cestodes

general characteristics of cestodes

• aka tapeworms

• infect intestinal tract, any tissue, or organ

• class:cestoda

• found worldwide

• hermaphroditic organism

life cycle of a cestode

usually require an intermediate host

adult cestodes characteristics

• ribbon like body (strobila

• 3mm-10m

• scolex (head)

• rostellum (tip of head)

• proglottids (added body segments for growth)

egg cestodes characteristics

• contake oncosphere

• embryo with 3 hooks

diphyllobothrium latum

• aka fish tapeworm or broad fish tapeworm

• longest adult tapeworm

• primarily seen in great lakes

• adults can be 10 m long

transmission of diphyllobothrium latum

• ingestion if plerocercoid larvae in pickled raw undercooked fresh wtar fish

• humans harbor only one single worm

clinical infection of diphyllobothrium latum

• usually asymptomatic

• vague symptoms- sometimes nausea vomiting intestinal irritation

• may cause vitamin b12 deficiency leading to megaloblastic anemia!!!!

diphyllobothrium latum lab diagnosis

• most eften finding egg in stool specimen

• sometimes we can also find scolex and proglottids

diphyllobothrium latum egg characteristics

• yellow brown eggs

• have a operculum with a knob at the opposite end

• 58-76 micrometers by 40-50

diphyllobothrium latum scolex characteristics

• two sucking grooves

• elongated spoon shaped

diphyllobothrium latum proglottids characteristics

• wide shaped

• central rosette shaped uterus

• ivory colored

Tania saginata general characteristics

• aka beef tapeworm

• found in beed eating areas of the world

tenia solium general characteristics

• aka pork tapeworm

tenia solium and tania saginata transmission

• ingestion of raw meat containing cysticercus

• adults attach to the intestinal mucosa of small intestine

• humans may also ingest infected eggs

clinical infection for Tania saginata and tenia solum

taeniasis- vague gastrointestinal disturbances, GI spain, loss of appetite

clinical infection for tenia solium

causes major complication cysticercosis

• muscle invasion- muscle pain and weakness

• eye invasion- retinal detachment, blurred vision

• brain- neurocysticercosis- headache, convulsions, motor and sensory problems

tenia solium and tenia saginata lab diagnosis

finding of egg, scolex, and proglottid in feces

tenia solium and tenia saginata ova characteristics

• spherical and walnut brown

• 30-34 micrometers

• smooth thick sjell with radial striations in the shell

taenia saginata scolex characteristics

• 5 mm long with four suckers

• no hooks

taenia solium scolex characteristics

• four suckers

• double row of 20-30 suckers

t.saginata and t.solium proglottids characteristics

• t saginata-15-20 branches

• t.solium-7-13 branches

hymenolepis nana general characteristics

• aka dawrf tapeworm

• no intermediate host required (only the cestode)

• common in children: autoinfection life cycle (F/O)

hymenolepis diminuta

• aka rat tapeworm

• flea is intermediate host

transmission for h.nana and h.diminuta

• ingestion of infective eggs in contaminated soil

• ingestion of infected arthropod (flea)

clinical infections for h.nana and h.diminuta

• light infections- asymptomatic

• many worms- headache, irritability, dizziness, abdominal pain, diarrhea anorexia

lab diagnosis for h.nana and h.diminuta

• egg identified in feces

h. nana ova characteristics

• egg is 30-47 micrometers

• grayish color

• hollow lemon oncosphere

• 4-8 polar filaments outside oncosphere

h.diminuta ova characteristics

• ehh is 50-75 micrometers

• gray or straw colored

• hollow lemon oncosphere

adult h.nana characteristics

• 40 mm long

• small colex

• 4 suckers with rostellum spines

dipylidium caninum general characteristics

• tapeworm of cats and dogs

• humans are accidental host

transmission of dipylidium caninum

ingestion of fleas containing larva (cysticercoid stage) of parasite

dipylidium caninum clinical infection

• pets may exhibit behavior to relieve anal pruritis

• humans- usually asymptomatic, mild gastrointestinal disturbances

• complication- sparganosis

dipylidium caninum lab diagnosis

• macroscopic identification of proglottids in stool

• motile when freshly passed

• microscopic identification of eggs in stool

dipylidium caninum ova characteristics

• large egg packet

• contains 15-25 eggs

• each 20-40 micrometers in size

dipylidium caninum proglottids characteristics

• two genital spores

• ressembles pumpkin seeds

• adult worm- 10-80 cm long

dipylidium caninum scolex characteristics

• 4 suckers with armed rostellum

echinococcus granules general characteristics

• aka hydatid tapeworm

• humans are accidental host

• found worldwide, common in sheep raising areas

• definitive host- dog

• intermediate host- sheep and other herbivores

transmission of echinococcus granules

ingestion if eggs containing hexacanth embryo from food, water, or fomited contaminated with dog feces

clinical infections of echinococcus granules

causes cystic echinococcosis aka hydatid disease

• development of harmful slow growing cysts in vital organs

• organs infected-liver,lung,brain,bone,heart

• rupture of cysrs- fever, pain, urticaria, eosinophilia, and anaphylactic shock

echinococcus granules lab diagnosis

• identification of protoscoleces in tissue

echinococcus granules patient diagnosis

• diagnosis is usually made by ultrasound, CT,MRI and biopsy

• hydatid cyst in liver lung brain ect

• serologic test- EIA and immunoblot techniques

• hydatid trill- vibration of cysts

morphology of hydatid cysts

• daughter cysts bud off mother cyst

• rupture of cysts liberates foreign particles

echinococcus granules cestode

• 3-6 mm long

• contains 3 proglottids

• scolex has 4 suckers