CESTODES

CESTODESCESTODES

General CharacteristicsGeneral Characteristics

Majority are long, segmented and tape-like are called Majority are long, segmented and tape-like are called tapewormstapewormsDorso-ventrally flattened Dorso-ventrally flattened Size varies from a few mm to several metersSize varies from a few mm to several metersAdult worms are found in the intestinal canal of man and Adult worms are found in the intestinal canal of man and animalsanimals““head” or scolex is provided with suckers and sometimes head” or scolex is provided with suckers and sometimes with hooks that serve as organs of attachmentwith hooks that serve as organs of attachmentThere are 3 regions in an adult worm:There are 3 regions in an adult worm:

Head: scolexHead: scolexNeckNeckStrobila (body or trunk)Strobila (body or trunk)

Consist of a series of segment called proglottidsConsist of a series of segment called proglottids

General CharacteristicsGeneral Characteristics

Sexes are not separateSexes are not separateBody cavity is absentBody cavity is absentAlimentary canal is entirely absentAlimentary canal is entirely absentExcretory and nervous systems are presentExcretory and nervous systems are presentReproductive system is present and complete in each Reproductive system is present and complete in each segmentsegment

According to maturity of reproductive organs, three types of According to maturity of reproductive organs, three types of segments of the strobila can be recognized from the fron backwardssegments of the strobila can be recognized from the fron backwards

Immature: male and female organs are not differentiatedImmature: male and female organs are not differentiatedMature: male and female organs have become differentiated Mature: male and female organs have become differentiated (male organs appear first)(male organs appear first)Gravid: uteri are filled with eggs (other organs are atrophied or Gravid: uteri are filled with eggs (other organs are atrophied or have disappeared)have disappeared)

Classification of Cestodes Classification of Cestodes Infecting ManInfecting Man

I. Pseudophyllidean cestodesI. Pseudophyllidean cestodesPossess false or slit-like grooves called bothriaPossess false or slit-like grooves called bothria

Adult worms in IntestineAdult worms in IntestineDiphyllobothrium latum: Fish TapewormDiphyllobothrium latum: Fish Tapeworm

Larval stages: Plerocercoid in ManLarval stages: Plerocercoid in ManSparganum mansoniSparganum mansoni

Sparganum proliferumSparganum proliferum


II. Cyclophyllidean cestodesII. Cyclophyllidean cestodesPossess cup-like and round suckers called Possess cup-like and round suckers called acetabulaacetabula

Adult Worms in the IntestineAdult Worms in the IntestineTaenia saginataTaenia saginata

Taenia soliumTaenia solium

Hymenolepis nanaHymenolepis nana

Hymenolepis diminutaHymenolepis diminuta

Dipylidium caninumDipylidium caninum


According to HabitatAccording to Habitat

II. Cyclophyllidean cestodesII. Cyclophyllidean cestodesPossess cup-like and round suckers called Possess cup-like and round suckers called acetabulaacetabula

Larval Stages in ManLarval Stages in ManHydatid cyst of Hydatid cyst of Echinococcus granulosusEchinococcus granulosus and and Echinococcus multilocularisEchinococcus multilocularis

Cysticercus cellulosaCysticercus cellulosa of of Taenia soliumTaenia solium

Coenurus cerebralisCoenurus cerebralis of of Multiceps multicepsMulticeps multiceps

Coenurus glomeratusCoenurus glomeratus of of Multiceps glomeratusMulticeps glomeratus

Differences Between a Pseudophyllidean Differences Between a Pseudophyllidean and a Cyclophyllidean Cestodeand a Cyclophyllidean Cestode

PseudophyllideanPseudophyllidean CyclophyllideanCyclophyllidean

Head or scolexHead or scolex Bears 2 slit-like Bears 2 slit-like groovesgrooves

Bears 4cup-like Bears 4cup-like suckerssuckers

uterusuterus No branchingNo branching

Convoluted uterine Convoluted uterine tubes assume the tubes assume the form of rosettesform of rosettes

BranchingBranching

May or may not be May or may not be presentpresent

Uterine poreUterine pore presentpresent absentabsent

Common genital poreCommon genital pore Ventral; in the midlineVentral; in the midline laterallateral

eggseggs Operculated; gives Operculated; gives rise to ciliated larvaerise to ciliated larvae

Not operculated; do Not operculated; do not give rise to ciliated not give rise to ciliated larvaelarvae

Order PseudophyllideaOrder PseudophyllideaCharacteristicsCharacteristics

Large worms consisting of a long chain of segmentsLarge worms consisting of a long chain of segments““head” has two slit-like sucking grooves called bothria head” has two slit-like sucking grooves called bothria instead of suckersinstead of suckersUterine glands are widely scattered in the parenchyma and Uterine glands are widely scattered in the parenchyma and is composed of many aciniis composed of many aciniGenital pores are on the ventral surface of the segment and Genital pores are on the ventral surface of the segment and are not marginalare not marginalUterus opens to the exterior through which eggs come outUterus opens to the exterior through which eggs come outEggs are operculated and can develop only in water; Eggs are operculated and can develop only in water; immature when oviposited and oncosphere gives rise to immature when oviposited and oncosphere gives rise to ciliated embryociliated embryoLarval development proceeds in two intermediate hosts:Larval development proceeds in two intermediate hosts:

First larval stage is called procercoidFirst larval stage is called procercoidSecond larval stage is called plerocercoidSecond larval stage is called plerocercoid

Diphyllobothrium latumDiphyllobothrium latum

Common Name: Common Name: Fish TapewormFish TapewormBroad TapewormBroad Tapeworm

MorphologyMorphologyAdult worm is yellowish Adult worm is yellowish grey in colorgrey in colorDark central markings Dark central markings in the strobila are due in the strobila are due to the egg-filled uterusto the egg-filled uterusMeasures 3 to 10 Measures 3 to 10 meters in length meters in length Life-span is for a period Life-span is for a period of 5 to 15 yearsof 5 to 15 years

http://www.revistaaquatic.com/aquatic/html/art1401/fig11.gif 3-01-08


Scolex is spoon-shaped Scolex is spoon-shaped or spatulateor spatulate

Scolex bears 2 slit-like Scolex bears 2 slit-like grooves called bothria grooves called bothria (1 on the dorsal surface (1 on the dorsal surface and 1 on the ventral and 1 on the ventral surface)surface)

Scolex has no rostellum Scolex has no rostellum and no hookletsand no hooklets

Neck is thin and Neck is thin and unsegmented and is unsegmented and is much longer than the much longer than the headhead


MorphologyMorphology3,000 to 4,000 3,000 to 4,000 A mature segment is filled A mature segment is filled with male and female with male and female reproductive organsreproductive organsTerminal segments shrink Terminal segments shrink and becomes empty as and becomes empty as eggs are constantly eggs are constantly dischargeddischargedDried up segments break Dried up segments break off from the body in chains off from the body in chains and are passed out in the and are passed out in the host’s feceshost’s fecesUterus at the center of the Uterus at the center of the segment appears in the segment appears in the form of a rosetteform of a rosette


http://pathmicro.med.sc.edu/parasitology/dip1.jpg 3-01-08


OvaOvaPassed out in the host’s Passed out in the host’s feces in large numbersfeces in large numbersOvalOvalBile stainedBile stainedContains abundant Contains abundant granules and granules and unsegmented ovumunsegmented ovumInconspicuous operculum Inconspicuous operculum at one end and a small at one end and a small knob at the other endknob at the other endDoes not float in saturated Does not float in saturated solutions of common saltsolutions of common saltA single egg gives rise to A single egg gives rise to a single larvaa single larvaNot infective to manNot infective to man

http://workforce.cup.edu/Buckelew/images/Diphyllobothrium%20latum%20egg.jpg 3-01-08


larvalarvaPassed first in water and then in the respective intermediate Passed first in water and then in the respective intermediate hostshosts3 stage3 stage

– First stage larvaFirst stage larvaCoracidiumCoracidiumCiliated oncosphere that develops from egg in waterCiliated oncosphere that develops from egg in water

– Second stage larvaSecond stage larvaProcercoidProcercoidSpindle-like solid body with cephalic invaginationSpindle-like solid body with cephalic invaginationFound inside the cyclops (the first intermediate host)Found inside the cyclops (the first intermediate host)

– Third stage larva Third stage larva PlerocercoidPlerocercoidHead is invaginated in the neckHead is invaginated in the neckFound in the fresh water fish, the second intermediate hostFound in the fresh water fish, the second intermediate host



Diphyllobothrium latumDiphyllobothrium latumFinal HostFinal Host

Man, dog, catMan, dog, catSmall intestineSmall intestine

11stst I.H. I.H.Cyclops or DiaptomusCyclops or Diaptomus

22ndnd I.H. I.H.Fresh water fish, pike, trout, salmon, perchFresh water fish, pike, trout, salmon, perch

Mode of InfectionMode of InfectionIngestion of imperfectly cooked infected fish or roe containing Ingestion of imperfectly cooked infected fish or roe containing plerocercoid larvaeplerocercoid larvae

InfectionInfectionDiphyllobothriasisDiphyllobothriasisG.I. disturbances and anemiaG.I. disturbances and anemia

DiagnosisDiagnosisMicroscopic examination of feces for the characteristic Microscopic examination of feces for the characteristic operculated eggsoperculated eggs

Order CyclophyllideaOrder CyclophyllideaCharacteristicsCharacteristics

Large or small worms consisting of chains of segmentsLarge or small worms consisting of chains of segmentsScolex is quadrate with four cup-like round suckers Scolex is quadrate with four cup-like round suckers An apical rostellum with hooklets may be presentAn apical rostellum with hooklets may be presentVitelline glands concentrated in a single mass Vitelline glands concentrated in a single mass Common genital pore is marginal (on lateral side of Common genital pore is marginal (on lateral side of segment)segment)No uterine opening for the exit of eggs from the gravid No uterine opening for the exit of eggs from the gravid uterusuterusEggs only escape from the rupture or disintegration of ripe Eggs only escape from the rupture or disintegration of ripe segmentssegmentsEggs are not operculated and can develop only in the Eggs are not operculated and can develop only in the intermediate host, fully embryonatedintermediate host, fully embryonatedOncosphere is never a ciliated embryoOncosphere is never a ciliated embryoLarval development proceeds in one intermediate hostLarval development proceeds in one intermediate host

Taenia saginataTaenia saginata

Beef TapewormBeef TapewormUnarmed Tapeworm Unarmed Tapeworm of Manof ManAdult worms are white Adult worms are white and semi-transparentand semi-transparentMeasures about 5-10 Measures about 5-10 meters or sometimes meters or sometimes up to 24 metersup to 24 metersLive up to 10 years or Live up to 10 years or moremore

Taenia saginataTaenia saginata1,000 to 2,000 proglottids1,000 to 2,000 proglottidsCommon genital pore is marginally Common genital pore is marginally situatedsituatedVagina is provided with a Vagina is provided with a sphincter musclesphincter muscleGravid proglottid consists of a Gravid proglottid consists of a uterus and a central longitudinal uterus and a central longitudinal stem with 15 – 30 branches on stem with 15 – 30 branches on each sideeach sideHighly branched proglottidsHighly branched proglottidsGravid proglottid contains 97,000 Gravid proglottid contains 97,000 to 124,000 ovato 124,000 ovaGravid segments are expelled Gravid segments are expelled singly and force their way through singly and force their way through the anal sphincterthe anal sphincterFree gravid proglottid crawls out of Free gravid proglottid crawls out of the anal orifice and oviposits on the anal orifice and oviposits on the perianal skinthe perianal skin



OvaOvaLiberated by rupture of Liberated by rupture of ripe proglottidsripe proglottidsNo uterine openingNo uterine openingSphericalSphericalThin, outer transparent Thin, outer transparent shellshellInner embryophore is Inner embryophore is brown, thick walled and brown, thick walled and radially striatedradially striatedHas an oncosphere with 3 Has an oncosphere with 3 pairs of hookletspairs of hookletsDoes not float in saturated Does not float in saturated salt solutionssalt solutionsEggs are resistant and Eggs are resistant and remain viable for 8 weeksremain viable for 8 weeksInfective only to cattleInfective only to cattle


Final Host: ManFinal Host: ManIntermediate Host: cattle, cow buffaloIntermediate Host: cattle, cow buffaloMode of Infection; eating beef containing Mode of Infection; eating beef containing Cysticercus Cysticercus bovisbovisPathogenesisPathogenesis

TaeniasisTaeniasisPassage of proglottids in stoolPassage of proglottids in stoolMild irritation at site of attachmentMild irritation at site of attachmentEpigastric painEpigastric painHunger fangsHunger fangsWeaknessWeaknessWeight lossWeight lossLoss of appetiteLoss of appetitePruritisPruritisObstruction in intestine but also in bile and pancreatic ducts and Obstruction in intestine but also in bile and pancreatic ducts and appendix because proglottids are actively motileappendix because proglottids are actively motile


DiagnosisDiagnosisIdentifying characteristic eggs, proglottids or scolexIdentifying characteristic eggs, proglottids or scolexUsual specimen is gravid proglottids ( lateral Usual specimen is gravid proglottids ( lateral branches 15-20)branches 15-20)Concentration techniques for eggs (eggs rarely Concentration techniques for eggs (eggs rarely passed out in stool)passed out in stool)Perianal swabsPerianal swabs

TreatmentTreatmentPraziquantelPraziquantel5-10mg/kg single dose5-10mg/kg single dose

Criteria for cureCriteria for cureRecovery of the scolexRecovery of the scolexNegative stool examination 3 months after treatmentNegative stool examination 3 months after treatment


Pork Tape wormPork Tape wormArmed Tapeworm of ManArmed Tapeworm of ManTaeniasis is common among Taeniasis is common among those eating raw or insufficiently those eating raw or insufficiently cooked “measly pork”cooked “measly pork”Uncommon among non-pork Uncommon among non-pork eaterseaters


Scolex is globular in Scolex is globular in outline with 4 circular outline with 4 circular suckerssuckersScolex has a Scolex has a rostellum armed with rostellum armed with a double row of a double row of alternating large and alternating large and small hookletssmall hookletsRostellar hooklets are Rostellar hooklets are shaped like daggers shaped like daggers or Arabian poniardsor Arabian poniards




Adult worms measure Adult worms measure 2-3 meters 2-3 meters Adult worms live up to 25 Adult worms live up to 25 yearsyears


800-900 proglottids800-900 proglottidsCommon genital pore is Common genital pore is marginal and thick lippedmarginal and thick lippedVaginal opening is not Vaginal opening is not guarded by a muscular guarded by a muscular sphinctersphincterGravid segments are Gravid segments are expelled passively in expelled passively in chains of 5-6 at a time chains of 5-6 at a time and not singly.and not singly.Gravid proglottids Gravid proglottids contains approx. 30,000 contains approx. 30,000 to 50,000 eggsto 50,000 eggs


Ova Ova – Same as those of Same as those of

Taenia saginataTaenia saginata– Infective to man as Infective to man as

well as pigswell as pigs– Thick brown striated Thick brown striated

embryophore embryophore surrounding a surrounding a hexacanth embryohexacanth embryo


Final Host: ManFinal Host: Man

Intermediate Host: PigIntermediate Host: Pig

Mode of infection; eating measly pork Mode of infection; eating measly pork containing containing Cysticercus cellulosaeCysticercus cellulosae

Diagnosis: stool examination for Diagnosis: stool examination for proglottids/eggsproglottids/eggs


PathogenesisPathogenesisMild, non-specific abdominal complaintsMild, non-specific abdominal complaints

Proglottids are not as motile as Proglottids are not as motile as T. saginataT. saginata so organ so organ obstruction is less likely.obstruction is less likely.

CysticercosisCysticercosisMultipleMultiple

Develop in any organ or tissueDevelop in any organ or tissue

Neurocysticercosis (most serious zoonotic disease)Neurocysticercosis (most serious zoonotic disease)

ChorioretinitisChorioretinitis

vasculitisvasculitis


DiagnosisDiagnosisIntestinalIntestinal

Identifying the characteristic proglottids, eggs or scolexIdentifying the characteristic proglottids, eggs or scolex

CysticercosisCysticercosisComputed Axial TomographyComputed Axial TomographyMagnetic Resonance ImagingMagnetic Resonance Imaging

TreatmentTreatmentPraziquantel: 5-10 mg/kg single dose for children and adultsPraziquantel: 5-10 mg/kg single dose for children and adultsNiclosamide not available locallyNiclosamide not available locally

Criteria for cure:Criteria for cure:Recovery of scolexRecovery of scolexNegative stool exam 3 months after treatment Negative stool exam 3 months after treatment

Comparison Between Comparison Between T. saginataT. saginata and and T. soliumT. solium

Taenia saginataTaenia saginata Taenia soliumTaenia soliumlengthlength 5-10 meters5-10 meters 2-5 meters2-5 meters

Head or scolexHead or scolex Large, quadrate, no Large, quadrate, no rostellum and hooksrostellum and hooks

Armed; with rostellum; Armed; with rostellum; with hookletswith hooklets

Number of proglottidsNumber of proglottids 1,000 to 2,0001,000 to 2,000 Below 1000Below 1000

ExpulsionExpulsion Expelled singly and may Expelled singly and may be forced through the be forced through the anal sphincteranal sphincter

Explelled passively in Explelled passively in chains of 5 or 6chains of 5 or 6

uterusuterus Highly branched with 15-Highly branched with 15-30 lateral branches on 30 lateral branches on each side; thin; each side; thin; dichotomousdichotomous

Lateral branches 5-10 on Lateral branches 5-10 on each side, thin, dendritic each side, thin, dendritic and vaginal sphincter is and vaginal sphincter is absentabsent

testestestes 300-400 follicles300-400 follicles 150-200 follicles150-200 follicles

Echinococcus granulosusEchinococcus granulosus

Taenia echinococcusTaenia echinococcus

Dog TapewormDog Tapeworm

Hydatid WormHydatid Worm

Man harbors the larval form and not the Man harbors the larval form and not the adult worms which however is found in the adult worms which however is found in the intestine of dogs and caninesintestine of dogs and canines


Adult worms are small Adult worms are small (3-6 mm in length)(3-6 mm in length)It is composed of a It is composed of a

ScolexScolexNeckNeckStrobilaStrobila

3 segments 3 segments (occassionally 4)(occassionally 4)

ImmatureImmatureMatureMatureGravidGravid


Scolex bears 4 Scolex bears 4 suckers and a suckers and a protrusible rostellum protrusible rostellum with 2 circular rows of with 2 circular rows of hooks.hooks.


OvaOvaOvoid in shapeOvoid in shape

Resemble Taenia ovaResemble Taenia ova

Hexacanth embryo with Hexacanth embryo with 3 pairs of hooks3 pairs of hooks

Infective to:Infective to:ManMan

CattleCattle

Sheep and other Sheep and other herbivorous animalsherbivorous animals


LarvaLarvaFound within the hydatid cyst developing inside the Found within the hydatid cyst developing inside the intermediate hostintermediate hostRepresents the structure of the scolex of the future Represents the structure of the scolex of the future adult wormadult wormYoung larva are transformed into a hollow bladder Young larva are transformed into a hollow bladder (hydatis , drop of water)(hydatis , drop of water)Brood capsules develop within the cysts and may Brood capsules develop within the cysts and may contain thousands of scolicescontain thousands of scolicesOn entering the final host, the scolex armed with a On entering the final host, the scolex armed with a rostellum and 4 suckers become adult wormsrostellum and 4 suckers become adult worms




Definitive HostDefinitive HostDogDog

WolfWolf

Fox Fox

JackalJackal

Intermediate HostIntermediate HostSheepSheep

PigPig

CattleCattle

HorseHorse

GoatGoat


Definitive HostDefinitive HostDogDog

WolfWolf

Fox Fox

JackalJackal

Intermediate HostIntermediate HostSheepSheep

PigPig

CattleCattle

HorseHorse

GoatGoat


PathogenesisPathogenesisEchinococcosisEchinococcosis

Pathology is caused by the developing larval cyst Pathology is caused by the developing larval cyst in the intermediate hostin the intermediate hostMost common site of involvement is the liverMost common site of involvement is the liverEchinococcus granulosusEchinococcus granulosus cyst: Unilocular hydatid cyst: Unilocular hydatid cystcystEchinococcus multilocularisEchinococcus multilocularis: alveolar cyst: alveolar cystSome may be asymptomatic for yearsSome may be asymptomatic for yearsRupture of cyst in the lungs may present coughing Rupture of cyst in the lungs may present coughing accompanied by allergic reactionsaccompanied by allergic reactions



Encysted scolices of Echinococcus granulosus in lung "hydatid sand"






DiagnosisDiagnosisRadiographic findingsRadiographic findings

ImmunodiagnosisImmunodiagnosis

Antibody detectionAntibody detectionIHAIHA

IFAIFA

EIAEIA

Antigen detectionAntigen detection


TreatmentTreatmentSurgical resection: not 100% effectiveSurgical resection: not 100% effective

Solicidal agentSolicidal agentHibitaneHibitane

95% ethanol95% ethanol

Hypertonic 30% Normal Saline SolutionHypertonic 30% Normal Saline Solution

PAIR technique for inoperable cystPAIR technique for inoperable cystPuncture, Aspiration, Injection, Reaspiration Puncture, Aspiration, Injection, Reaspiration InterventionIntervention

AlbendazoleAlbendazole

Hymenolepis speciesHymenolepis species

Genus is derived from the membranous character of the Genus is derived from the membranous character of the egg shell “hymen”egg shell “hymen”3 testes in each mature segment3 testes in each mature segmentUterus is sac-like and transverseUterus is sac-like and transverseEggs possess two membranes’ outer membrane is thin Eggs possess two membranes’ outer membrane is thin and transparentand transparentlarval stage is called cysticercoidlarval stage is called cysticercoidSmall bladder containing the invaginated head proximally Small bladder containing the invaginated head proximally and a solid, elongted portion as a caudal appendageand a solid, elongted portion as a caudal appendageThere are 2 species;There are 2 species;

Hymenolepis nanaHymenolepis nanaHymenolepis diminutaHymenolepis diminuta


Dwarf TapewormDwarf TapewormSmallest tapeworm infecting manSmallest tapeworm infecting manFound worldwideFound worldwideMainly among childrenMainly among childrenOnly human tapeworm that can complete its life Only human tapeworm that can complete its life cycle in a single hostcycle in a single hostMan can harbor both the adult and larval stages Man can harbor both the adult and larval stages of the parasiteof the parasiteException to the general rule that Exception to the general rule that

““Helminths do not multiply inside the body Helminths do not multiply inside the body of the definitive host”of the definitive host”


AdultAdultFound in the ileumFound in the ileumDelicate strobilaDelicate strobila25 mm to 45 mm25 mm to 45 mmWorms may be presenr in Worms may be presenr in large numbers from 1,000 large numbers from 1,000 to 8,000to 8,000Short life span, about 2 Short life span, about 2 weeksweeksUp to 200 proglottidsUp to 200 proglottidsTransverse uterusTransverse uterus3 testes3 testes


ScolexScolexSubglobularSubglobular4 suckers4 suckersProvided with a Provided with a short retractile short retractile rostellum armed rostellum armed with a single row of with a single row of 20-30 hooklets20-30 hookletsRostellar hooklets Rostellar hooklets are shaped like are shaped like tuning forkstuning forks


OvaOvaSpherical or ovalSpherical or oval

Floats in saturated Floats in saturated solutions of common solutions of common saltsalt

2 distinct membranes2 distinct membranesOuter membrane is Outer membrane is thin transparent and thin transparent and colorlesscolorlessInner embryophore Inner embryophore that encloses an that encloses an oncosphere with 3 oncosphere with 3 pairs of lancet shaped pairs of lancet shaped hookletshookletsIntermembranous Intermembranous space is filled with space is filled with yolk granules and 4-8 yolk granules and 4-8 polar filaments polar filaments emating from little emating from little knobs at either end of knobs at either end of the embryophorethe embryophore



Mode of transmission is thru Mode of transmission is thru

Direct Direct Host ingests eggs that hatches in the duodenumHost ingests eggs that hatches in the duodenum

Indirect pathwayIndirect pathwayAccidental ingestion of infected arthropod Accidental ingestion of infected arthropod intermediate host like rice and flour beetles in intermediate host like rice and flour beetles in which cysticercoid arve are released nd develop which cysticercoid arve are released nd develop into adult worms in the small intestine of the hostinto adult worms in the small intestine of the host


PathogenesisPathogenesisSymptoms are produced due to patient’s immunological Symptoms are produced due to patient’s immunological response to the parasiteresponse to the parasiteAsymptomatic for light worm burdenAsymptomatic for light worm burdenHeadacheHeadacheDizzinessDizzinessAnorexiaAnorexiaPruritus of the nose and anusPruritus of the nose and anusAbdominal painAbdominal painPallorPallorDesquamation of intestinal epithelial cell or as serious as Desquamation of intestinal epithelial cell or as serious as necrosis may occurnecrosis may occur

Regulatory immunity will eventually limit the Regulatory immunity will eventually limit the infectioninfection


Diagnosis Diagnosis Demonstration of characteristic ova in the stoolDemonstration of characteristic ova in the stoolProglottids are not recovered because they Proglottids are not recovered because they undergo degeneration prior to passageundergo degeneration prior to passage

TreatmentTreatmentPraziquantelPraziquantel– 25mg/kg single dose25mg/kg single dose– Drug dosage is higher than that of taeniasis Drug dosage is higher than that of taeniasis

because of resistant cysticercoids in intestinal because of resistant cysticercoids in intestinal tissuetissue


EpidemiologyEpidemiologyCountries with warm temperatureCountries with warm temperature

Southern USASouthern USA

Latin AmericaLatin America

MediterraneanMediterranean

East AsiaEast Asia

PhilippinesPhilippines


Rat tapewormRat tapeworm

Common parasite of rats and miceCommon parasite of rats and mice

Accidental human infectionsAccidental human infections

Differs from Differs from Hymenolepis nana Hymenolepis nana in morphology in morphology and life cycle because it requires an and life cycle because it requires an intermediate hostintermediate host

2 Hosts2 HostsLarval stage: cysticercoid is passed in fleasLarval stage: cysticercoid is passed in fleas

Adult stage: in rats and mice and accidentally in humans Adult stage: in rats and mice and accidentally in humans especially children who accidentally ingest infected fleasespecially children who accidentally ingest infected fleas


AdultAdultLarger than Larger than Hymenolepis nanaHymenolepis nana

Measures 60 cm in Measures 60 cm in lengthlength


ScolexScolex

Unarmed Unarmed rostellumrostellum

4 suckers4 suckers



ProglottidProglottid8,00 – 1,0008,00 – 1,000Mature proglottids of Mature proglottids of Hymenolepis diminutaHymenolepis diminuta from the laboratory rat. from the laboratory rat.

The three spherical The three spherical bodies are testes which bodies are testes which surround the ovaries, surround the ovaries, ootype and vitelline ootype and vitelline glands. The genital glands. The genital pores are on the left pores are on the left margin margin


OvaOvaLarger than Larger than H. H. nanananaOuter shell is Outer shell is yellowish in coloryellowish in colorInner Inner embryohore has embryohore has 2 knob-like 2 knob-like thickeningsthickeningsNo polar No polar filamentsfilaments


cysticercoid ofcysticercoid of Hymenolepis Hymenolepis diminutadiminuta. . The suffix indicates it is like a The suffix indicates it is like a cysticercus but this larva has cysticercus but this larva has no bladder but instead has a no bladder but instead has a tail. tail. The dark body within the The dark body within the spherical portion is the scolex. spherical portion is the scolex. The longer the tail, the more The longer the tail, the more mature the cysticercoid. mature the cysticercoid. This stage is found inside an This stage is found inside an insect such as the mealworm, insect such as the mealworm,



PathogenesisPathogenesis

HymenolepiasisHymenolepiasis

Worm burden in rodents is relatively Worm burden in rodents is relatively lowlow

In man, highest worm burden is 19In man, highest worm burden is 19

Clinical manifestations are minimal Clinical manifestations are minimal and non-specificand non-specific


TreatmentTreatmentPraziquantelPraziquantel25mg/kg body weight single dose25mg/kg body weight single doseEpidemiologyEpidemiologyWorld wideWorld wideCommon among children due to ingestion of Common among children due to ingestion of infected grain beetles, dried fruits, flour and infected grain beetles, dried fruits, flour and cerealscerealsPrevalence of Prevalence of H. diminutaH. diminuta in Philippine rats is in Philippine rats is about 8%about 8%


Double Pored Dog TapewormDouble Pored Dog Tapeworm

Presence of bilateral genital pores in each Presence of bilateral genital pores in each segment (di: 2; pylis: gate): 2 entrancessegment (di: 2; pylis: gate): 2 entrances

Common intestinal parasite of dogsCommon intestinal parasite of dogs


AdultAdult10-70 cm in 10-70 cm in lengthlength

Pale reddishPale reddish


ScolexScolexSmall and Small and globularglobular4 deeply cupped 4 deeply cupped elliptical suckerselliptical suckersProtrusible/Protrusible/retractile retractile rostellumrostellumRostellum has 1-Rostellum has 1-7 rows of rose 7 rows of rose thorn shaped thorn shaped hookletshooklets



StrobilaStrobila200 200 proglottidsproglottids

narrownarrow


Mature Mature proglottidsproglottids

2 sets of male 2 sets of male and female and female reproductive reproductive organsorgans

Bilatera genital Bilatera genital porespores


Gravid Gravid proglottidsproglottids

Have size and Have size and shape of shape of pumpkin seedspumpkin seedsFilled with Filled with capsules or capsules or packets of 8-15 packets of 8-15 eggs enclosed n eggs enclosed n an embryonic an embryonic membranemembrane


Proglottids



OvaOvaPassed out in the feces Passed out in the feces along with the along with the proglottidsproglottids

Released by Released by contraction of contraction of proglottids or proglottids or disintegration outside disintegration outside the hostthe host

SphericalSpherical

Thin shelledThin shelled

With a hexacanth With a hexacanth embryoembryo


Intermediate hostsIntermediate hosts

Ctenocephalides canis : Ctenocephalides canis : dog fleadog flea

Ctenocephalides felis :Ctenocephalides felis : cat flea cat flea

Pulex irritansPulex irritans : human flea : human flea

Trichoedectes canisTrichoedectes canis : dog flea : dog flea


PathogenesisPathogenesisDipylidiasisDipylidiasis

Rarely multipleRarely multiple

Symptoms are minimalSymptoms are minimalSlight intestinal discomfortSlight intestinal discomfort

Epigastric painEpigastric pain

DiarrheaDiarrhea

Anal pruritusAnal pruritus

Allergic reactionsAllergic reactions


TreatmentTreatmentPraziquantelPraziquantel5-10 mg/kg body weight single dose5-10 mg/kg body weight single doseEpidemiologyEpidemiologyUSAUSARhodesiaRhodesiaArgentinaArgentinaChinaChinaPhilippinesPhilippines


CESTODES

Documents

cyclophyllidean

fresh water

man intermediate

adult worms

intermediate

larval stage

hymenolepis

ventral surface