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What broad parasitic category are the Cestodes in, along w/ what other 2 things?
-along with Platyhelminths and Flukes
What are the 5 Cestode genera that are most important?
1. Taenia
2. Hymenolepis nana
3. Echinococcus granulosus
4. Diplylidium caninum
5. Diphyllobothrium latum
What are three cestodes that are very rare?
1. Echinococcus multilocularis
2. Sparganosis
3. Multiceps species
What are the cestodes really?
In general, what type of cycle do the cestode adults/larvae switch off in?
Adults: live in vertebrate intestines.

Larvae live in vertebrate/inverbt tissues -this is the intermediate stage.
Regarding Cestode adults:
-outer covering
-feature of digestive tract
-sexual nature
-Integument covering
-No intestinal tract
What 3 parts do cestode adults have?
1. Scolex - w/ hooks/suckers
2. Neck
3. Strobila: proglottid chain
At which end of the cestode are the proglottids more mature?
Posterior; they are "born" at the head.
What sets apart mature proglottids?
they have an ova, uterus, and testes.
What is the general life cycle of cestodes?
1. Humans ingest the larval infectious stage in raw meat.
2. Larva -> sm intestine, scolex evaginates/attaches to mucosa
3. Adult develops, fertilizes, lays ova, shed in feces.
4. Ova ingested by intermediate host, embryonate in intestine, penetrate intestinal wall and enter intramuscular tissue.
5. Humans, being carnivores, eat the muscle and get infect.
How are all cestode infections treated?
What 2 species of Taenia do we know?
Taenia saginata
Taenia solium
What disease does Taenia saginata cause?
-What's its common name?
aka, Beef Tapeworm
What are the defin/intermed hosts of Taenia saginata?
Definitive: only HUMANS
Intermediate: Cattle, herbivores
What is the infectious stage of Taenia saginata?
Cysticercus larva
How long is the T. saginata adult?
How many uterine branches p. gravid proglottid?
4-6 meters!! VERY long

15-30 branches p. side of proglottid.
What does the adult scolex have?
Suckers, but no hooks
What are characteristics of the Taenia ovum?
-Radially striated embryophore
-Hexacanth Embryo
-6 hooks in fully mature ovum
What symptoms are seen in taeniasis?
Vague, abdom pain, diarrhea, weight loss.
Loss of bowel control
Rare appendicitis
How is Taeniasis diagnosed?
Ova in stool
Must see the proglottid to speciate!!!
How is Taeniasis prevented?
Cook beef well
Freeze beef might help
Inspect beef for larvae
Dispose human feces sanitarily
What is the common name of Taenia solium infection?
PORK tapeworm
what are the definitive and intermediate hosts of Taenia solium?
Defin: humans
Intermed: pigs, may be huamans
what is the taenia solium larvae that lodges in the intermed. host? What do they cause?
Cysticercus larvae, they cause Cysticercus cellulosae
How long is the adult taenia solium?
2-4 meters - shorter than T. saginata which is 4-6 meters.
How many uterine branches are there per gravid proglottid of T. solium? What's special 'bout the scolex?
Scolex has Rostellum = ledge for hooks to set on
What is the course of disease in humans caused by T. solium?
1. Humans ingest ova in food/H2O
2. Embryo penetrates intestwall
3. Embryo goes to muscles, organs and prefers the brain.
4. Cysticercus larva develops and dies - remove surgically.
Where is T. solium mostly seen?
In Mexico and central America - don't eat the tacos!! Might get a brain cysticercus larva
What symptoms are seen in humans with Taenia solium infection?
Vague abdominal pain/diarrhea

If Cysticercus larvae, depends on lodging site.
How is T. solium diagnosed?
By finding Ova + Proglottids
and Cysticercus cellulosae
-Can serological test for Ab
How can you prevent T. solium?
By cooking pork well, inspecting it before eating, disposing human feces well, personal hygiene.
What would make a T. solium infection worse?
Antiparasitic drugs - cause a hyperimmune reaction
What cestode is most likely to infect humans?
Diphylabothrium latum - causes fish tapeworm disease and pernicious anemia.
What is characteristic morphology of Diphyllobothrium latum?
Where is it found?
It's a broad tapeworm with Almond-shaped scolex.

In freshwater lakes
What are D. latum hosts
Defin: Humans, dogs, cats, bears

Intermed: Freshwater copepod and fish
What's particularly interesting about the intermed hosts of D. latum?
it HAS to have 2 intermed hosts; Freshwater copepod bug
Some other fshwater fish
What type of larva infects each intermediate host of D. latum?
Copepod: procercoid larva
Fresh Fish: Pleurocercoid larvae
what is the infectious stage of D. latum?
The pleurocercoid larva in fish.
How long are D. latum adults?
How many proglottids/strobilum?
over 10 METERS!! longest
over 3,000 proglottids/strob.
What does the D. latum ovum look like?
-about 70x45 u
-Has an operculum that opens when the larva's ready to leave.
-Sometimes a thickening at butt.
What symptoms are seen in Diphyllobothriasis?
Vague GI problems
Pernicious anemia
-VitB12 defic. Macrocytic RBCs Hypersegmented PMNs - NO eosinophilia
How is D. latum infection diagnosed?
Ova in stool
Pernicious anemia
How is D. latum prevented?
Don't eat raw fish
Don't put human feces in freshwater
what is the nickname for disease caused by Hymenolepis nana?
Dwarf tapeworm infection

ohh poor snow white her friends get tapeworm too
What's unique about dwarf tapeworm infection?
-the only tapeworm that doesn't require an intermediate host.
What's the definitive host of Hymenolepis nana?
Humans and rodents
What are the intermediate hosts of Hymenolepis nana?
Why - what stage do they house?
They AREN'T required but can be:
-Fleas and beatles
-House the cysticercoid larva
how long are h. nana adults?
-Adults are only 35 mm and several may be in one infection.
-Ova are 45x35u
How does the H. nana ovum compare to the H. diminuta?
-H. nana is smaller -45u, where H. diminuta is about 75u diam.
-Both have hexacanth embryo w/ 6 hooks
-Only NANA has four polar filaments/thickenings
-Only DIMINUTA has yolk mtrl around the developing embryo.
What type of pathology do both Hymenolepis species give?
Vague abdominal, rare.
How are both Hymenolepis species diagnosed?

Ova in stool

Good hygiene
Does Hymenolepis diminuta require an intermediate host?
YES - insects, housing the cysticercoid larva.
What is the formal name for dog tapeworm?
Dipylidium caninum
What are the hosts of D. caninum
Defin: Dogs, cats, wild carnivores, sometimes humans

Intermediate: Fleas and lice
How is the D. caninum ovum unique?
IT forms an EGG PACKET of 20-30 eggs per gelatinous capsule.
What symptos does dog tapeworm cause?
How is it diagnosed?
How is it prevented?
Usually asymptomatic
Diagnosis: egg packets in stools
Prevent: treat fleas/lice
What are the two names for diseases caused by Echinococcus granulosus?
-Hydatid cyst disease
Where is Echinococcosis seen?
in sheep and cattle-raising countries like Australia and New Zealand.
Currently: Kenya.
What are the definitive hosts of Echinococcus granulosus?
Dogs, wolves, coyotes and foxes.
What are the intermediate hosts of Echinococcus granulosus?
Humans, sheep, cattle, horses and hogs.
How big is the E. granulosus adult? Which host is it found in,
about 2.5-9mm
found in definitive host.
What is characteristic morphology of an E. granulosus infectin?
Hydatid cysts found in body tissue (anywhere)
what is the life cycle of echinococcosus?
-Humans ingest ova from soil
-larvae hatch in sm. intestine
-larvae penetrate intestine wall and spread through body.
-hydatid cysts develop in tissue.
What 2 stages of echinococcosus can be seen?
Primary cysts
Secondary cysts
What are symptoms of the 2 stages?
Primary: most primary cysts develop in liver - hepatomegaly

Secndry: devlp anywhere - lungs, kidney, brain, bone. Can cause Anaphylactic shock.
How is Echinococcosus diagnosed?
(4 indications/tests)
-Body scans to find cysts
-Sputum/urine microscopic exam for protoscolices
-Serological testing
How is echinococcosus treated?

-surgical removal of cysts
maybe Mebendazole.

-Reduce infected dogs, properly dispose dead animals
What are the unique structures in the hydatid cyst?
-Protoscolices - sacs containing 6 hooklets

-Daughter cysts
What are the 3 RARE cestodes?
-Echinococcus multiocularis
-Multiceps species
What should I know about E. multiocularis?
It causes similar symptoms to E. granulosus
What two species cause Sparganosis and what happens in it?
Spirometra mansonoides
Diphyllobothrium other thn latum
-Humans accidently become intermediate hosts, larvae form in tissues.
-Comes from Southeast Asia.
What should I know about Multiceps species?
-Larvae form in the CNS

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