Helminths Flashcards
Helminths
Divided into 2 phyla
Flatworms
Roundworms/Nematodes
Cestode
Tapeworm
Adult body consists of a scolex (head) and strobila (body) made from progottids in series
Scolex
Anterior end of a tapework, typically has 4 suckers and might have a rostellum
Suckers
Cup-shaped structures that aid in attachment to intestine wall
Rostellum
Fleshy extension that may or may not be armed with hooks
Strobila
Tapeworm body made of serial proglottids
Proglottid
Individual segment
Each contains male and female organs for reproduction
Hexacanth embryo/Onchosphere
Motile, first larval stage armed with three pairs of hooklets.
Egg contains an onchosphere surrounded by an embryophore
Cysticercus/Larva
Larval stage of Taenia and similar species.
Scholex with fluid-filled cyst, found in tissues of hosts
Cysticercoid/Larva
Larval stage of Hymenolopsis nana and similar species
Scholex with cyst with litter or no fluid
Coracidium
Ciliated larval stage of Diphyllobothrum latum
Emerges when egg is exposed to water
Hyatid cyst
Larval stage of Echinococcus granulosus
Taenia saginata diseases and transmission
Cestode
Transmitted from cows
Causes Taeniasis, mild abdominal symptoms
Taenia solium diseases and transmission
Cestode
Transmitted from pigs
Can develop cysticercosis as a sequellae to Taeniasis
Cysticercosis
Development of cysticerci in various sites in the body
Greatest concern is cerebral cysticercosis - seizures, mental disturbances, sudden death
Diphyllobothrium latum diseases and transmission
Cestode
Transmitted from fish
Causes diphyllobothriasis
Can be a long-lasting infection, may be asymptomatic or cause abdominal discomfort.
May cause Vitamin B12 deficiency with pernicious anemia
Trematodes
Flukes
Complex life cycles, often involve snail intermediate hosts
Fasciolopsis buski diseases and transmission
Large intestinal fluke
Transmitted via pigs and freshwater plants
Causes fasciolopsiasis
Most infections light and asymptomatic, but can cause diarrhea, etc.
Nematodes
Roundworms
Can be very long
Have highly developed reproductive system
Enterobius vermicularis diseases and transmission
Called pinworm or seatworm Common infection in schools Most common helminthic infection in US Causes Enterobiasis - perianal pruritus (itching) Transmitted fecal/oral
Ascaris lumbricoides diseases and transmission
Large roundworm "Roundworm of Man" Most common worldwide helminthic infection Causes Ascariasis Mature in intestine, lungs. Pulmonary symptoms, intestinal symptoms
Strongyloides stercoralis diseases and transmission
Threadworm (roundworm) Only females are parasitic in humans Strongyloidiasis GI symptoms Pulmonary symptoms Causes eosinophilia
