Helminths Flashcards
What are some characteristics of Helminthic parasites?
- Complex lifecycles, often needed an intermediate host
- Dioecious or monoecious (hermaphroditic)
What are the 3 categories of helminths and their common names?
- Nematode (Roundworms)
- Trematode (Flukes)
- Cestodes (flat or tapeworms).
What is the lifecycle of Taenia Saginata and what does it cause?
Beef Tapeworm, with cattle as intermediate host, and humans ingest cysticerci in under cooked meat. Adults attach in intestinal epithelium.
Can cause malnutrition, or rarely if humans act as intermediate, Cysticercosis (larvae invade tissue).
What is the lifecycle Taenia solium and what does it cause?
Pork tapeworm. Same as beef tapeworm, with intermediate host as a pig.
What is the lifcycle of Echinococcus granulosus and what does it cause?
Tapeworm of canines. Canines infected by eating cysticerci in herbivore hosts. Causes hydatid disease, where cysts form throughout the body.
What are the key characteristics of Trematodes?
- Flat, leaf-shaped worms
- Lack complete digestive system.
- Oral and ventral suckers to attach and get nutrients
- Grouped according to site in body they parasitize.
What are the key characteristics of Schistosoma? Also called?
- Most important trematode infection of humans, with over 200 million people infected.
- Motile cercariae in fresh water penetrate intact skin, migrate via circulation to liver.
- Male-female pair migrate to veins in intestine and bladder to release eggs.
- Called Blood Flukes.
What is the lifecycle of Schistosoma? Causes?
Eggs hatch and larvae penetrate snails, Released into water, penetrate skin, lost tails, larvae migrate to lungs heart, and then liver to mature. Migrate to mesenteric vessels and release eggs in stool.
Causes Schistosomiasis, or Snail Fever.
What is the symptoms of Schistosoma infection?
Infection are asymtomatic early on. First response is TH1, Egg-layinng gains TH2 response, with granulomas surrounding the eggs. can lead to cirrhosis.
What are the key characteristics of Nematodes?
- Long, Cylinrical roundworms tapered at each end
- Posses complete GI tract, have protective cuticle
- All are dioecious
- Females larger than males
What is the lifecycle of Roundworms?
Parasites of all vertebrates.
Most intestinal nematodes shed eggs in intestine to be released in feces.
Some released into coil, where larvae can penetrate skin.
Some ensyst in muscle tissue and are consumed.
Mosquito can transmit a few species.
What are the characteristics of Ascaris lumbricoides?
-Largest and most common nematode infection.
-Rural areas of SE US
-Can migrate and be expelled out of anus, or coughed up out of mouth.
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What is the lifecycle of Ascaris lumbricoides? Causes?
Eggs are ingested, larvae enter blood, go to lungs, coughed up, ingested, and mature in intestine. Often causes intestinal blockage and is fatal.
What are the characteristics of Trichuris trichiura? Also called? Lifecycle?
AKA whip worm.
- Lives in large intestine down to rectum
- threaded through mucosa
- Eggs to soil to mouth hatching to adults in intestine.
What are some symptoms of Thricuris trichiura?
Dysentery, anemia, growth retardation, tenesmus, prolapsed rectum.
