Cestoda Chapter 3.
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Transcript of Cestoda Chapter 3.
Cestoda Chapter 3 Learning Objectives State the general
characteristics of thephylum Platyhelminthes. Describe the general
morphology of anadult cestode. State the methods of diagnosis used
toidentify cestode infections. Compare and contrast the
phylumNemathelminthes with Platyhelminthesusing morphologic
criteria. Learning Objectives Define terminology
specificallyrelated to the Cestoda. State the scientific and
commonnames of cestodes that parasitizehumans. Describe in graphic
form the generallife cycle of a cestode. Differentiate adult
Cestoda usingmorphologic criteria. Learning Objectives
Differentiate larval stages of Cestodausing morphologic criteria,
therequired intermediate host, or both. Differentiate the
diagnostic stages ofthe Cestoda. Discuss the epidemiology
andmedical importance of cestodezoonoses. Learning Objectives Given
illustrations or photographs,identify the diagnostic stages
ofCestoda and the body specimen ofchoice to be used for examination
ofeach. Identify the stage in each life cyclefor each cestode that
can parasitizehumans. Introduction Classification General body
structure
Platyhelminthes (flatworms ) Cestodes ( tapeworms) General body
structure Scolex Hooks Suckers Rostellum Neck Proglottids Immature,
mature, gravid (proglottids) Reproduction - Hermaphroditic Tapeworm
body Tapeworm body Tapeworm body Tapeworm body Tapeworms infecting
humans
Hymenolepsis nana-- dwarf tapeworm Taenia saginata beef tapeworm
Taenia solium pork tapeworm Diphyllobothrium latum broad
fishtapeworm Echinococcus granulosis hydatid tapeworm Hymenolepis
nana (dwarf tapeworm)
Method of diagnosis Diagnostic stage Disease name Major pathology
and symptoms Treatment Distribution H. nana Tropics and sub tropics
Children and institutionalized people
Most common tapeworm in U.S. Requires no intermediate host
Autoinfection is common Mice can be definitive host Eggs in feces
infective stage Fleas & beetles transport hosts Cysticercoid
larva infective stage Hymenolepis nana - (dwarf tapeworm) H. Nana
egg - Diagnostic Stage H. Nana egg - Diagnostic Stage H. nana Small
scolex Rostellum with 1 row of hooklets Taenia saginata (beef
tapeworm) and Taenia solium (pork tapeworm)
Method of diagnosis Diagnostic stage Disease names Major pathology
and symptoms Treatment Distribution Taenia Life Cycle Taenia eggs
Taenia saginatta (beef tapeworm) Life cycle Taenia solium Lifecycle
T.Solium (pork tapeworm) armed-
4 suckers Rostellum 20-30 largehooks set in 2rows T. Saginata (beef
tapeworm) Unarmed- 4 large cup-shaped suckers T. solium Uterus 7-13
lateral branches Eggs are infective T. saginata Uterus 15-30
lateral branches Diagnostic - Identification Diphyllobothrium latum
(broadfish tapeworm)
Method of diagnosis Diagnostic stage Disease names Major pathology
and symptoms Treatment Distribution D. latum D. latum Worldwide
freshwater Florida, Great Lakes, Alaska
Often asymptomatic ; vague GIdisturbance Macrocytic, pernicious
anemia Competes with host for Vitamin B12 D. latum Scolex No Hooks
or cup-shaped suckers
Bothria- 2grooved suckerson eithersideofscolex D. latum Operculated
egg with terminal knob D. Latum egg D. latum D. latum proglottid
Rosette shaped Uterus Echinococcus granulosus (hydatid tapeworm)
(dog tapeworm)
Method of diagnosis Diagnostic stage Disease names Major pathology
and symptoms Treatment Distribution Echinococcus granulosus
Onlyfound in canine host(DOG OR WOLF ISDEFINITIVE HOST)
Intermediate host sheepor other ruminants Human is
accidentalintermediate host Eggs ingested Contaminated food orwater
Objects contaminatedwith dog feces Dog becomes infected byeating
raw meatcontaining hydatid cyst E. Granulosus hydatid cyst with 3
brood capsules E. Granulosus hydatid cyst
Each scolex has suckersand crown of hooks Each scolex grows toadult
tapeworm ifingested by dog E. Granulosus hydatid cysts from
vertebral column (bone)
Humans cysts in any tissue mostcommon Liver Lung Central nervous
system (CNS) Bone bone marrow Disease varies with location ofcysts
- No symptoms or death Disease may develop slowly Slow-leaking cyst
allergicsensitization Cyst rupture anaphylaxis ordissemination E.
Granulosus Rare in Europe or U.S. except in sheep raising
areas
Southwest ( Navajo) ; Utah Common in Alaska and Canada Diagnosis
history of exposure Radiology X-ray, ultrasound, CT
Immunodiagnostic skin testing Serology indirect hemagglutination,
ELISA Hooklets, scolices,, cyst membranes in histology tissue preps
orbodyfluids Hydatid sand- granular material found in older cysts;
free scolices,daughter cysts ; hooklets Biopsy dangerous cyst
leakage causes anaphyaxis Zoonoses Cysticercosis Echinococcus
granulosus
Dipylidium caninum (dog or cat tapeworm) Human accidentally ingests
larva from infected dog orcat flea (IH) Mild infection adults in
intestine; egg packets orproglottids in feces Hymenolepsis diminuta
( rat tapeworm) Human accidentally ingests larva from infected flea
orgrain beetle (IH) Mild symptoms; often resolves spontaneously;
eggs infeces are diagnostic Cysticercosis Echinococcus granulosus
H. Diminuta vs H. nana H. Diminuta vs H. nana Zoonoses
Dyphlobothrium spp. (dog or cat species)
Location of parasite in humans How infection occurs Disease
symptoms Diagnosis