Phylum Platyhelminthes. Class Trematoda. Class Cestoda. Phylum Nemathelminthes

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Phylum Platyhelminthes. Class Trematoda. Class
Cestoda. Phylum Nemathelminthes

• By Pryvrotska I.B.

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• According to the way of development parasites are
  classificated into biohelminthes and
  geohelminthes.
• Geohelminthes develop without intermediate
  hosts.
• Biohelminthes have complete life cycle with
  intermediate hosts.
• The flatwotms consists of some 12, 200 species,
  including classes of parasitic worms Trematoda,
  Cestoda

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General characteristic of Flatworms

• All flatworms are acoelomate, triploblastic, and
  bilaterally symmetrical.
• flattened dorsoventrally
• they have a definite head at the anterior end.
• The most of flatworm species, in all three
  classes, are hermaphrodites. A single individual
  generally cannot fertilize itself, although
  exceptions do exist.

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General characteristic of Class Trematoda

•   - Flattened dorsoventrally (leaf-like).
•   - Unsegmented.
• - Body is covered by cuticle.
• - Organs of fixation oral sucker, ventral
  sucker.
• - Genital system Trematodes are hermaphrodites
  except genus Schistosoma.
•  -The life cycle is passed in two hosts
  (alternation of hosts)

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BLOOD FLUKES - genus SCHISTOSOMA

• Distribution Africa, Asia, Middle East, Latin
  America.
• Schistosoma mansoni and Schistosoma japonicum
  cause Hepatosplenic Schistosomiasis.
• Schistosoma haematobium causes Urinary
  Schistosomiasis.
• Localization venous vessels of bowel, liver,
  and bladder.
• Morphology atypical trematodes which the adult
  female nesting within a specialized groove in the
  body of the larger male.

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BLOOD FLUKES

• Transmission infection through skin of larvae
  from snail hosts.
• Infective stage cercariae.
• Intermediate host snail.
• Definitive host man.
• Mode of transmission penetration of skin by
  cercarie.

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BLOOD FLUKES

• Clinical manifestations of Hepatosplenic
  Shistosomiasis
• eosinophilia,
• granulomatous polyps in colon,
• Fever,
• anorexia, weight loss,
• anemia,
• portal hypertension,
• dysentery and cirrhosis of liver,
• pruritic skin rash.
• Eggs go back through portal circulation to liver,
  causing hepatomegaly, liver tenderness.

• Clinical manifestations of Urinary
  Schistosomiasis
• eosinophilia,
• hematuria,
• terminal dysuria (pain, difficulty at the end of
  urination)
• obstructed urine flow.

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Laboratory diagnostics and Prevention

• Hepatosplenic Schistosomiasis eggs with lateral
  spine in feces.
• Laboratory diagnostics of Urinary
  Schistosomiasis eggs with terminal spine in
  urine
• Prevention involves proper disposal of human
  waste and eradication of the snail host when
  possible.
• Swimming in endemic areas should be avoided.

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LUNG FLUKE PARAGONIMUS WESTERMANI an agent of
paragonimiasis

• Distribution Far East, Central America, Africa,
  and India.
• Morphology an egg-like form of the body, from
  7,5 to 16 mm.

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LUNG FLUKE

• Mode of transmission ingestion of metacercarial
  cysts in crabs or crayfish.
• Final hosts carnivorous mammals, pigs, humans.
• Intermediate hosts
• 1) snail (sporocyst, redia, cercaria)
• 2) crabs or crayfish (metacercaria).
• Infective stage metacercariae

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LUNG FLUKE

• Clinical disease a chronic cough with bloody
  sputum, dyspnea, pleuritic chest pain, and
  pneumonia.
• Laboratory diagnosis eggs in sputum or feces.
• Prevention cooking crabs and crayfish properly.

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BILIARY (LIVER) FLUKES FASCIOLA HEPATICA an
agent of fascioliasis.

• Distribution endemic in Far East.
• Localization bile ducts, gallbladder, and
  pancreas.
• Morphology large size (3-5 cm) and conical form
  of the body
• sucking disks (oral and abdominal)
• Multibranched uterus is situated under the
  abdominal sucking disk.
• Testis are branched too and located in the middle
  part of the body.

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FASCIOLA HEPATICA

• Life-cycle
• Final host - herbivorous mammals (horses) and
  humans.
• Intermediate host the snail Limnea truncatula.
• Transmission fecal-oral
• Invasive stage adolescariae.

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FASCIOLA HEPATICA

• Clinical disease Parasites obstruct bile ducts
  and lay eggs within them, leading to
  cholelithiasis (gallstones).
• Biliary obstruction can occur, sometimes causing
  biliary cirrhosis.
• Diagnosis immature eggs in feces.
• Prevention involves not eating wild aquatic
  vegetables.

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OPISTHORCHIS FELINEUS

• Opisthorchiasis.
• Distribution Siberia.
• Morphology
• flat, the length of the body 4-13 mm.
• In the middle part of the body there is a
  branched uterus.
• Behind it there is a round ovary.
• roseolla-like testis in the back of the uterus -
  a diagnostic sign of this worm.

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OPISTHORCHIS FELINEUS

• Life-cycle
• Final host - carnivorous mammals and humans.
• Intermediate host
• 1) - snail Bithynia leachi genus
• 2) - fish.
• Transmission ingestion of fish, which contains
  metacercariae.
• Invasive stage metacercariae cysts in fish
  muscles.
• Localization bile ducts, gallbladder, liver.

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OPISTHORCHIS FELINEUS

• Clinical disease
• cholecystitis and cholelithiasis,
• hepatic colic, cirhosis.
• Infection can lay dormant for several years
  before presenting clinically.
• Diagnosis immature eggs in feces, in fluid from
  biliary drainage, or duodenal aspirate.
• Prevention involves not eating undercooked or
  contaminated raw, frozen, dried, pickled, and
  salted fish eradication of snail hosts when
  possible.

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DICROCOELIUM LANCEATUM causes Dicrocoeliasis.

• Distribution worldwide.
• Localization bile ducts, gallbladder and liver
  of mammals (cattle, horses). Very rare in
  humans.
• Morphology the worms are 1 cm long with
  lanceolate form of the body
• Two round testis are situated in the front of the
  body - the diagnostic sign of this worm.
• Transmission ingestion of plants with the ants,
  which contain metacercariae.

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DICROCOELIUM LANCEATUM

• Invasive stage metacercariae.
• Life-cycle
• Final host - herbivorous mammals (cattle,
  horses).
• intermediate host
• 1- the snail of Zebrina and Helicela genus,
• 2- the ants Fornica genus.
• Clinical disease is similar to fascioliasis.
• Diagnosis immature eggs in feces.
• Prophylactics eradication of the snails, ants
  when possible dehelmithization of cattle.

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Tapeworms (Cestoda)

• scolex, strobila or chain of proglottids
  (multiple segments) of varying stages of
  maturity.
• They have no digestive tract
• The cestodes receive all of its nutrients be the
  tegument.
• The scolex has specialized means of attaching to
  the intestinal wall, namely suckers, hooks, or
  sucking grooves.
• All cestodes have stage of larva and stage of
  oncosphere in the life cycle.

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Taenia solium

• The adult T. solium -taeniasis solium.
• T. solium larvae cause cysticercosis.
• Distribution Teniasis and cysticercosis occur
  worldwide .
• Morphology
• scolex with 4 suckers and circle of hooks
• gravid proglottids, which have 7-12 primary
  uterine branches.
• Larva of T.solium called cysticercus.
• A cysticercus consist of a pea-sized fluid-filled
  bladder with an invaginated scolex.

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Taenia solium

• Life cycle
• Transmittion fecal-oral
• Invasive stage cysticerci.
• Definitive hosts humans
• Intermediate hosts - pigs
• Humans can be infected by eating raw or
  undercooked pork containing the larvae
  cysticercus.

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Taenia solium

• The cysticerci can become large in eye,
  subcutaneous tissue, brain, lung, heart, and
  muscle. In the brain, they manifest as a
  space-occupying lesion.

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Taenia saginata

• taeniasis saginata. Distribution occur worldwide
• Morphology.
• scolex with 4 suckers without hooklets.
• proglottids have 17-35 primary uterine branches.
  Larva of T.saginata called cysticercus.
• Transmittion fecal-oral
• Invasive stage cysticerci

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• Life cycle.
• Definitive hosts -humans
• Intermediate hosts - cattle Humans can be
  infected by eating raw or undercooked beef
  containing larvae.
• Laboratory diagnosis gravid proglottids (with
  17-35 uterine branches) may be found in the
  stools.
• Prevention. Prevention of taeniasis saginata
  involves cooking beef adequately and preventing
  cattle from ingesting human feces by disposing of
  waste properly.

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• Clinical manifestation of teniasis saginata
• abdominal pain,
• nausea,
• diarrhea,
• weight loss,
• infection may by asymptomatic.
• In some, proglottids appear in the stools and
  may even protrude from the anus.

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Diphyllobothrium latum, the fish tapeworm, causes
diphyllobothriasis

• Distribution Scandinavia, northern Russia,
  Japan, Canada, USA.
• Morphology.
• scolex with 2 elongated sucking grooves.
• The proglottids are wider than they are long, and
  the gravid uterus is in the form of a rosette.
• Adult worm is the longest of the tapeworms, up to
  13 m.
• Larva called plerocercoid.

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• Transmittion fecal-oral.
• Invasive stage plerocercoid.
• Definitive hosts- humans .
• Intermediate hosts
• -1)copepod crustacea
• -2) freshwater fish
• Humans infected by eating raw or undercooked fish
  containing plerocercoids

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• Clinical disease little damage in the small
  intestine.
• megaloblastic anemia occurs as a result of
  vitamin B12 deficiency caused by preferential
  uptake of the vitamin by the worm.
• Most patients are asymptomatic, but abdominal
  discomfort and diarrhea can occur.
• Diagnosis depends on finding the typical eggs,
  oval, yellow-brown eggs with an operculum
  (lidlike opening) at one end, in the stools.
• Prevention involves adequate cooking of fish and
  proper disposal of human feces.

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Hymenolepis nana (dwarf tapeworm) is found
worldwide, commonly in the tropics.

• Morphology. It is only 2-3 cm in length. Scolex
  has round form and contain suckers and hooks.
• A neck is very long and thick. Strobila has 200
  proglottides.
• The uterus has an excretory ostium.
• Eggs are released from it into the feces.
• Transmission fecal-oral (by the ingestion of
  eggs from contaminated food or water).
• Invasive stage egg.

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• Life cycle.
• The eggs of H. nana are directly infectious for
  humans
• ingested eggs can develop into adult worms
  without an intermediate host.
• Within the duodenum, the eggs hatch and
  differentiate into cysticercoid larvae and then
  into adult worms.
• Gravid proglottids detach, disintegrate, and
  release fertilized eggs.
• The eggs either pass in the stool or can reinfect
  the small intestine (autoinfection). A lot of
  H.nana worms (sometimes hundreds) are found.

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• Clinical disease asymptomatic, but diarrhea and
  abdominal cramps may be present.
• Diagnosis can be proved by observing eggs in
  stool.
• Prevention consists of good personal hygiene and
  avoidance of fecal contamination of food and
  water.

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Echinococcus granulosus (dog tapeworm)

• Mediterranean region, the Middle East, and
  Australian, USA (western states).
• Morphology. Worm is up to 3-5 mm. Scolex has
  suckers and hooks. A neck is short. Strobila has
  3-5 proglottides. Posterior segment (mature) is
  the largest and contains uterus with the
  haustrums, genital pore situated in the back of
  the proglottid.

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• Transmission fecal-oral
• Invasive stage egg
• Life cycle.
• Definitive hosts dogs.
• Intermediate hosts sheep, humans.

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• Diagnosis made by Clinical manifestations.
  asymptomatic, but liver cysts may cause hepatic
  dysfunction. Cysts in the lungs can erode into a
  bronchus, causing bloody sputum, end cerebral
  cysts can cause headache and focal neurologic
  sings.
• Diagnosis made by routine X-ray, observation of
  eosinophilia, serologic tests.
• Prevention of human disease involves not feeding
  the entrails of slaughtered sheep to dogs.

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Echinococcus multilocularis

• Distribution is found in northern Europe,
  Siberia, Canada, the USA.
• - the definitive hosts are mainly foxes and the
  intermediate hosts are various rodents.
• Humans are infected by accidental ingestion of
  food contaminated with fox faeces.

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• The disease occurs primarily in hunters and
  trappers. Within the human liver, the larvae form
  multiloculated cysts with few protoscoleces,
  proliferate, producing a honeycomb effect of
  hundreds of small vesicles (without fluid).
• The clinical picture usually involves jaundice
  and weight loss. The prognosis is poor.

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Nematodes

• Roundworms with a cylindrical body and a complete
  digestive tract including mouth and anus.
• They are unsegmented, pseudocoelomate worms.
• The body is covered with a noncellular, highly
  resistant coating called a cuticle.
• Nematodes have separate sexes the female is
  usually larger than the male. The male typically
  has a coiled tail.
• The medically important nematodes can be divided
  into 2 categories intestinal and tissue
  nematodes.

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Ascaris lumbricoides

• causes ascariasis.
• Distribution worldwide.
• Morphology Adult worms are creamy or pink,
  spindle-shaped, covered by striated cuticle.
• Adult male about 20 cm in length, posterior end
  is curved ventrally
• Adult female about 25-40 cm in length, posterior
  end is straight.
• Eggs are brown, oval, covered by membranes. An
  external membrane is tuberous

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Ascaris lumbricoides

• Mode of transmission fecal-oral (alimentary).
  Humans are infected by eating eggs in soil
  contaminated with human feces.

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Ascaris lumbricoides

• Clinical manifestation
• - larvae may lead to pneumonia, eosinophilia.
• - Adults -intestinal obstruction, penetration of
  the intestinal wall, occlusion of the bile duct,
  the pancreatic duct or the appendix, toxic
  effects (nausea, vomiting). Most infections are
  asymptomatic.
• Laboratory diagnosis microscopic
  examination of faeces (eggs are oval with an
  irregular surface) larvae may be found in
  sputum.
• Prophylaxis
• washing hands before meals
• proper washing of vegetables eaten raw
• treatment of patients
• proper disposal of feces
• health education.

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Enterobius vermicularis

• causes enterobiasis.
• Distribution worldwide.
• Morphology Adult female worms are up to 10 mm
  in length, and male worms are up to 5 mm.
• Eggs are transparent and colourless,
  asymmetrical, with thin and smooth membrane,
  40-60 microm.

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Enterobius vermicularis

• Mode of transmission fecal-oral (alimentary).
• Infective stage eggs.
• The adult pinworms live in the large intestine
  approximately 30 days.
• After fertilization female worm migrates from
  the anus and releases thousands of fertilized
  eggs on perianal skin.
• Within 6 hours, eggs develop into larvae and
  become infectious.
• Reinfection can occur if they are carried to the
  mouth by fingers after scratching of the itching
  skin.

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Enterobius vermicularis

• Clinical manifestation Infection is frequent
  among children under 12 years of age. Perianal
  pruritus (itching) is most common symptom.
• Laboratory diagnosis the eggs are
  recovered from perianal skin by using the Scotch
  tape technique and can be observed
  microscopically (eggs are not found in the
  stools). Seldom adult worms can be found in the
  stools.
• Prophylaxis keep sanitary condition,
  treatment of patients

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Trichuris trichiuria

• causes trichocephaliasis (whipworm infection).
• Distribution worldwide, especially in the
  tropics.
• Morphology Adult female worms are up to 5,5 cm
  in length, and male are up to 4 cm. The anterior
  end of the body is hairlike.
• The eggs are brown, barrel-shaped with a plug at
  each end, 20-50 microm in size.

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Trichuris trichiuria

• Mode of transmission fecal-oral (alimentary).
• Infective stage eggs.

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Trichuris trichiuria

• Pathogenesis and clinical manifestation Adult
  worms burrow their hairlike anterior ends into
  the intestinal mucosa. They feed blood. Trichuris
  may cause diarrhea, abdominal pain, nausea, acute
  appendicitis. Most infections are asymptomatic.
• Laboratory diagnosis microscopic
  examination of feces (finding the typical eggs).
• Prophylaxis
• washing hands before meals
• proper washing of vegetables eaten raw
• treatment of patients
• proper disposal of feces health education.

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Trichinella spiralis

• causes trichinosis.
• Distribution worldwide, especially in eastern
  Europe and west Africa.
• Morphology
• 1) The adults female worms are up to 3-4 ? 0.6
  mm the adult male worms are up to 1.5 ? 0.04 mm
  
• 2) the incysted larvae (1 mm) is enclosed in a
  fibrous cyst wall.
• Localisation small intestine (adult worms) and
  striated muscles (larvae).
• Any mammal (rat, bear, fox) can be infected, but
  pigs are the most important reservoirs of human
  disease.

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Infective stage for humans larva.Mode of
transmission alimentary (eating raw or
undercooked meat, usually pork, containing larvae
encysted in the muscle).
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Trichinella spiralis

• Clinical manifestation
• initially diarrhea, abdominal pain followed by
  1-2 weeks later by fever, muscle pain,
• periorbital edema, and eosinophilia.
• Death, which is rare, is usually due to
  congestive heart failure or respiratory
  paralysis.
• Laboratory diagnosis muscle biopsy reveals
  larvae within striated muscle serologic test
  (become positive 3 weeks after infection).
• Prophylaxis
• by properly cooking pork and by feeding pigs only
  cooked garbage
• pork inspection in slaughter houses using a
  trichinoscope.

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Ancylostoma duodenale and Necator americanus
(hookworms)

• cause ancylostomiasis (hookworm infection).
  Morphology
• 1) Adult worms about 1 cm in length
• 2) Eggs are translucent, oval with blunt poles,
  40-60 microm in size
• 3) the rhabditiform larva is about 0.25-0.5
  microm with rhabditiform oesophagus (1/3 body
  length), pointed tail end
• 4) the filariform larva is about 0.6-0.7 microm
  with cylindrical oesophagus (1/4 body length),
  sharply pointed tail.

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Hookworms

• Hosts humans.
• Mode of transmission penetration of skin by
  filariform larva
• Infective stage filariform larva.
• Clinical manifestation
• 1) invasion stage (the larvae penetrate the
  skin) dermatitis and itching (ground itch)
• 2) migration stage pneumonia with eosinophilia
  
• 3) intestinal stage anemia, diarrhea, abdominal
  pain, nausea.

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Hookworms

• Laboratory diagnosis eggs in the stool blood in
  the feces is frequent finding.
• Prophylaxis disposing of sewage properly
  and wearing shoes.

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Thank you for attention!