Download presentation
1
Class Cestoda: The tapeworms
Exclusively endoparasites Body covered by a tegument Body consists of an anterior scolex, followed by a short neck and then a strobila composed of a series of “segments” or proglottids. Digestive track absent.
2
Scolex, anterior holdfast organ
Neck, region of growth Strobila made up of individual proglottids. Three types of proglottids: immature, mature and gravid.
3
SEM of a Scolex
4
Diversity of scolexes.
5
Adult Tapeworms
8
You will be responsible for 2 orders of tapeworms!
Phylum Platyhelminthes Class: Cestoidea Subclass Eucestoda Order Pseudophyllidea Order Cyclophyllidea
9
Life Cycles Adult tapeworms live in the intestine of vertebrates specifically the small intestine. Eggs pass in the feces of vertebrate host. Larval stage in egg = onchosphere. It is spherical and has 6 hooks (hexacanth).
10
Generalized Pseudophyllidean Life Cycle Aquatic Life Cycle
11
Adult in Vertebrate Small Intestine
Uterine pore Eggs released; later chains of spent proglottids
12
Eggs are usually operculated and unembryonated when laid.
13
The first larval stage the Coracidium
The oncosphere develops in the egg and a free swimming larva the Coracidium hatches. The first larval stage the Coracidium
14
Coracidium
16
The free swimming coracidium is eaten by 1st intermediate host usually an aquatic arthropod!
Copepod
17
In the copepod the second larval stage (PROCERCOID)
Frontal glands Cercomer posterior end
18
2nd IH is a vertebrate of some kind (usually cold blooded)
19
The 3rd type of larva that develops in the 2nd IH is the PLEROCERCOID
The cercomere is lost and a scolex develops (no proglottids)!
22
Life cycle of Ligula intestinalis
23
Generalized Cyclophyllidean Life Cycle Terrestrial Life Cycle
24
Adults live in the small intestine of vertebrates.
25
Eggs passed not by uterine pore but instead by short chains or terminal proglottids that split open to release eggs!
26
Only one IH can be vertebrate or invertebrate depending on species of tapeworm!
The type of larval stage that develops varies depending on species of tapeworm! Cysticercoid Cysticercus Strobilocercus Coenurus Hydatid Alveolar hydatid
27
Cysticercoid Anterior vesicle with scolex invaginated; solid posterior with tail-like region; in arthropods!
28
Cysticercus Central cavity; fluid-filled; invaginated scolex; in reptiles or mammals, rarely birds!
29
Cysticercus
30
Strobilocercus Strobiloceroid-a simple cysticercus in which some strobilation occurs in the cyst.
31
Coenurus Bladder with multiple scolices; in mammals; hydatid cyst a special case!
32
Hydatid Cysts Secondary brood cysts
33
Hydatid Cysts
34
Alveolar Hydatid Cysts
Alveolar hydatid cyst in a mouse - cyst metastasizes from the liver to fill the body cavity
35
Pseudophyllidea
36
Diphyllobothrium latum
Broad fish tapeworm Fish eating mammals Scandinavia, Baltic States, Russia, Great Lakes, West coast of N. America unusual 9 million people infected 10 meters long 1 million eggs per day
37
The broad fish tapeworm Life cycle of Diphyllobothrium latum
Plerocercoid Coracidium Procercoid
38
Pike and salmon common hosts
Paratenic host
39
Pathology and Symptoms
Attaches to small intestine Pathogenicity varies Asymtomatic Abdominal discomfort, diarrhea, nausea Megaloblastic Anemia (caused by loss of vitamin B12) Worms absorb vitamin B12 Disrupt host ability to absorb B12 Finland
40
Diagnosis and Treatment
Look for ___________________in feces. Praziquantel
41
Epidemiology How do you get infected with Diphyllobothrium latum?
What else should we be concerned about? Fish ponds
42
Life Cycle of Spirometra (Diphyllobothrium) mansonoides
Adult tapeworm occurs in the small intestine of a cat the definitive host.
43
Frog second intermediate host containing the plerocercoid
44
Spirometra (Diphyllobothrium) mansonoides
Unusual causes a great increase in size of a mammalian second intermediate host (mice).
45
Sparganosis
46
Human Infections of Spirometra (Diphyllobothrium) mansonoides
A few cases in the US have involved finding plerocercoids in the eyes.
47
Human Infections of Spirometra (Diphyllobothrium) mansonoides
Parasite is rare - only about 40 cases of human sparganosis have been reported in the U.S.
48
Sparganosis Disease Humans infected with plerocercoid Ingest copepod
Eating raw meat with plerocercoids Plerocercoid transfers to human Frog or snake flesh poultice Pluerocercoid moves into human tissue
49
Sparganosis Seriousness depends on Removed by surgery
Where plerocercoid establishes Number If reproduction occurs Removed by surgery
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.