0:00 Helminths is a general term used to describe a type of parasitic worm that can 0:10 infect and 0:10 live in various organisms, including humans. 0:15 To recap, parasites can be divided into three main types. 0:19 You have the protozoa, the helminths, which we'll focus on, and the ectoparas 0:25 ides. 0:26 This comes from the Greek word "helminths", which means intestinal worm. 0:30 Today, they refer to worms that not only cause problems in intestines, but also 0:35 other organs 0:36 such as the lungs and the liver. 0:40 Helminths are large, multicellular organisms that are generally visible to the 0:45 naked eye 0:46 in their adult stage. 0:48 Like protozoa, helminths can be either free-living or parasitic in nature, 0:53 meaning they 0:54 could live in the environment, or they can infect humans, parasitic. 1:04 Helminths are classified into three types. 1:08 Flukes, called trematodes, tapeworms, called cestodes, and roundworms, called 1:17 nematodes. 1:18 Flukes and tapeworms are also known as flatworms to make things confusing, but 1:22 it's also quite 1:24 easy because both these helminths, worms, they're all very flat. 1:30 So let's talk about each one of these three types of helminths in more detail, 1:35 beginning 1:35 with flukes. 1:38 So flukes, also known as trematodes, are leaf-shaped flat worms. 1:43 They're flat. 1:45 Majority are hemaphrodites, meaning they have both male testes and female 1:50 uterus, reproductive 1:51 organs in the same person. 1:56 The schistosomes are the only trematodes which have different sexes, so they 2:02 individually 2:03 have male and female reproductive organs. 2:09 Trematodes have two suckers, mouth openings, one oral and one ventral, which 2:15 help them 2:15 to move and anchor to host tissue. 2:20 The mouth openings form their digestive tract, which, funnily enough, ends sort 2:26 of blindly. 2:27 Trematodes, therefore, have an incomplete digestive tract. 2:31 They usually regurgitate things back out. 2:35 Trematodes' bodies are covered with tegment, which is usually armed with scale- 2:41 like spines. 2:42 The tegment allows for the absorption of nutrients and excretion of waste. 2:48 The two suckers allow the adult worm to attach and move around in the 2:53 definitive host, such 2:54 as the human, for example. 2:56 And they could attach to things such as the lungs, liver, and the stomach. 3:01 Sources of transmission of human infection include fish, crustaceans, and 3:10 aquatic plants. 3:13 There are many types of trematodes, or flukes. 3:17 Different species of flukes tend to infect different parts of the human body. 3:23 And this is a good way to classify the trematodes or the flukes. 3:27 You have blood flukes, which are the schistosomes, the liver flukes, which are 3:32 the clonorchis, 3:34 lung flukes, paragonemus, and intestinal flukes. 3:38 The next type of helmin are the tapeworms, also known as the cestoids. 3:51 Tapeworms are another type of flatworm, they're flat. 3:55 Adult tapeworms are elongated, segmented flatworms. 4:00 They're also hermaphrodites. 4:03 The head has one or more hooked suckers for firm attachment to the host. 4:10 Behind the head is the neck, which is the growing region. 4:14 The body consists of segments, called proglotid, each containing reproductive 4:20 organs. 4:21 And because they're hermaphrodites, they contain both male and female 4:26 reproductive organs. 4:29 Neck is an unsigmented region with high regenerative capacity. 4:35 If treatment does not eliminate the neck, the entire worm can actually 4:40 regenerate and 4:41 grow. 4:43 Tapeworms have no digestive system, no mouth, no anus. 4:47 The digested food of the host is absorbed through the body wall of the tapeworm 4:53 s. 4:53 The life cycle of tapeworms is complicated and actually involves one, two, or 4:57 three intermediate 4:58 hosts. 5:00 Important tapeworms that infect humans can be grouped into those that infect 5:05 the intestines 5:06 and those that infect other tissues, other organs. 5:11 Tapeworms which typically infect the gastrointestinal tract genre include difil 5:17 obothrium, hemenolipis, 5:20 tenia, tapeworms genre that infect other tissues include echinococcus. 5:31 Now the third and last type of helminth are the roundworms, called nematodes. 5:36 Roundworms are cylindrical worms, they have a complete digestive tract. 5:41 They are not flat, they are cylindrical and round, and so they contain a body 5:47 cavity. 5:48 They inhabit intestinal and extra-intestinal sites within our bodies. 5:53 Roundworms can either gain entry to the host by egg ingestion, such as tricuras 6:00 , enterobius, 6:02 and escharis. 6:04 And then there are those that are capable of producing lava that then penetrate 6:08 the 6:08 skin of their host, such as strontoloidies, or produce lava that then penetrate 6:14 the mucosa, 6:15 such as with escharis. 6:23 Roundworms can actually be classified easily based on their life cycles. 6:27 So you have group 1. 6:30 Group 1 roundworms are those that attach and grow in the intestines soon after 6:35 being ingested, 6:36 and these include tricuras and enterobius. 6:42 Group 2 are the roundworms that first penetrate the venous system, either via 6:47 the skin or via 6:49 the intestine. 6:50 They then enter the lungs and then migrate up the bronchi to the trachea where 6:54 they will 6:54 be swallowed again into the intestines. 6:57 And this group include escharis, strontoloidies, and the hookworms, and silost 7:05 oma, duodenale, 7:07 and nakato americanos. 7:15 So those are three groups of helmets, broadly speaking. 7:19 But within each of these groups, there are those that are also referred to as 7:24 soil transmitted 7:25 helmets. 7:26 Now, soil transmitted helmets are a group of parasitic worms that infect humans 7:30 through 7:31 contaminated soil, and these worms are commonly found in areas with poor sanit 7:36 ization and 7:37 hygiene practices, especially in tropical and subtropical regions. 7:41 The most common types of soil transmitted helmets include escharis, lumbricoid 7:49 ies, hookworms, 7:51 the ancyclostoma, duodenale, and nakato americanos, and the whipworm, tricuras, 8:05 tricura. 8:05 Now moving on to diagnoses. 8:07 The diagnoses of helmets is generally made by examining the stool or tissues of 8:13 specific 8:14 organs, looking for eggs, larvae, or the adult worm forms. 8:20 And this is usually identified through a microscope. 8:23 Treatment of helmets infection is with antiparasitic medication. 8:33 So in summary, helmets are large multicellular organisms that are generally 8:37 visible to the 8:38 naked eye in their adult stage. 8:40 Like protozoa, helmets can either be free-living or parasitic in nature, 8:44 meaning they could 8:45 live in the environment, or they can infect humans. 8:49 Helmets are classified into three types, flukes, the trematodes, tapeworms, the 8:52 cestoids, 8:53 and roundworms, the nematodes. 8:56 If we draw a table here, we can briefly summarize each of their characteristics 9:02 . 9:02 So first and foremost are the trematodes. 9:08 Their shape is unsegmented. 9:12 They have no body cavity because they're flat, they have an incomplete 9:15 digestive tract, and 9:17 they're hemaphrodites, except for schistosoma. 9:22 The cestoids, also known as the tapeworms, these guys have a segmented plane 9:30 without 9:31 a body cavity because they're flat, and they do not have a digestive system, 9:36 and they're 9:36 also hemaphrodites. 9:38 The final ones are the roundworms, or the nematodes. 9:42 These guys are cylindrical, they do contain a body cavity, and they have a 9:49 complete digestive 9:51 tract, and they're either male or female. 9:55 Thank you for watching. 10:01 �
