Properties of Tapeworms (Cestodes)
Second Major Group of Flatworms
Segmented body, lack a gut or a mouth, 3 pairs of posterior hooks
Found in
... [Show More] Digestive Tract
Life Cycle typically has 2 hosts, sometimes 3
Must be eaten to infect a host
Hermaphroditic
Each body segment is a reproductive unit
Aquatic & Terrestrial Lifecycles
Properties of Trematodes (Flatworms) aka Digenia/Flukes/Platyhelminthes
Approx. 1mm to 5cm long, soft bodies, attach with suckers
Complex lifecycle with 2 distinct generations (miracidium & cercariae)
Mostly hermaphroditic
Snails are obligate 1st intermediate host (near water!)
Vertebrates are 2nd intermediate and adult hosts
Common in aquatic vertebrates or wet climates
Properties of Protozoa
Flagellates, Amoeba, & Apicomplexa
Taxonomy controversial and constantly changing
Polyphyletic (Flagellates & Amoeba) & Monophyletic (Apicomplexa)
Properties of Flagellates
Diplomonads (Giardia), Trichomonads, & Trypanosomes
Any protozoan, at some point in it's lifecycle has 1+ flagella
Typically treated with Metronidazole
Properties of Amoeba
Obligate (enteric pathogens) & Facultative (enteric commensals & free-living opportunists)
Typical Fecal/Oral Life cycle (cysts & trophs)
Lesions start in gut then spread to other organs
Diagnosed through stool examination
Treated with iodoquinol, paromomycin, metronidazole or tinidazole
Properties of Apicomplexa (Alveolates)
Ciliates, Microsporidia, & Blastocystis
Apical complex: group of organelles on one end of the organism that allows it to penetrate the host cell
Many diff. genus (intestinal, extra-intestinal, & blood)
Monophyletic, arose from marine environment
Either Monoxenous (one host) or heteronxenous (more than one host)
Proglottids
Body Segments of a Tapeworm
Each contains a sexually mature reproductive system
Scolex
Head of a Tapeworm
Contains Suckers or hooks for adhering to the gut
Strobila
Segments of tapeworms made of multiple proglottids
Why they are referred to as "tape"worms
Mode of Transmission
Trophic
Parasites transfer from one host to the next by being eaten
Coracidium
Egg embryonates to enter the first larval State of Tapeworms
Procercoid
First intermediate host
Coracidium is eaten by copepod and develops into procercoid
Plerocercoid
Second Intermediate/ Paratenic Host
Infective form found typically in the tissue and organs of host
Metacestode
Tapeworm larva infective to definitive host by ingestion
Many different types, some asexual
Oncosphere
Embryo common to all Tapeworms
It has hooks to penetrate gut of intermediate hosts
Types of Metacestodes
Cysticercus, Cysticercoid, Coenurus, Strobilocercus, Hydatid, & Procercoid [Show Less]