6. GENERAL CHARACTER
• Segmented
• Dorsoventrally Compressed & Tape like.
• Size – mm – mtr. In length.
• Lake of mouth
• Live mucosa of small intestine.
• Class – cestoidea, order- Pseudophyllidea &
Cyclophyllidea.
8. Eggs
1. Pseudophyllidean – ovoid, operculated & not contain
embryo, 1st laid.
2. Cyclophyllidean – not operculated & two covering
(embryophore & egg-shell).
• Egg contains six hooked (hexacanth) embryo is called
onchophore. Does not have ciliated epithelium.
9. Life cycle
• Complete there life cycle in two different host, except H.
nana.
• Man is definitive host for most cestode, Except E.
granulosus.
• Majority of the cestode infection, only one intermediate
host is needed, except diphyllobothrium latum.
13. DIPHYLLOBOTHRIUM LATUM
• Common name: fish tape worm, broad tape worm.
• Source : fish
• Other spp. D.pacificum, D.cordatum, D.ursi,D.dentriticum.
Geographical distribution
• Endemic in Europe, Russia, japan, Tropica Africa, North &
south America.
14. Morphology
• Adult worm:- largest tapeworm.
• Length 10 mtr. With as many as
30k proglottids.
• Consists of Scolex, Neck and
Strobila.
15. Eggs
• Yellowish brown colour
• Oval, 70um in length & 45um breadth.
• Contains immature embryo.
• Operculated
• Not infective form
• Does not float in SS of common salt.
16. Larval stage
• The egg develops into 1st,2nd &3rd stage.
• 1st stage – coracidium ( from egg into
water)
• 2nd stage- procercoid
• 3rd stage –plerocercoid
17. Life cycle
• One definitive host (man)
• Two intermediate host
• 1st intermediate: small copepods
• 2nd intermediate: freshwater fish
18.
19.
20. Pathogenesis and Clinical features
• Most of D. latum infections are asymptomatic.
• Abdominal discomfort, diarrhea, vomiting, weakness and
weight loss or rarely intestinal obstruction, cholangitis
or cholecystitis.
• Vitamin B deficiency: The adult worm causes
dissociation of the vitamin B 12-intrinsic factor complex
within the gut lumen, and leads to development of
megaloblastic anemia
21. Laboratory diagnosis
• Stool Examination-
Characteristic eggs in the stool—
surrounded by egg shell and an
operculum at one end and a knob at
the other end.
• Eggs are bile-stained; do not float in
saturated salt solution.
• Proglottids may be discharged in the
stool in some cases.
22. Treatment
• Praziquantel is highly effective (drug of
choice).
• Niclosamide is given alternatively
• Parenteral vitamin B 12 to be given.
24. Taenia species
Classification
Taenia species pathogenic to humans-
– T.saginata (beef tapeworm)- intestinal taeniasis
– T.solium (pork tapeworm)- intestinal taeniasis and
cysticercosis
25.
26. Geographical distribution
• T. saginata has a worldwide distribution, whwre cattle
are raised & beef is eaten.
• T. solium is not widely distributed, mainly found in South
africa,china,india,Central America,Brazil & non islamic
country.
• 100 million people are infected with T.saginata & T.
solium.
27. Habitat
• Adult worms of both reside in small intestine ( upper
jejunum)
• Larva of T.Solium reside and cystic lesions in the
muscle, brain and eyes.
29. Eggs
• Round, 30-40 µm
• Covered by 2 layers
• Embryo/oncosphere
• Eggs of both Taenia spp. similar
• Bile stained
• Does not float in SS of common salt
30. Larvae- Cysticercus
• Taenia saginata -Cysticercus
bovis
• Found in cattle’s muscles, not
in man
• Taenia solium -Cysticercus
cellulosae
• Present in pig’s muscle &
also in Man
31. Life cycle of T.saginata
• Host:
– Definitive- Man
– Intermediate-cattle
• Infective stage:
– Cysticercus bovis (Man)
– Eggs (Cattle)
• Human Cycle
• Cattle cycle
33. Life cycle of T.solium
• Depends on the disease
• 1. Intestinal taeniasis
• 2.Cysticercosis
Host: man is definitive & cattle or pig is
intermediate
Mode of transmission:
Infective stage:
35. Cysticercus bovis/cellulosae
Small (6-9mm), round, grayish white
bladder like worm containing
invaginated scolex without hooklets
0.5-1.5cm, spherical, yellowish white
• Outer bladder like sac filled with
vesicular fluid
• Inner chamber contains growing
scolex with hooklets.
36. Pathogenesis and C/F
Intestinal taeniasis
– Asymptomatic /passage of proglottids in their feces
– Mild abdominal discomfort, loss of appetite, change in bowel
habit
– Occ. Obstruction by migrating proglottids- appendicitis or
cholangitis
Cysticercosis
C/F depends on cyst location
– Subcuatneous cysticercosis-palpable nodules
– Muscular cysticercosis-muscle pain, weakness
– Ocular cycticercosis-proptosis, diplopia, loss of vision
– Neurocysticercosis
37. Neurocysticercosis (NCC)
Most common form (60–90% cases) of cysticercosis, parasitic CNS
infection of man and adult onset epilepsy throughout the world
NCC is of two types:
1. Parenchymal: Involves brain parenchyma
2. Extraparenchymal sites are meninges, ventricles and spinal cord
Subarachnoid space (most common site), brain parenchyma.
It can be asymptomatic NCC to various Manifestations: Seizure (70% of cases),
Hydrocephalus, Increased intracranial pressure, Chronic meningitis, Focal
neurological deficits, Psychological disorders and dementia
38. Clinical presentation
• is variable and depends on number, location & size of
the cyst, the morphological stage of the cyst and the host
immune response.
39. Epidemiology of cysticercosis in India
• NCC is most common parasitic CNS infection of man
• Most common cause of adult onset epilepsy
• Recent studies [with the help of CT and MRI] suggested
the disease burden in India is 18% to 31% of suspected
cases of epilepsy.
• It appears to be more prevalent in various places like
Bangalore (NIMHANS), Delhi, Vellore, Bihar, Uttar
Pradesh, Pondicherry and Chandigarh.
41. b) Taenia specific antigen detection in stool (coproantigen) by ELISA
• Advantages:
– More sensitive than stool examination and Can detect carriers
• Limitation: It cannot differentiate between T.saginata and T. solium.
c) Antibody detection in serum
•Precipitation, agglutination, CFT and ELISA
•Limitation: Cannot differentiate b/w present & past infection
•Newer advances- Recently, Immunoblot is developed for T. solium specific
antibodies and claims 95% sensitive and 100% specific.
d)Molecular methods: DNA probe and PCR
42. • 2)Cysticercosis
a) Radio diagnosis (Imaging methods)
• CT or MRI scan- detect hypodense area (cysticerci) and
Hyperdense eccentric area inside the vesicle (scolex)
43. Antigen detection
• ELISA -using monoclonal T.
solium antibodies.
Histopathology
• Cysticerci can be detected in
muscles, eyes, subcutaneous
tissues by biopsy following
surgical removal or FNAC of the
cyst followed by microscopic
demonstration of the parasite.
Cysticercus cellulosae in biopsy
from the brain (H and E stain)
44. Del brutto’s Diagnostic Criteria for
Human Cysticercosis
Del brutto diagnostic criteria
• This has been proposed for the diagnosis of NCC in endemic
countries.
• It is based on clinical, imaging, immunological and epidemiological
– Absolute criteria
– Major criteria
– Minor criteria
– Epidemiologic criteria
47. Echinococcus granulosus
Introduction
• It is also called as dog tapeworm.
• Hartmann was1stdescribed the larval form (hydatid cyst).
Genotypes
• Based on molecular typing the E.granulosus having 10
genotypes.
• The genotypes differ from each other in their intermediate
host, geographic distribution,morphology of adult and larval
stage.
• Genotype G1-G3 cause 88% of human cases.
48. Habitat
• The larval form (hydatid cyst) is found in liver and other viscera
of man.The adult worms reside in dog’s intestine.
Morphology
1) Adult Worm
• It is smaller than other cestodes.measures 3–6 mm long,
consists of head, neck and strobila.
2) Eggs
• Eggs are morphologically similar to Taenia eggs, consists of an
oncosphore with six hooklets surrounded by an embryophore.
3) Larva
• The larval form of E. granulosus is called as hydatid cyst.
49. Life Cycle
1. Definitive host: Dogs
and other canine
animals
2. Intermediate hosts:
Sheep and other
herbivores are
intermediate host.
• Infective form: Eggs are
the infective form
50.
51. Pathogenicity
Hydatid cyst-
• Unilocular, subspherical in shape and size varies from few mm to
more than 30 cm
• It appears as fluid-filled bladder-like cyst
• Cyst wall consists of three layers
1. Pericyst (outer layer, host derived
2. Ectocyst (middle layer, parasite derived)
3. Endocyst (inner layer, parasite derived): It is the germinal layer,
22–25 µm thickness. Its function is to form the ectocyst outside and
on the inner side it forms brood capsule and secretes the hydatid
fluid
53. Hydatid fluid:
• It is clear, colorless to pale yellow,
pH of 6.7 and specific gravity of
1.005 to 1.010.
• Chemical composition: It contains
sodium chloride, sodium sulphate,
sodium phosphate and succinates
54. Clinical Features
• Infection usually occurs in childhood but gets manifested in
adult life.
• Site: Most common site of location of the cyst is liver
(60–70%, right lobe) or lung (20%), kidney (4%), muscle
(4%), etc
• Asymptomatic: Many cases are asymptomatic and
infection is detected only incidentally by imaging studies.
• Symptoms occur due to-Pressure effect of the enlarging
cyst, Obstruction into the biliary tree or a bronchus,
Secondary bacterial infection, and Anaphylactic reactions.
55. Epidemiology
• E. granulosus is worldwide in distribution.
• World: Higher incidence has been reported from
Central Asia (>10 per 1 Lakh population); which may be
up to 27 per 1 lakh population in Tajikistan.
• India: Hydatid disease is reported from various
places in India like Andhra Pradesh and Tamil Nadu,
Chandigarh, Kashmir, Maharashtra and West Bengal.
56. Laboratory Diagnosis
• Hydatid fluid microscopy (direct mount or staining with
acid fast stain)
– detects brood capsules and protoscolices
• Antibody detection- ELISA (using B2t and 2B2t
antigen), DIGFA (dot immunogold filtration assay) and
western blot
57. • Molecular methods- PCR, PCR-RFLP and molecular
typing (10 genotypes, most common in India is type 1).
• Skin test (Casoni test)- demonstrates type I
hypersensitivity reaction.
• Imaging methods- X-ray, USG (demonstrates Water lily
sign), CT scan, MRI
58. • Histological examination (H & E) Giemsa, H & E and
periodic acid-Schiff (PAS) stain-demonstrates cyst wall
and attached brood capsules.
Histopathological section (H & E) showing all three layers of
cyst wall pericyst, ectocyst and endocyst; endocyst with
attached brood capsules.
62. Introduction
• Dwarf tapeworm
• Name Hymenolepis refers to a thin membrane covering the
eggs (Hymen membrane, lepis covering, and nana small
size),
• It is the smallest tapeworm infecting humans.
• 1st discovered by Bilharz (1857)
• It also infect the rodents (mice & rats)
63. Geographical distribution
• The most common tapeworm infection throughout the
world infecting 50–75 million of people.
• Prevalence ranges from 0–4%, with higher prevalence in
children (16%).
64. Habitat
• Adult worms are found in the upper two-third of
the ileum.
• Mice or rats the are found in posterior part of the
ileum.
65. Morphology
The adult form is small, 1–4 cm in length
and consists of head, neck and strobila.
Morphology-3 forms-adult worm, egg and cysticercoid larva
66. Eggs
• Spherical or oval in shape.
• 30-40um in diameter.
• Smooth ,thin & colorless.
• Contains 3 pairs of booklets.
• Non bile stained
68. Laboratory diagnosis
• Stool examination- non bile stained eggs with polar filaments
• between shell membranes
• Eosinophilia
Non bile stained egg of Hymenolepis nana in (A) saline
mount—three pairs of hooklets are seen clearly; (B) iodine
mount
69. Treatment
• Praziquantel (25 mg/kg once) is the treatment of choice,
• Nitazoxanide (500 mg bd for 3 days)
• Niclosamide can also be given.
