Tapeworms

10 Key excerpts on "Tapeworms"

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  Pests

  A Guide to the World's Most Maligned, Yet Misunderstood Creatures

  • Ross Piper(Author)
  • 2011(Publication Date)
  • Greenwood

    (Publisher)

  Platyhelminthes Cestodes Collectively known as Tapeworms, cestodes are among the largest and most well known of all the parasites that infect humans and domes- ticated animals. Humans have known about cestodes for thousands of years, and in classical antiquity, various scholars cogitated on the nature of these organisms. It is only in more recent times that we come to un- derstand the natural history of these animals, an understanding that has been accompanied by wonder and disgust in equal measure: wonder at the complexity and elegance of their lifecycle and disgust at how they damage the health of us and our animals. All the 3,500 known tapeworm species are endoparasites of vertebrates, with the adult worms taking up residence in the host’s gut. They are con- sidered to be the most evolutionarily diverse of all the parasitic flatworms, with a distinctive appearance, and ranging in size from less than 1 milli- meter to the enormous sperm whale tapeworm, Hexagonoporus physeteris, which at around 30 meters long is probably the longest invertebrate on the planet. At the head end of the tapeworm is a complex structure known as the scolex that bears a number of suckers, hooks, and spines for attach- ment to the intestinal wall. Behind the scolex is the tapeworm’s neck, which gives rise to the largest part of many Tapeworms—the strobila— a structure, actually a sequence of identical structures, unique to these animals. The strobila is devoted to reproduction and each identical unit (proglot- tid) contains at least one set of male and female gonads. The Tapeworms are hermaphrodites. The proglottids can fertilize themselves, exchange sperm with other proglottids, and even swap sperm with the proglottids of conspecifics. The proglottid at the back end of the tapeworm is mature, brimming with a cargo of egg capsules, and when the time is right the whole segment breaks off to be carried to the outside world in the host’s feces.

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  Food Safety

  The Science of Keeping Food Safe

  • Ian C. Shaw(Author)
  • 2018(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  Parasites comprise a broad array of different creatures all with one goal, to live for free! They utilise nutrients from another animal (or plant) – the host – and give nothing in return. Parasites in a food safety context have a human host as part of their complex lifecycles and are transmitted in food. They are all destroyed by cooking and so are only a problem in undercooked food (e.g. pork) or food eaten raw (e.g. fish sashimi).

  Food‐borne parasites are categorised as parasites because of their lifestyle (i.e. robbing their food from others) and not based on phylogenetics. For this reason parasites range from simple single‐celled animals (e.g. Giardia) to complex multi‐celled animals (e.g. flatworms).

  Flatworms – Platyhelminthes

  The phylum Platyhelminthes (from the Greek πλατύ (platy) meaning flat; ἕλμινς (helminth) meaning worm) includes four classes; three of them are parasites, namely cestodes (Tapeworms), trematodes (flukes) and monogenea (parasitic flatworms). Only cestodes and trematodes are human parasites.

  Tapeworms – Cestodes

  The Tapeworms have complex lifecycles usually involving at least two host species; those important as food‐borne pathogens have humans as one of the hosts. I will discuss several important food‐transmitted Tapeworms and describe their lifecycles in a little more detail below.

  The symptoms of tapeworm infection are often hunger and loss of weight. This is because the tapeworm is helping itself to the host's partly digested food as it grows in the host's gut which means that less food is absorbed by the host and so she/he feels hungry and loses weight.

  Anatomy of a tapeworm

  All of the Tapeworms have the same basic structure: they have a ‘head’ or scolex with hooks to allow the animal to hold firmly onto the intestine wall of its host, and a long, often very long (up to 5 m), segmented body (Figure 5.1

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  Parasitology

  An Integrated Approach

  • Alan Gunn, Sarah J. Pitt(Authors)
  • 2022(Publication Date)
  • Wiley

    (Publisher)

  5 Platyhelminth and Acanthocephalan Parasites

  CONTENTS

  • 5.1 Introduction
  • 5.2 Phylum Platyhelminthes
  • 5.2.1 Trematoda
  • 5.3 Class Cestoda
  • 5.3.1 Order Pseudophyllidea/Diphyllobothridea
  • 5.3.2 Order Cyclophyllidea
  • 5.4 Phylum Acanthocephala

  5.1 Introduction

  In this chapter, we will introduce three of the most important groups of parasitic ‘worms’. Namely, the flatworms (flukes), the Tapeworms, and the thorny headed worms. The term ‘worm’ is, in a way, unfortunate because these organisms are only very distantly related to the real worms – the Annelida. Furthermore, most Annelida are free‐living although one group, the Hirudinea, includes the leeches, some of which feed on blood and some people consider these to be parasites. The thorny‐headed worms or acanthocephalans to give them their scientific name are unusual parasites. They are common parasites, but they rarely infect humans and domestic animals and therefore seldom gain attention in the scientific literature. They do, however, have some fascinating biological traits.

  5.2 Phylum Platyhelminthes

  Members of the phylum Platyhelminthes are commonly known as the ‘flatworms’ on the not unreasonable basis that they are dorsoventrally flattened and worm‐like in appearance. They are acoelomate soft‐bodied animals that are bilaterally symmetrical (i.e., their left side is the same as their right side) with an obvious head‐end. Most platyhelminths have a mouth at the anterior end although in some free‐living species the mouth is situated at or close to the centre of the body, while in Tapeworms the mouth is absent. Tapeworms also lack a gut although this is present in most other platyhelminth species and usually consists of a blind‐ending sack or series of branching tubules. The lack of an anus means that waste material is passed back through the mouth. Platyhelminths do, however, have a ramifying series of tubules that constitute their ‘excretory system’. Flame cells (protonephridia) maintain the movement of fluid within the excretory system, and the waste is removed through excretory pores. Because the excretory system removes excess water and ions, it is sometimes referred to as the osmoregulatory system. Most platyhelminths are hermaphrodites, containing both male and female reproductive organs, although in a few species there are separate male and female sexes.

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  Principles of Veterinary Parasitology

  • Dennis Jacobs, Mark Fox, Lynda Gibbons, Carlos Hermosilla(Authors)
  • 2015(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  CHAPTER 5 Platyhelminthes (‘flatworms’)

  1. 5.1 Introduction
  2. 5.2 Cestodes
     1. 5.2.1 Key concepts
  3. 5.3 Cyclophyllidean Tapeworms
     1. 5.3.1 Cyclophyllidean life-cycle
     2. 5.3.2 Metacestodes
     3. 5.3.3 Taenia
        1. Metacestodes
        2. Taenia species of humans
        3. Taenia species of dogs
        4. Taenia species of cats
     4. 5.3.4 Echinococcus
        1. Metacestodes
        2. Life-cycle
        3. Hydatid disease
     5. Epidemiology
        1. Alveolar hydatid disease
     6. 5.3.5 Other cyclophyllidean Tapeworms
        1. Metacestode
        2. Anoplocephala
        3. Moniezia
        4. Dipylidium
        5. Poultry cestodes
  4. 5.4 Pseudophyllidean Tapeworms
     1. 5.4.1 Pseudophyllidean life-cycle
     2. Avoid common mistakes!
     3. 5.4.2 Important pseudophyllideans
  5. 5.5 Cestocidal drugs
     1. 5.5.1 Praziquantel
  6. 5.6 Trematodes
     1. 5.6.1 Digenean trematodes
        1. Body structure
        2. Life-cycles
        3. Important digenean trematodes
     2. 5.6.2 Fasciola
        1. Preparasitic life-cycle
        2. Snail biology
        3. Parasitic migration
        4. Disease manifestations
        5. Pathogenesis of acute disease
        6. Pathogenesis of chronic disease
     3. 5.6.3 Other digenean trematodes
        1. Paramphistomum
        2. Dicrocoelium
        3. Fascioloides
        4. Schistosoma
        5. Trematodes of dogs and cats
  7. 5.7 Flukicidal drugs
     1. 5.7.1 Benzimidazoles
     2. 5.7.2 Salicylanilides

  5.1 Introduction

  Platyhelminths typically have a flattened body with suckers, or similar structures, for attachment to their host. Most are hermaphrodite (i.e. each individual has male and female sex organs). The body surface (‘tegument’) is metabolically active and therefore structurally and functionally distinct from the arthropod exoskeleton, the cuticle of nematodes or mammalian skin.

  The term platyhelminth (meaning ‘flatworm’) encompasses two major parasitic groups: the Cestoda (Tapeworms) and the Trematoda (flukes). Adult cestodes are segmented and ribbon-like, reminiscent of a tape-measure – hence the traditional name ‘tapeworm’ (see Figure 5.1 ). They have no alimentary tract and absorb nutrients through the tegument. In contrast, trematodes do have a mouth and internal digestive system. They are leaf-shaped and unsegmented (see Figure 5.2 ).

  Figure 5.1

  A typical tapeworm (Taenia saginata

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  Clinical Infectious Disease

  • David Schlossberg(Author)
  • 2015(Publication Date)
  • Cambridge University Press

    (Publisher)

  PART XXIV Specific organisms: parasites 195. Intestinal roundworms 1250 Kathryn N. Suh and Jay S. Keystone 196. Tissue nematodes 1258 Thomas A. Moore 197. Schistosomes and other trematodes 1268 James H. Maguire 198. Tapeworms (cestodes) 1274 Zbigniew S. Pawlowski 199. Toxoplasma 1279 Roderick Go and Benjamin J. Luft 200. Malaria 1285 Jessica K. Fairley and Henry M. Wu 201. Human babesiosis 1295 Tempe K. Chen, Choukri Ben Mamoun, and Peter J. Krause 202. Trypanosomiases and leishmaniases 1302 Anasta´cio de Queiroz Sousa, Selma M. B. Jeronimo, and Richard D. Pearson 203. Intestinal protozoa 1313 Paul Kelly 204. Extraintestinal amebic infection 1318 Robert Huang and Sharon L. Reed 195. Intestinal roundworms Kathryn N. Suh and Jay S. Keystone Nematodes (roundworms) are the most common parasites infecting humans worldwide. Of almost half a million species of roundworms, approxi- mately 60 are known to be pathogenic to humans. Among the most prevalent human infections are those due to the intestinal (lumen-dwelling) nematodes. Ascaris lumbricoides and Trichuris tri- chiura each infect over 1 billion people worldwide; hookworms (Ancylostoma duodenale and Necator americanus) infect almost the same number. Other important nematodes of humans include Strongyloides stercoralis and Enterobius ver- micularis. Coinfection, in particular with A. lum- bricoides and T. trichiura, is common. Ascaris lumbricoides, hookworm, and T. tri- chiura, collectively referred to as geohelminths (or soil-transmitted helminths), share the require- ment for eggs or larvae to mature in soil in order to be infective to humans. Due to this obligate soil stage of maturation, these parasites cannot be transmitted from person to person. In contrast, S. stercoralis is able to complete its entire life cycle within the human host, and like E. vermicularis, both person-to-person transmission and autoin- fection can occur.

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  Diseases and Parasites of Cattle

  • Hambidge, Gove(Authors)
  • 2021(Publication Date)
  • Biotech

    (Publisher)

  Chapter 12 Tapeworm and Roundworm Parasites of Cattle Dale A. Porter 1 1 Dale A. Porter is Associate Parasitologist, Regional Animal Disease Research Laboratory, Auburn, Ala., Bureau of Animal Industry. Seventy or more species of Tapeworms and roundworms infest cattle, some causing serious losses. Here are facts about the more important, including methods of prevention and treatment. The article on worm parasites of sheep should also be read by those interested, practically and scientifically, in cattle worms. Tapeworm and roundworm parasites reported to affect cattle throughout the world comprise over 70 different species. Although some species occur infrequently and others are comparatively harmless to their bovine hosts, some exact a heavy annual toll from the beef dairy industries. Losses are due to deaths from gross parasitism, lowered vitality and resultant poor growth and performance and condemnation, in the course of meat inspection, of carcasses or edible parts as a result of invasion by parasites. Members of these two groups of parasites–Tapeworms and roundworms– vary considerably in their location, structure and harmfulness. The cestodes or Tapeworms, of cattle are found as adults in the intestine and as larval forms in the muscles, liver, lungs and other viscera. The adults are elongated, flattened worms consisting of a head and a chain of segments, each having both male and female reproductive organs and terminal segments containing mature eggs. The larval forms, commonly referred to as bladder worms because they resemble a bladder in shape, are intermediate asexual This ebook is exclusively for this university only. Cannot be resold/distributed. stages of Tapeworms that live as adults in the intestines of man and other animals. The bladder worms vary in diameter from one-fourth inch in the case of the beef bladder worm ( Cysticercus bovis ) to as much as 6 inches in the case of the hydatid cysts ( Echinococcus granulosus ).

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  Foundations of Wildlife Diseases

  • Richard G. Botzler, Richard N. Brown(Authors)
  • 2014(Publication Date)
  • University of California Press

    (Publisher)

  85 FOUR Flatworms trematodes and cestodes CONTENTS Introduction to Phylum Platyhelminthes 85 Trematodes (Flukes) 86 Digenetic Trematodes 86 Liver Trematodes 90 Fascioloides magna 90 Dicrocoelium dendriticum 93 Intestinal Trematodes 96 Sphaeridiotrema globulus and S. pseudoglobulus 96 Ribeiroia ondatrae 97 Blood Flukes (Schistosomes) 101 Cestodes 102 Cyclophyllidean Cestodes: Mammals 102 Life Cycles Using a Cysticercus 107 Life Cycles Using a Coenurus 108 Taenia (Multiceps) multiceps 10 8 Life Cycles Involving Hydatid Cysts 109 Echinococcus multilocularis 110 Other Echinococcus spp. 112 Cyclophyllidea: Avian Cestodes 113 Literature Cited 113 INTRODUCTION TO PHYLUM PLATYHELMINTHES Platyhelminths ( platy: f lat, helminth: worm) are a phylum of simple, soft-bodied, dorsoventrally flattened invertebrates with bilateral symmetry. While there is a blind gut in some, none have a body cavity (coelom); thus, platyhelminths are classified as acoe-lomates (Roberts and Janovy 2000). They are among the simplest animals to have a nervous system. Platyhelminths of interest for wildlife belong to the Class Cercomeridia (App. 1: Table 3). Two platyhelminth groups are of major importance in wildlife disease studies: trematodes (Subclass Trematoda), also called flukes, and cestodes (Infraclass Cestoidea), also called Tapeworms (Roberts and Janovy 2000) (App. 1: Table 3). Although there are many free-living platyhelminths, all trematodes and cestodes engage in parasitic life styles. 86 flatworms TREMATODES (FLUKES) Trematodes are characterized as having an oral sucker that includes a pharynx, and with a vari-ably placed ventral sucker (acetabulum) as a hold-fast organ (Roberts and Janovy 2000) (Fig. 4.1); a few trematodes have only one sucker, usually at the anterior end (Bush et al. 2001). While lacking coeloms, trematodes have well-developed meso-derms that form the parenchyma, reproductive organs, and musculature in the adult stages (Roberts and Janovy 2000).

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  The Flying Zoo

  Birds, Parasites, and the World They Share

  • Michael Stock(Author)
  • 2019(Publication Date)
  • University of Alberta Press

    (Publisher)

  11 Parasitic worms use other methods to get themselves into birds. These include weakening the stamina of their intermediate host, making their T H E F L Y I N G Z O O 126 host more conspicuous, and disorienting the host. 12 Unfortunately for some intermediate hosts, helminths can employ more than one of these methods at the same time. For example, small fish such as spottail shiners, fathead minnows, pearl dace, and sticklebacks can be infected by tapeworm larvae (called plerocercoids) of Ligula intestinalis and Schistocephalus solidus . Worms are found packed in the abdominal cavities of fish. They can grow to 8 cm in length, which may be as long as the body of the host, and can account for 50% to 80% of the host’s body weight. To put this in perspective, if you weigh 150 pounds (68 kg), then 75 to 120 pounds (34 to 54 kg) of your weight would be worm tissue. Various studies have found that fish infected with plerocercoids are sluggish in their movements and lag behind their schools. Infected fish cannot swim continuously, and they use more oxygen than uninfected schoolmates. They swim at the surface in shallow, warm water near the shore. 13 Most fish are counter-shaded, with dark colouring on top and white bellies on the bottom, so that they are concealed from predators above or below them. However, fish whose bellies are swollen with plerocercoids can easily be spotted from above, because their pronounced abdomens give the appearance of two white stripes. 14 In some lakes, I have been able to catch infected fish by hand, and have had the unpleasant experience of having the tapeworm larvae burst out of the unfortunate fish’s thin abdominal wall, right into my hand. As you may have guessed by now, the definitive hosts of these tape-worms are various types of fish-eating birds, such as kingfishers, loons, grebes, gulls, and cormorants.

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  Applied and Economic Zoology

  • Rathoure, Ashok Kumar(Authors)
  • 2021(Publication Date)
  • Daya Publishing House

    (Publisher)

  As a group, parasites have little need for sense organs and seldom have them as highly developed as do related free living animals. Fixed parasites do not need and do not have, well developed organs of locomotion, if they possess any. Intestinal parasites do not need highly organized digestive tracts and the Tapeworms and spiny headed worms have lost this portion of their anatomy completely. On the other hand, parasites must be specialized, often to a very high degree, to adhere to or to make their way about in their particular host or the particular part of the host in which they find suitable conditions for existence. Every structure, every function, every This ebook is exclusively for this university only. Cannot be resold/distributed. instinct of many of these parasites is modified, to a certain extent, for the sole purpose of reproduction. A fluke does not eat to live, it eats only to reproduce. The inevitable death of the host is the parasite’s doomsday, against which it must prepare by producing all the offspring possible, in the hope that enough will survive to keep the race from extinction. The complexity to which the development of the reproductive systems may go is almost incredible. In some adult Tapeworms not only does every segment bear complete male and female reproductive systems, but it also bears two sets of each. The number of eggs produced by many parasitic worms may run well into the millions. The complexity of the life history is no less remarkable. Not only are free living stages interposed and intermediate hosts made to serve as transmitting agents, but also often asexual multiplications are passed through during the course of these remarkable experiences. Mutual Tolerance of Hosts and Parasites: The effect of parasitism is felt by both parasite and host. A sort of mutual adaptation between the two is developed in proportion to the time that the relationship of host and parasite has existed.

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  Practical Guide to Diagnostic Parasitology

  • Lynne Shore Garcia(Author)
  • 2021(Publication Date)
  • ASM Press

    (Publisher)

  (Bottom row) Diagram of both a cysticercoid and adult worm in the small intestine (illustration by Sharon Belkin); Tribolium sp. flour beetle, which can be found in stored grains, cereals, etc. (courtesy Peggy Greb, USDA Agricultural Research Service, Bugwood.org). CESTODES: Intestinal 437 438 SECTION 7 CESTODES • Intestinal Hymenolepis diminuta Pathogenic Yes Disease Rat tapeworm disease Acquired Ingestion of immature tapeworm larvae (cysticercoid) from infected arthropods Body site Intestine Symptoms Vague to none Clinical specimen Stool Epidemiology Worldwide Control Improved hygiene, adequate disposal of fecal waste, adequate washing of contaminated fruits and vegetables LIFE CYCLE Rats, mice, humans (Adult worms in intestine) Eggs in feces Cysticercoid larvae in arthropods Ingestion of larvae (in arthropods) Diagnosis Although Hymenolepis diminuta is commonly found in rats and mice, it is infrequently found in humans. It has a worldwide distribution in normal hosts, and fewer than 500 human cases, primarily from India, the former Soviet Union, Japan, Italy, and certain areas of the southern United States (Tennessee, Georgia, and Texas), have been reported. The adult worms or proglottids usually disin- tegrate in the gut; therefore, diagnosis is based on recovery and identification of the characteristic eggs. They are most easily identified in fresh speci- mens or those preserved in formalin-based fixatives. Morphologic characteristics of eggs in specimens in preservatives containing PVA are not as well delin- eated as those in formalin-fixed specimens. The standard O&P exam is recommended for recovery and identification of H. diminuta eggs in stool specimens, primarily from the wet- preparation examination of the concentration sediment. The eggs are most easily seen on a direct wet smear or a wet preparation of the concentration sediment. Diagnostic Tips In proficiency testing specimens, the eggs may not always have hooklets visible within the onco- sphere.

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