Title: Phylum Platyhelminthes. Class Trematoda. Class Cestoda. Phylum Nemathelminthes
1Phylum Platyhelminthes. Class Trematoda. Class
Cestoda. Phylum Nemathelminthes
2- 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
3General 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.
4General 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)
5BLOOD 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.
6BLOOD 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.
7BLOOD 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.
8Laboratory 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.
9LUNG 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.
10LUNG 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
11LUNG 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.
12BILIARY (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.
13FASCIOLA HEPATICA
- Life-cycle
- Final host - herbivorous mammals (horses) and
humans. - Intermediate host the snail Limnea truncatula.
- Transmission fecal-oral
- Invasive stage adolescariae.
14FASCIOLA 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.
15OPISTHORCHIS 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.
16OPISTHORCHIS 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.
17OPISTHORCHIS 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.
18DICROCOELIUM 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.
19DICROCOELIUM 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.
20Tapeworms (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.
21Taenia 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.
22Taenia 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.
23Taenia 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.
24Taenia 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
25- 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. -
26- 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.
27Diphyllobothrium 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.
28- 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
29- 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.
30Hymenolepis 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.
31- 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.
32- 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.
33Echinococcus 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.
34- Transmission fecal-oral
- Invasive stage egg
- Life cycle.
- Definitive hosts dogs.
- Intermediate hosts sheep, humans.
35- 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.
36Echinococcus 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.
37- 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.
38Nematodes
- 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.
39Ascaris 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
40Ascaris lumbricoides
- Mode of transmission fecal-oral (alimentary).
Humans are infected by eating eggs in soil
contaminated with human feces.
41Ascaris 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.
42Enterobius 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.
43Enterobius 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.
44Enterobius 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
45Trichuris 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.
46Trichuris trichiuria
- Mode of transmission fecal-oral (alimentary).
- Infective stage eggs.
47Trichuris 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.
48Trichinella 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.
49Infective stage for humans larva.Mode of
transmission alimentary (eating raw or
undercooked meat, usually pork, containing larvae
encysted in the muscle).
50Trichinella 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.
51Ancylostoma 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. -
52Hookworms
- 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. -
53Hookworms
- Laboratory diagnosis eggs in the stool blood in
the feces is frequent finding. - Prophylaxis disposing of sewage properly
and wearing shoes.
54Thank you for attention!