


cysticercoid in IHcysticercoid in IH

tetrathyridium in birds, lizards, snakestetrathyridium in birds, lizards, snakes

adultadult

*M. corti can asexually multiply in the IH and DH*M. corti can asexually multiply in the IH and DH


1. enteritis1. enteritis

2. nervous disorder2. nervous disorder

3. anal priritus3. anal priritus

Genus DiphyllobothriumGenus Diphyllobothrium

Species:Species:

D. latumD. latum

D. mansonoidesD. mansonoides


1. long and maybe reaching up to several meters1. long and maybe reaching up to several meters

2. thousands of segments are presents2. thousands of segments are presents

3. head is spatula shaped with a deep groove in the middle called 3. head is spatula shaped with a deep groove in the middle called bothriabothria

4. no rostellum4. no rostellum

5. genital organs are situated mid-ventrally 5. genital organs are situated mid-ventrally

6. eggs are oval and operculated and have fair resemblance to 6. eggs are oval and operculated and have fair resemblance to trematodestrematodes

7. ovary is bilobed and uterus is rosette-shaped7. ovary is bilobed and uterus is rosette-shaped

Life cycle:Life cycle:

EggEgg

Ciliated coracidiumCiliated coracidium

Procercoid (cyclops)Procercoid (cyclops)

Plerocercoid (fish)Plerocercoid (fish)

AdultAdult

PathogenesisPathogenesis

1. enteritis 1. enteritis

2. anemia ( B12 def. or Pernicious anemia )2. anemia ( B12 def. or Pernicious anemia )

3. anal pruritus3. anal pruritus

4. epileptic fit4. epileptic fit

veterinary helminthology

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