Lec 12: Cestodes Part 2

Dipylidium caninum

Very common intestinal parasite of dogs and cats, especially dogs

* Ctenocephalides canis
* Ctenocephalides felis
* Pulex irritans
* Trichodectes canis

Dipylidium caninum: Intermediate host

Ctenocephalides canis

dog flea

Ctenocephalides felis

cat flea

Pulex irritans

Human flea

Trichodectes canis

dog louse

Dipylidium caninum

Dipylidiasis more common in children than adults

Dipylidium caninum, scolex

* Small and globular
* Has 4 deeply cupped suckers and protrusible rostellum armed with one to seven rows of thorn-shaped hooklets

Has 4 deeply cupped suckers and protrusible rostellum armed with one to seven rows of thorn-shaped hooklets

Describe Dipylidium caninum scolex

Dipylidium caninum: Proglottids

Adult worm measures 10 to 70 cm in length

Dipylidium caninum: Proglottids

Proglottids are narrow with two sets of female and male reproductive organs and bilateral genital pores → double-pored tapeworm

Dipylidium caninum: Proglottids

Gravid proglottids have 8 to 15 eggs enclosed in an embryonic membrane

Dipylidium caninum: Ova

Spherical, thin-shelled with hexacanth embryo

Infection is rarely heavy and symptoms are minimal or non-specific

Dipylidium caninum: Pathogenesis

* Identification of characteristic passed out gravid Proglottids
* Stool sample not recommended

Dipylidium caninum: Diagnosis

Praziquantel 5 to 10 mg/kg single dose

Dipylidium caninum: Treatment

Dipylidium caninum: Epidemiology

* Reported in European countries, USA, Argentina, Rhodesia, China and Philippines
* Periodic deworming of pet cats and dogs is highly recommended

hand to mouth contamination or accidentally swallowing the arthropod host

Dipylidium caninum: MOT

8-15 eggs

\[Dipylidium caninum, Egg packets\]

Each egg packet may contain _________ eggs

Davaineidai

Raillietina garrisoni is from the family _____________

Raillietina garrisoni

Common tapeworm in rats

Raillietina garrisoni: Intermediate host

Raillietina garrisoni

In ________________, almost all human infections in the Philippines involved children

Raillietina garrisoni, scolex

Minute, sub-globular scolex with four acetabula

Rostellum armed with two alternation circular rows of 90 to 140 hammer-shaped hooks with several rows of spines

Describe Raillietina garrisoni scolex

Raillietina garrisoni: Proglottids

Adult tapeworm about 60m in length

Raillietina garrisoni: Proglottids

Mature proglottid has bilobed ovary surroundedby 36-50 ovoid testes

Raillietina garrisoni: Proglottids

Genital pores open on the side near the anterior lateral border of the segment

Raillietina garrisoni: Proglottids

Fully gravid proglottids contains 200 to 400 egg capsules

Raillietina garrisoni: Proglottids

Appear like grains of rice when passed out with feces

Oncospheres have 2 thin membranes

Raillietina garrisoni: Ova

* Outer elongated membrane
* Inner spherical membrane

\[Raillietina garrisoni\]

Oncospheres have 2 thin membranes:

Asymptomatic

Raillietina garrisoni: Pathogenesis

Identification of characteristic proglottid or ova in stool

Raillietina garrisoni: Diagnosis

* Praziquantel
* Long strobila or complete tapeworm may beexpelled spontaneously

Raillietina garrisoni: Treatment

Raillietina garrisoni

Infections reported in Tokyo, Taiwan, Australia, Ecuador and North Iran

Diphyllobothrium latum

* Fish tapeworm or broad tapeworm
* causes Diphyllobothriasis in human

Diphyllobothrium latum, scolex

Spatulate; measures 2 to 3 mm in length by 1 mm

Diphyllobothrium latum, scolex

* Two bothria or sucking grooves located dorsally and ventrally
* Neck is long and attenuated

Two bothria or sucking grooves located dorsally and ventrally

Describe Diphyllobothrium latum scolex

Diphyllobothrium latum: Proglottids

Mature proglottid has longer width than its length, measures 2 to 4mm length by 10 to 12mm

Diphyllobothrium latum: Proglottids

Only one set of reproductive organs

* In the dorsolateral part
* Vas efferens converge to form vas deferens enlarging into a seminal vesicle
* Terminated in a muscular cirrus in the midventral common genital pore

Diphyllobothrium latum: Testes

* Dark, rosette-like, coiled in the middle of the gravid proglottid
* Approx 1 million unembryonated ova may be released per day

Diphyllobothrium latum: Uterus

Diphyllobothrium latum: Uterus

Approx 1 million unembryonated ova may be released per day

Bilobed; at the posterior third portion above the Mehli’s gland

Diphyllobothrium latum: Ovary

Diphyllobothrium latum: Vagina

From the common genital pore extends to join up to join the oviduct and vitelline duct

* Yellowish brown
* Moderately thick shell and inconspicuous operculum
* Opposite to operculum is a small knob-like thickening

Diphyllobothrium latum: Ova

Vitamin B12

\[Diphyllobothrium latum\]

Worms in the jejunum compete with _________________ in the diet

Cyclops & Diaptomus

Diphyllobothrium latum: Intermediate host

RBC production

\[Diphyllobothrium latum\]

Importance of Vitamin B12

Pernicious anemia

\[Diphyllobothrium latum\]

Characterized by Vitamin B12 deficiency

Examine the gastric juice

How do you differentiate anema caused by Diphyllobothrium latum?

Achlorhydia

absence of hydrochloric acid in the gastric secretions

* Identification of characteristic operculated eggs or proglottids in stool
* Examination of gastric juice for free hydrochloric acid

Diphyllobothrium latum: Diagnosis

Praziquantel 5 to 10 mg/kg single dose

Diphyllobothrium latum: Treatment

* Recovery of scolex in stool
* Repeat stool examination 3 months post treatment

Diphyllobothrium latum: Criteria for cure

Diphyllobothrium latum

Common in temperate zones where population has a habit of eating raw or improperly cooked fish

Diphyllobothrium latum

Present in Baltic countries, Switzerland, Romania, the Danube; Russia, Turkistan, Israel, Northern Manchuria, Japan; Chile, Argentina, North America, Canada

Thorough cooking of freshwater fish or freezing for 24 to 48 hours at -18°C

Diphyllobothrium latum: Prevention

Fish-eating mammals, Humans

Diphyllobothrium latum: Definitive hosts

1. Unembryonated eggs
2. Embryonate in water
3. Coracidium hatch from egg
4. Ingested by copepod (Cyclops & Diaptomus)
5. Procercoid larvae develops inside IH
6. Plerocercoid larva

Diphyllobothrium latum: Life cycle

Taeniidae

Echinococcus spp. Belong to the Family _________

Cyclophyllidean

Echinococcus spp. Belong to the Order _______________

* E. granulosus
* E. multilocularis
* E. vogeli
* E. oligarthus

Echinococcus spp. recognized species

Echinococcus granulosus

cystic echinococcosis

Echinococcus multilocularis

alveolar echinococcosis

Echinococcus vogeli and Echinococcus oligarthus

polycystic echinococcosis

Echinococcus granulosus, scolex

* Pyriform
* Four acetabula armed with 30-36 hooks

Four acetabula armed with 30-36 hooks

Describe Echinococcus granulosus scolex

Echinococcus granulosus: Proglottids

* Adult measures 3 to 6mm
* Uterus midline with lateral evaginations

Has oncospheres that migrate into the mesenteric venules

Echinococcus granulosus: Ova

Echinococcus granulosus: Hydatid cyst

* Larval stage
* Measures 1 to 7 cm in diameter
* Has outer laminated hyaline layer and inner nucleated germinal layer

Hydatid sand

* Brood capsule rupture and release protoscolices
* Collective term for protoscolices

Liver

\[Echinococcus granulosus\]

Most common and important site of involvement:

Liver

\[Echinococcus granulosus\]

70% of cases occurs in this organ

Lungs

\[Echinococcus granulosus\]

20-30% of cases occurs in this organ

Brain

\[Echinococcus granulosus\]

10% of cases occurs in this organ

right lobe

\[Echinococcus granulosus\]

In the liver, about 85% of cases occur in the _________

Echinococcus granulosus

Unilocular hydatid cyst seen in

asymptomatic

\[Echinococcus granulosus\]

Simple or uncomplicated cysts may be ______

serious anaphylactic reaction

Ruptured cysts causes

intermittent jaundice, fever, eosinophilia

\[Echinococcus: Serious anaphylactic reaction\]

Liver

Echinococcus granulosus

Dog tapeworm

Echinococcus granulosus

Hydatid tapeworm

sudden coughing, sputum may contain frothy blood, mucus, hydatid fluid and membrane

\[Echinococcus: Serious anaphylactic reaction\]

Lungs

increased ICP, Jacksonian epilepsy

\[Echinococcus: Serious anaphylactic reaction\]

Brain

hematuria, kidney dysfunction, hydatid material in urine

\[Echinococcus: Serious anaphylactic reaction\]

Kidneys

* Radiography + ultrasonography
* History of residence in endemic area
* Close association with dogs
* Serology: (80-100% sensitivity, 88-96% specificity)
* IHA
* IFA
* EIA

Echinococcus granulosus: Diagnosis

ELISA or Immunoblot: IgG antibodies to hydatid cyst

Echinococcus granulosus: Serologic gold standard

Large cysts (>10cm): Surgical resection

GOLD STANDARD

Echinococcus granulosus: Treatment for Large cysts

Small cysts (

Echinococcus granulosus: Treatment for Small cysts

Percutaneous aspiration, injection, re-aspiration (PAIR)

Echinococcus granulosus: Treatment if surgery is contraindicated

95% ethanol or hypertonic saline for 15 mins

proctoscolicidal agent

Echinococcus granulosus

Temperate zone countries: South America, Mediterranean, southern and central Russia, Central Asia, China, Australia, Africa, Bulgaria

* Regular testing and treatment of dogs with praziquantel in endemic areas
* Vaccination of livestock

Echinococcus granulosus: Prevention

Dogs

Echinococcus granulosus: Definitive host

Goats, Horses, Camels, Sheep, Humans (Incidental)

Echinococcus granulosus: Intermediate host

Cysticercus bovis

What is the infective stage of T. saginata to its host?

Cysticercus cellulosae

What is the infective stage of T.solium to its host?