绦概带曼cestdesppt课件

1、Cestode parasites (Tapeworms)Medical Parasitology CourseDepartment of Pathogen BiologyShantou University Medical CollegeJin Liqun金 立 群May 2019Cestodes Platyhelminthes (the flatworms): Class Trematoda (The flukes or trematodes)Class Cestoda (The tapeworms or Cestodes)Characteristics:1 Adu

2、lt lives in the intestine of vertebrates.2 One or two intermediate hosts.3 Humans may serve as final host or intermediate host (Transport host or Paratenic host)4 Hermaphroditic.5 The nutrition of tapeworms is through integument (skin) as they lack digestive tract. Tegument Cestodes They have sucker

3、s or sucking grooves and teeth that grasp the host (Holdfast organs) Behind a short neck are repeated parts of the worm, each containing reproductive structures with eggs and /perit/biology_image_gallery1.htmStrobila 1 Tiny scolex 2 Strobila which makes up most of the “worm” 3 T

4、he strobila consists of a linear series of proglottids 4 Each mature proglottid carries a set of female and male reproductive organsClassification of cestodesPhylum Platyhelminthes (flatworm) Class Cestoda Two important orders: Order Pseudophyllidea : Spirometra mansoni Diphyllobothrium latum( fish

5、tapeworm) Order Cyclophyllidea : Teania solium (pork tapeworm) Teania saginata (beef tapeworm) Echinococcus granulosus (hydatid worm)The scolex is the part of the worm that anchors it to the intestinal epithelium and prevents that the worm is passed with the digested food.Morphology of tapeworms: Th

6、e scolexDifferent types of scolicesSome cestodes carry a rostellum which is armed with hooks.Muscular holdfast organs include suckers or acetabula (usually 4 per scolex), weakly muscled grooves (bothria, 2 per scolex).Scolex of Taenia Solium Strobilation Strobilation: asexual process of forming segm

7、ents New proglottids are continuously formed in the neck just below the scolex (A) Along the length of the worm the proglottids increase in size and maturity, developing from premature (B) to mature (C) to the “gravid” stage (D) in which essentially the entire proglottid is filled with the uterus an

8、d eggs.The reproductive systemThe female includes a vagina from the genital pore to a seminal receptacle; an ovary; a single oviduct, the ootype, the duct from the seminal receptacle. The uterus leads from the ootype and may have either an opening or uteropore or end blindly. Proglottids without ute

9、ropores detach when gravid.The egg is formed in the ootype with the contributions from the ovary and the vitellaria.The male system consists of numerous testes, vasa efferentia from each testis to the sperm duct. The cirrus is surrounded by the cirrus pouch. Most often the cirrus pouch and female va

10、gina enter a common chamber, the genital atrium, and share a common opening, the genital pore.Developmental stagesWith very few exceptions vertebrates are the final host harboring the adult tape wormsMany invertebrates and vertebrates are parasitized as intermediate hostsThe embryonate egg contains

11、the oncosphere a larva that will penetrate the intestinal wall after eggs are swallowed by intermediate host The oncospheres of eucestoda have three pairs of hooks which makes it easy to identify themDiagram of oncosphere of Hymenolepis diminuta, dorsal viewTaeniid eggs. The eggs of Taenia saginata

12、and T. solium are indistinguishable morphologically. The eggs are rounded, 31 to 43 m, with a thick radially striated brown shell. Inside each shell is an embryonated oncosphere with 6 hooks. CDCDevelopmental stages (metacestodes) Pseudophyllidean cestodes procercoid: in the 1st Intermediate host.(a

13、t an end there is a cercomere=tail with 6 hooklets) plerocercoid :The larvae look fairly similar to the adult In the second host Cyclophyllidean The medically important larvae are cysticercoid, cysticercus and hydatid (some of these larvae provided amplification （ （Coenurus=many scolices)(D. latum)(

14、D. latum)(T. solium)(E. granulosus)(Hymenolepis sp.)Differentiation of the two orders (tapeworms) Pseudophyllidea CyclophyllideaScolex & holdfast 2 sucking grooves 4 suckersUterus curved ducts sack-like, without with opening openingVitelline gland follicle-like, anterior masses, to ovary posteri

15、or to ovaryIntermediate host 2 1Egg elliptic, thin shell, spherical, thick an operculum, an egg embryophore, cell and many yolk cells an oncosphereMorphology of adult tapewormAdult consists of segments (proglottids) 1 Scolex (head)2 Neck (the region of segment proliferation)3 Strobila ( A chain of s

16、egments behind the neck) Immature segments Mature segments Gravid segments Scolex/neck/ immature proglotid Anterior region of showing the scolex and neck region. The proglottids on the right are immature; note that the reproductive organs are just beginning to differentiate.Mature proglotidsMature p

17、roglottids of Taenia sp. each proglottid measures about 4 mm in length Mature proglottidgenital organsGravid proglottid:only the uterusexists in the segmentDifferences between Pseudophylidea and Cyclophylidea _Diferentiating Pseudophylidea Cyclophylidea Feature_Scolex two grooves four suckers (bothr

18、ium) Pseudophyllidea Cyclophyllidea Uterus curved ducts sack-like with a pore uterus pore is absentDifferences between Pseudophylidea and CyclophylideaEgg operculum without operculum an egg cell oncosphere and some (larva) yolk cellsMetacestode The developing stages in the intermediatehost are calle

19、d metacestode. such as: sparganum ( plerocercoid) cysticercus (bladder worm) hydatid cyst procercoidClinical aspectsDamage caused by adult: The majority of cases are symptomless. In somepatients may be intestinal discomfort, vomiting ordiarrhea. Appendicitis and intestinal obstruction may occur inso

20、me patients.Damage caused by larvae: The larval stages of tapeworms may produce serious diseases. Such as: hydatid disease Cysticercosis Sparganosis Summarized Life cycle of tapewormAdult egg hexacanth embryo (oncosphere) Metacestodes (larval stages) (1 or 2 intermediate hosts)Spirometra mansoni and

21、 sparganosisAdult tapewormScolexNeckImmature segmentsMature segmentsGravid segments*HermaphroditicMorphology of the adult worm Scolex: 1 to 2 mm long, with 2 sucking grooves.Mature segment Male genital system:Testis, vas efferens,vas deferens,seminal vesicle,Cirrus. Female genitalSystem: Ovary, ovid

22、uct,Ootype, uterus (with an opening)vaginayolk gland.* Gravid segment is similar to mature segmentEgg 52 to 76m by 31 to 44m,elliptic, brownish with an operculum (eyelid-like), one egg cell and some yolk cells inside. Sparganum The second-stage larva is called sparganum. It is elongated and tape-lik

23、e, milky white in color, and un-segmented. Question 1 Which kinds of hosts may human serve as in the life cycle of Spirometra mansoni ? Why/why not? A first intermediate host B second intermediate host C final host D transport hostQuestion 2 How many intermediate hosts are there in the life cycle of

24、 Spiromrtra mansoni ? What are they?Life cycleFirst intermediate host( copepod )The first intermediate host (copepod )and development of the larva egg (in water) Coracidium (larva) eaten by copepod and develop to procercoid (larva)The second intermediate host Procercoid (in copepod) eaten by tadepol

25、e and develop to sparganum (in Frog) 2nd intermediate host(frogs and sometimes snakes )Transport host: Amphibians, reptiles, and mammals. Adult Egg hatch in water Coracidium( intestine of final host) ingested by copepod 1st intermediate host swallowed by tadpole Sparganum (in frogs mucles) procercoi

26、d amphibians, reptiles, and mammals as 2nd intermediate host or transport host by pasting or eating sparganosisSparganosisLife cycle Adult Egg Coracidium copepod 1st intermediate host amphibians, reptiles or mammals 2nd intermediate host or transport host Sparganum procercoid Human are infected with

27、 sparganosis inthree ways:1 drinking fresh water containing infected copepod.2 applying the flesh (esp. frog or snake) as poultice on the eye or wound.3 eating raw or undercooked meat ( mammals, reptiles and amphibians, etc.)Questions How many intermediate hosts are there in the life cycle of Spirom

28、rtra mansoni ? What are they?Life cycle The first intermediate hosts are a large number of copepod crustaceans. The second intermediate hosts are frogs and sometimes snakes. (Amphibians, reptiles, and mammals and even human may serve as paratenic hosts) The final hosts are domestic and wild carnivor

29、es. Pathology of sparganosis 1 Humans can be infected by ingesting infected first intermediate hosts (e.g., infected copepods in drinking water) 2 ingesting infected second intermediate hosts (e.g., raw or undercooked amphibians, reptiles or mammals). 3 Humans may infected by pasting the eye or woun

30、d with flesh of frogs or other transport hosts. Sparganosis has been reported from many countries of the world, but is most common in Asia. Clinical manifestations1 Ocular sparganosis2 subcutaneous sparganosis3 oral sparganosis4 cerebral sparganosis5 visceral sparganosisThe pathology associated with

31、 sparganosis depends on the number and size of spargana and the organs involved :Infections consisting of one or two spargana in the deep muscles might cause no overt symptoms and go undiagnosed. Infections in the eye can result in blindness, while infections of subdermal tissues can result in painf

32、ul lumps that might be misdiagnosed as cancer .Sparganum in the breast of a female patient A sparganum recovered from a lump in the breast of a female patient suspected of having breast cancer Sparganum in the same patient The entire sparganum recovered from the above patient. Diagnosis If the intac

33、t parasite extracted, it can be recognized by the head with the characteristic deep invagination.A histological section containing a sparganum. Note the intense host response around the metacestode. Treatment The treatment for sparganosis is surgical excision of the localized infections. Praziquante

34、l is also effective. Epidemiology Sparganosis has been reported from many countries of the world, but is most common in Asia. Epidemology Human infected with sparganosis in three ways: 1 drinking fresh water containing infected copepod. 2 applying the flesh (esp. frog or snake) as poultice on the ey

35、e or wound. 3 eating raw or undercooked meat ( mammals, reptiles and amphibians etc.)Breast sparganosis A sparganum recovered from a lump in the breast of a female patient suspected of having breast cancer . Spargnosis Another route of infection in Asia is from poultices prepared from frogs infected

36、 with spargana that are applied directly to ulcers, sores, and inflamed eyes.Ocular (Eye) spargnosis Cerebral spargnosis is characterized by seizures, paresthesia, hemiparesis, and similar CNS symptoms.Diphyllobothrium latumTAENIA SOLIUM The Lancet (2019) 361: 547 T. solium has a scolex (A) with fou

37、r suckers and a double crown of hooks, a narrow neck, and a large strobila (2-4 m) (B) consisting of several hundred proglottids. About 2 months after ingestion, proglottids begin to detach from the distal end and are excreted in the feces. Each segment contains 50-60,000 fertile eggs. The armed sco

38、lex of T. solium (note hooks on top of scolex). CDC Taenia solium (pork tapeworm) 1 The adult worm lives in the intestine of humans.2 The larvae ( Cysticercus cellulosae ，bladder worm) localize in pigs mainly.3 Cysticercus cellulosae can also infect humans causing cysticercosis. MorphologyAdult : 2-

39、4 m long, 700-1000 segments: Scolex Neck Immature segment Mature segment Gravid segment Morphology Scolex: 1mm in diameter, a rostellum armed with two circles of hooks. ( armed tapeworm) four suckers Neck: The region for proliferationrostellum suckerImmature segment note that the reproductive organs

40、 are just beginning to differentiate.(Carmine stained)Developing reproductive organsMature segments (proglottids)Hermaphroditic testes, sperm duct ovary, uterus genital pore vitellaria (yolk gland) excretory canal Mature segmentMature segment ( Ovary with 3 lobes) a small central lobe Note: Trilobed

41、 ovary ( Carmine stained )Gravid segmentNote : Less than 14 (7-13) lateral uterine branches (one side) India ink stained Cysticercus cellulosae ScolexcystThe cyst is filled with fluid Cysticercus cellulosae It is soybean-like in shape, has an small scolex invaginated into the translucent cyst. (left

42、) The scolex evaginated from the cyst (right)Cysticercius cellulosaeCystcercus cellulosae in muscles of pigs (measly pork ) Taenia saginata (beef tapeworm) 肥胖带绦虫，牛带绦虫肥胖带绦虫，牛带绦虫 4-8 m , 1000-2000 segments Scolex Neck Immature segment Mature segment Gravid segmentTAENIA SAGINATA Beef tapeworm Ranges i

43、n length from 4-8 m Geographic distribution: cosmopolitan. Most common where poor sanitation and no inspection of meat.Transmission: Ingestion of larval form in undercooked beefIn N. America 1 in 100 is infected. In third-world nations could be up to 10%No symptoms or some abdominal discomfortDiagno

44、sis: finding eggs or proglottids in fecesTaenia saginata adult worm. Taenia saginata, Scolex(Mit freundlicher Genehmigung Roche AG)Scolex and Neck 1.5- 2 mm in diameter Without hooks or undistinguished rostellum Four suckers ( unarmed tapeworm)Mature segment (ovary with 2 lobes) Note : Bilobed ovary

45、 (Carmine stained)Gravid segment India ink technique Note : More than 15 lateral uterine branches (one side). Cysticercius bovis （牛囊尾蚴）（牛囊尾蚴） Show invaginated scolex (left) show evaginated scolex (right) The scolex is similar to that of adult worm in morphologyCysticercius bovisCysticercus bovis Cys

46、ticercus bovis showing the bladder and the scolex (measly beef)Taenia eggs （ （带绦带绦虫卵）虫卵） The eggs of Taenia saginata and T. solium are indistinguishable morphologically . Taenia egg spherical 31 to 43 m a thick embryophore an oncosphere inside an egg shell outside (usually break away from the eggs i

47、n the feces)Gravid segment ( the primary lateral branches of the uterus) Taenia solium Taenia saginata The uterus The uterus has 7 to 13 has 15 to 30 lateral branches lateral branches on each side on each sideLife cycle of Taenia solium Humans serve as final hosts as well as intermediate hosts in th

48、e life cycle of Taenia solium. ( both adult and bladder worm parasite in humans) 1 The adult worm lives in the small intestine of humans( pork tapeworm infection) 2 The larvae (Cysticercus cellulosea, bladder worm ) localize and develop in pigs (intermediate host) 3 The cysticercus cellulosae may al

49、so infect humans causing cystcercosis (humans as intermediate hosts) Life cycle of Taenia saginataThe life cycle of Taenia saginata is similar to that of Taenia solium, but the intermediatehost is cattle.The custicercus bovis (the beef bladder worm ) nearly does not parasite in human body.Humans ser

50、ve as the final hosts only.(beef worm infection)Life cycle of Taenia saginata and Taenia solium Humans are the only definitive hosts for Taenia saginata and Taenia solium.Eggs or gravid proglottids are passed with feces The eggs can survive for days to months in the environment. Cattle (T. saginata)

51、 and pigs (T. solium) become infected by ingesting eggs or gravid proglottids In the animals intestine, the oncospheres hatch , invade the intestinal wall, and migrate to tissues, where they develop into cysticerci. Humans become infected by ingesting raw or undercooked infected meat . In the human

52、intestine, the cysticercus develops over 2 months into an adult tapeworm. The adult tapeworms attach to the small intestine by their scolices and reside in the small intestine The adults produce gravid proglottids which detach from the tapeworm, and migrate to the anus or are passed in the stool.Lif

53、e cycle Summary of life cycleCysticercus cellulosae oncosphere(tissues and organs) (eggs of T.solium)Adult gravid proglottids(Human s intestine) or eggs Measly pork ingested by pig by human (T.solium) Measly beef ingested by cattle by human (T.saginata) Cysticercus cellulosae oncosphere (in measly p

54、ork ) penetrate intestinal wallCysticercus bovis into circulatory system, (in measly beef ) then to different tissues. (muscles and viscera)Geographic DistributionBoth species are worldwide in distribution. Taenia solium is more prevalent in poorer communities where humans live in close contact with

55、 pigs and eat undercooked pork, and in very rare in Muslim countries.Clinical FeaturesTaenia saginata taeniasis produces mild abdominal symptoms and may causemalnutrition. (Epigastric pain, vomiting, diarrhea) The most striking feature consists of the passage (active and passive) of proglottids.The

56、patients may find gravid proglottids themselves and take the segments to see doctors. Occasionally, appendicitis or cholangitis can result from migrating proglottids. Taenia solium taeniasis is less symptomatic than Taenia saginata taeniasis. The main symptom is often the passage (passive) of proglo

57、ttids. The most important feature of Taenia solium taeniasis is the risk of development of cysticercosis. Laboratory Diagnosis Microscopic identification of eggs and proglottids in feces is diagnostic for taeniasis. Repeated examination and concentration techniques will increase the likelihood of de

58、tecting light infections. Species determination of Taenia is impossible if solely based on microscopic examination of eggs, because all Taenia species produce eggs that are morphologically identical. Eggs of Taenia sp. are also indistinguishable from those produced by cestodes of the genus Echinococ

59、cus. Microscopic identification of gravid proglottids (or, more rarely, examination of the scolex) allows species determination. TAKE EXTREME CARE IN PROCESSING THE SAMPLES! INGESTION OF EGGS CAN RESULT IN CYSTICERCOSIS! The prognosis for intestinal taeniasis is good, but the infection should be ter

60、minated to reduce the risk of cysticercosis!Diagnostic findings Microscopy: 1 egg * The eggs can not be used as species identification. 2 scolex Differential Morphology of the Diagnostic stages of the two species: gravid segment Species(Gravid segment)SizeAppearance of UterusOtherTaenia solium12 mm in