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Infections Journal. We have discussed many types of infectious agents from bacteria to viruses to protists . Is there any other disease causing pathogens we have neglected to discuss?. Let’s check out some facts! More than 25% of the worlds population is suffering from helminth infections
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Infections Journal We have discussed many types of infectious agents from bacteria to viruses to protists. Is there any other disease causing pathogens we have neglected to discuss?
Let’s check out some facts! • More than 25% of the worlds population is suffering from helminthinfections • Eggs are found in human fecal matter which can contaminate soil in areas where sanitation is poor • The greatest number of cases occur in sub-Saharan Africa, the Americas, China and east Asia • During the adult stage, this parasite bores itself into the hosts’ intestines where it feeds and grows CAN YOU GUESS WHAT HELMINTH MEANS? Helminth parasites!
“Helminth” = “worm” • Eukaryotic • Multicelluar • Invertebrates • Bilateral symmetry • w/ tube-like or flattened bodies • Triploblastic – 3 distinct layers of cells General Characteristics
Platyhelminthes (flatworms) subdivided into the Cestoda(tapeworms) and the Trematoda(flukes) 3 Main Types: Nemathelminthes(nematodes) Biodiversity trematode cestode
Long, thin, unsegmented, tube-like bodies • Anterior mouths and longitudinal digestive tracts. Nematodes (roundworms)
Fluid-filled internal body cavity (pseudocoelum) • acts as a hydrostatic skeleton providing rigidity • great and easy way to circulate nutrients Nematodes (roundworms)
Adult worms form separate sexes with well-developed reproductive systems. Nematodes (roundworms)
Nematode Infections! QUIZ Nematoda: • Ascaris • Dracunculus • Enterobius • Capillaria • Trichuris • Loa loa • Wuchereria Matching Choices: • Endemic to the Phillipines • The female sex of this organism can make up to 20,000 eggs per day! • Unlike most parasitic helminths, this species is highly prevalent in temperate zones and developed countries. • The largest intestinal roundworm • Passed on by the bite of a deer fly and can be observed nestled in the eye tissue • Very careful to remove worm in its entirety … why? • This parasite infects the lymphatic system of the host and causes swelling of the lower limbs a disease commonly referred to as elephantasis.
Nematode Infections! QUIZ
Nematode Infections! QUIZ
Nematode Infections! QUIZ
Nematode Infections! QUIZ
Platyhelminthes (flatworms) subdivided into the Cestoda(tapeworms) and the Trematoda(flukes) 3 Main Types: Nemathelminthes(nematodes) Biodiversity trematode cestode
Platyhelminthes: Cestoda Tapeworms • Live in digestive tract • Over 1,000 species have been described • Parasitize humans • consumption of undercooked meat • meat prepared in conditions of poor hygiene • Tape worm infecting humans can grow over 30ft long! • T. saginata, the beef tapeworm, can grow up 65ft! • The whale tapeworm, Polygonoporusgiganticus, can grow 100ft!
Anatomy and Identification SCOLEX • Scolex (“head”): attaches to intestines of digestive host • Includes hooks or suckers (like suction cup) • Most prominent feature but hard to identify LACK DIGESTIVE TRACT! feed off of already digested food through absorption across body “skin” PROGLOTTIDS • Body plan composed of segments called proglottids (sum of all proglottids = strobila resembles tape • Each proglottid has male and female reproductive structures • Can reproduce independently • Tapeworm a colony of proglottids?
A colony of proglottids?! • Once anchored to the host’s intestinal wall, the tapeworm absorbs nutrients through its skin as the food being digested by the host flows past it and it begins to grow a long tail, with each segment containing independent reproductive system. • Older segments are pushed toward the tip of the tail as new segments are produced by the neckpiece. By the time a segment has reached the end of the tail, only the reproductive tract is left. • It then drops off, carrying the tapeworm eggs to the next host, since, by that point, the proglottid is, in essence, a sac of eggs.
Life Cycle Includes intermediate host and primary/definite host