Cestodes and Trematodes Flashcards
List general characteristics of the Cestodes
- Flatworms (members of Platyhelminths)
- Scolex (head) w/ suckers, some w/ hooklets (“armed”)
- Proglottids (segments) can be diagnostic for some (most are hermaphroditic → eggs produced in each mature proglottid)
- All requires 1 or more intermediate hosts
- Eggs or glottids passed in stool
List general characteristics of Trematodes
- Adults are leaf-like and flat (Platyhelminths)
- Human (or another animal) is definitive host for all
- Two intermediate hosts for most (schistomsomes have one)
- Eggs is diagnoistic stage
- Flotation methods aren’t effective for detection
Of the cestodes and trematodes discussed in class, which ones are present in the U.S.?
Cestodes: - Hymenolepis nana - Diphyllobothrium latum - Taenia sagniata, Taenia solium - Echnicoccus granulosus Trematodes - Fasciola hepatica
Diagnostic form of Hymenolepis nana
Eggs
Microscopic examination of Hymenolepis nana eggs
Thin-shelled in stool (30-45um) w/ hexacanth embryo, polar thickenings and filaments
Diagnostic form of Hymenolepis dimunute
Eggs
Microscopic examination of Hymenolepsis diminute eggs
Hexacanth embryo w/ no polar filaments (70-85um), larger and thicker shelled than Hymenolepis nana
Diagnostic form of Diphyllobothrium latum
Eggs or proglottids passed in stool
Microscopic examination of Diphyllobothrium latum
- Eggs: Operculate, shoulders, aboperculate knob (65um)
- Proglottids are more broad than long
- Scolex has bothria (slits) instead of suckers
Diagnostic form of Taenia saginata
Eggs or proglottids passed in stool
Microscopic examination of Taenia saginata
- Eggs (40um), striated shell, hexacanth embryo (can’t differentiate from T. solium)
- Proglottids are longer than wide (15-30 uterine branches), scolex has no hook
Diagnostic form of Taenia solium
Eggs or proglottids found in stool
Microscopic examination Taenia solium
- Eggs cannot be differentiated from Taenia saginata
- Proglottids are similar to Taenia saginata except they have 7-12 uterine branches
- Scolex is armed (hooks”
____ is caued by a bladder worm filled w/ scolex
Cysticercus
Diagnostic form of Echinococcus granulosus
Aspirate fluid from cysts containing scolices and hooklets (“hydatid sand”)
Diagnostic form of Dipylidium caninum
Eggs and proglottids
Microscopic examinaiton of Dipylidium caninum
- Egg packets containing numerous hexacanth embryos
- Proglottids resemble cucumer seeds or rice grains
Diagnostic form of Fasciolopsis buski
Eggs
Microsocpic examination of Fasciolopsis buski
Eggs are very large (130um), operculate, can’t be differentiated from eggs of Fasciola hepatica
Diagnostic form of Fasciola hepatica
Eggs in stool
Microscopic examination of Fasciola hepatica
Eggs are very large (130um), operculate, can’t be differentiated from eggs of Fasciolopsis buski
Diagnostic form of Clonorchis sinensis/Opisthorchis spp.
Eggs
Microscopic examination of Clonorchis sinensis/Opisthorchis spp
Eggs are very small (30um), operculate, flask shaped → found in stool/biopsies (“shoulders”, “abopercular knob”)
Diagnostic form of Paragonimus westermani
Eggs
Microscopic examination of Paragonimus westermani
Eggs are small (90um), operculate in sputum (or feces); often “shoulders”, aboperculate thickening but no knob
Diagnostic form of Schistosoma
Eggs
Microscopic examination of Schistosoma japonicum
Eggs are 85um, rounded and have a lateral spin
Microscopic examination of Schistosoma mansoni
Eggs are 150um, elongated, long pointed lateral spine
Microscopic examination of Schistosoma hematobium
Eggs are 150um, elongated, pointed terminal spine
Common name for Hymenolepis nana
Dwarf tapeworm
Common name for Hymenolepis dimunta
Rat tapeworm
Common name for Diphyllobothrium latum
Broad fish tapeworm
Common name for Taenia sagniata
Beef tapeworm
Common name for Taenia solium
Pork tapeworm
Common name for Echinococcus granulosus
Canine tapeworm
Common name for Dipylidium caninum
Dog tapeworm
Common name for Fasciolopsis buski
Giant intestinal fluke
Common name for Fasciola hepatica
Large liver fluke, sheep liver fluk
Common name for Clonorchis sinensis/Opisthorcihis spp
Oriental or Chinese liver fluke
Common name for Paragonimums westermani
Oriental lung fluk
Common name for Schistosoma spp
Blood flukes
Major clinical manifestations corresponding w/ Hymenolepis nana?
Asymptomatic
Major clinical manifestation corresponding w/ Hymenolepis diminuta
Few symptoms unless heavy parasite burden
Major clinical manifestations corresponding w/ Diphyllobothrium latum
Megaloblastic anemia (competition for Vitamin B12)
Major clinical manifestations corresponding w/ Taenia saginata
Vague GI symptoms
Major clinical manifestations corresponding to larvae ingestion fo Taneia solium
Intestinal
Major clinical manifestations corresponding to larvae ingestion fo Taneia solium
Cysticercosis (larvae in fluid-filled bladder)
Major clinical manifestations corresponding to Echinococcus granulosus
Cysts in liver, lung, brain, CT scan/surgery
Major clinical manifestations of Fasciolopsis buski
GI obstruction w/ heavy infections, edema, malabsorption
Major clinical manifestations of Fasciola hepatica
In humans, larvae migrate from intestine to liver causing major destruction, fibrosis, partial obstruction of bile ducts
Major clinical manifestations of Clonorchis senensis/Opisthorchis spp
Pain, bild duct obstruction, jaundice (associated w/ liver/gall lbalddercancer)
Major clinical manifestations of Pragoniums westermani
Chronic cough, hemoptysis (“iron filings”), pulmonary fibrosis, resembles TB
Major clinical manifestations of Schistosoma spp
Local irritation t penetration site; major symptoms dependent on fluke’s life cycle
Hymenolepis nana
- Intermediate host(s)
None or infected arthropods
Hymenolepis diminuta
- Intermediate host(s)
None
Diphyllobothrium latum
- Intermediate host(s)
Copepod and freshwater fish
Taenia saginata
- Intermediate host(s)
Cattle
Taenia solium
- Intermediate host(s)
Pigs
Echinococcus granulosus
- Intermediate host(s)
Sheep
Dipylidium caninum
- Intermediate host(s)
Canines
Fasciolopsis buski
- First intermediate host
- Secondary intermediate host
- First: snail
- Second: water plants (water chestnuts, bamboo shoots)
Fasciola hepatica
- First intermediate host
- Second intermediate host
- First: snail
- Second: water plants (watercress)
Clonorchis sinensis/Opisthorchis spp
- First intermediate host
- Second intermediate host
- First: snails
- Second: freshwater fish (raw, smoked, pickled, or dried)
Paragonimus westermani
- First intermediate host
- Second intermediate host
- First: snails
- Second: crabs or crayfish
Schistosoma spp
- First intermediate host
Snails
Which method, flotation or sedimentation, is better for isolating cestodes and/or trematodes?
Most trematodes and cestodes have “caps”. If you remove the “cap”, they sink. Therefore sedimentation method is best
Fasciolopsis busk
- Infective site
Intestines
Fasciola hepatica
- Infective site
Liver
Clonorchis sinensis/Opisthorchis spp
- Infective site
Liver
Paragoniumus westermani
- Infective site
Lungs
Schistosoma spp
- Infective site
Blood
Most common Cestode found in the U.S.
Hymenolepis nana
Disease typically caused by Dipylidium caninum
Heartworm in dogs
Human patient population mostly affected by Dipylidium caninum
Children from accidental ingestion
Appearance of Dipylidium caninum
Egg packets → hexacanth embryo; proglottids resemble cucumber seeds or rice grains
All Schistosoma larvae undergo part of their life cycle in a snail. How are humans infected?
Larvae are released from the snails and the larvae penetrate through the skin