cestodes
TRANSCRIPT
Micro/Para (Dra. Bunyi)
Cestodes
30 January 2008
Cestode Infections Intestinal cestodes
Taenia saginata T. solium Hymenolepis nana H. diminuta Dypillidum caninum D. latum
Extraintestinal cestodes Echinococcus sp. Spirometra
Taenia saginata Known as the beef tapeworm Humans serve only as definitive host (Not a
intermediate host) Human cysticercosis Does Not occur
T. saginata: Morphology
Adult worm
Inhabits upper jejunum May live up to 25 years Measure 4-10m in length (25m) 1,000-4,000
proglottids SCOLEX: cuboidal – 1-2 mm in
diameter 4 acetabula Devoid of hooks or rostellum Mature proglottids
Contain mature male and female reproductive organs
2 large varies and a median clubbed uterus
Follicular testes 300-400
Vagina has a sphincter
Gravid proglottids Proglottids are
longer than they are wide
Uterus is distended with ova and has 15 to 20 lateral branches
Genital pores of proglottids are irregularly shaped
Ova Spherical or
subspherical in shape In color, with a thick
embryophore which appears striated because of numerous pits
Inside the eggshell is the oncosphere or embryo 30-45 µm in diameter
Taenia saginata: Life cycle
Gravid proglottids undergo apolysis passed out/crawls out eggs are released
Cysticercus bovis: infective stage; ovoidal, milky white, 10mm diameter, single scolex invaginated into a fluid-filled bladder
Only 1 adult tapeworm is present in T. saginata infections
T. solium Known as the pork tapeworm of man Man serve as both a definitive host and an intermediate
host
Cams, shar, joy 1 of 9
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Both intestinal and tissue infections occur in manT. solium: Morphology
Adult worm Inhabits the upper small intestines Shorter than T. saginata Less number of proglottids Adults measure 2-4m in length 800-1,000 proglottids
SCOLEX: smaller, more spherical
4 acetabula Cushion-like
rostellum with a double crown of 25-30 large and small hooks
Mature proglottids Presence of
accessory ovarian lobe
Absence of vaginal sphincter
Smaller number of follicular testes 100-200
Gravid proglottids Contains 7-15 uterine
lateral branches Also undergo apolysis but
not very motile Ova
Indistinguishing from T. saginata
T. solium: Life cycle****Same as T. saginata. Pls check above life cycle******
Taenia solium: Pathology and Clinical Manifestations Disease caused
Ingestion of eggs cysticercosis Ingestion of cysticercus taeniasis
Taeniasis symptomsSite Symptoms Pathogenesis
Gastrointestinal Abdominal discomfort, epigastric pain, vomiting
Physical presence of the worm
Other organs (cysticercosis)
Cyst formation in brain, eye, lungs, and liver may cause related symptoms
Physical mass and inflammation
Cysticercosis
T. solium: diagnosis Symptoms History …(naharangan po kasi ng pictures dun sa binigay na
hand-out kaya di mabasa. Kung sino po nakakopya pa-share na lang po. Thanks!)
… Gravid proglottids and/or eggs in the stool Cysticercosis diagnosis
Radiographic localization of cysticercal lesions in tissues
Neurocysticercosis CT Scan findings:
1. Round low-density area without surrounding enhancement after administration of contrast dye (viable larva without inflammation)
2. Ring-like enhancement after injection of contrast dye (dead larva)
3. Small calcified area within a cystic space (dead scolex)Treatment: Taeniasis
Praziquantel: 5-10mg/kg as single dose for both adults and children
scolex expulsion is essential criteria for cure:
recovery of the scolex a negative stool examination 3 months
after treatmentTreatment: Cysticercosis
Neurocyticercosis Praziquantel: 50-75 mg/kg divided into 3
doses for 30 days or Albendazole: 400mg 2x a day for 8-30 days Steroids Surgical removal
Ocular cysticercosis Surgical removal
Epidemiology Related to the habit of eating raw or improperly cooked
meat
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T. solium: Slavic countries, Latin America, Southeast Asia, China and India
T. saginata: Etiopia and East Africa, Japan, SEA, Europe, Australia, Canada, US
Philippines: prevalence of taeniasis – 0.56%; Northern Luzon
Taeniasis: Prevention Adequate cooking of meat Freezing meat below 100C
Hymenolepis nana Common name: dwarf tapeworm Disease caused: Hymenolepiasis nana; dwarf
tapeworm infectionH. nana: Geographic distribution
Primarily limited in human beings to children in warm climates
Prevalent throughout India, parts of the USSR, countries bordering the Mediterranean, all countries of Latin America, Hawaii and some of the islands of South and Southwest Pacific
Common tapeworm in Southeastern USH. nana: Morphology
Adult worm
Length: 25-40mm Number of proglottid: 200
SCOLEX 1. Small and globular2. Bears a short retractile rostellum with a single
ring of 20-30 minute hooklets3. Provided with 4 cup-shaped suckers
Neck – long and slender Immature proglottid – undifferentiated Mature proglottid
1. Trapezoidal about 4x as broad as long2. Has a single genital pore on its left side
towards the anterior border3. Has 3 round testes and a bilobed ovary
Ripe or gravid proglottid – contains the sacculate uterus filled with eggs
Ova Grayish hyaline,
nearly spherical 20-40µm in diameter Two thin
membranous shells
Inner membrane with two polar thickenings each provided with 4-8 threadlike filaments extending into the space between the two shells
Hexacanth embryo with 6 hooklets enclosed by 2 membranes
H. nana: Life cycle
H. nana: Epidemiology Human strain
Only human tapeworm that does not require an intermediate host to complete its life cycle
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Man is the natural final host Infective stage is the
embryonated ova transmitted to man through the agency of foods and drinks particularly raw leafy vegetables usually eaten as raw salad
It is more common in children and in institutionalized group
Humanity is the chief source of infection Murine strain, H. nana var. fraternal
Final hosts are rats and mice Man is an accidental final host Intermediate hosts are fleas and beetles Infection of definitive hosts results from the
ingestion of intermediate hosts harboring the 4cysticercoid larva
H. nana: Mode of Transmission Direct hand to mouth Less frequently, by contaminated food or water Possibly, by indirect intermediate hosts
H. nana: Symptomatology Infection with a few H. nana may produce no symptoms It may be responsible for:
1. Diarrhea2. Anorexia3. Vomiting4. Insomnia5. Loss of appetite and weight6. Irritability7. Pruritus of the anus and nose8. Urticaria9. Choreiform symptoms
Heavy infection is invariably pathogenic1. Moderate to profuse diarrheic stools2. Abdominal pain3. Anorexia and exaggerated disorders4. Extreme apathy5. Epileptiform seizures
H. nana: Laboratory Diagnosis Recovery of the characteristic ova in the stools Light cases with the aid of acid ether
concentration techniqueH. nana: Treatment
Praziquantel – 25 mg/kg in single dose Niclosamide – 2 g each day for 5-7 days
Children – half of the adult dose Paromomycin – 45 mg/kg daily, given in 4 doses at
hour intervals for a period of 5 daysH. nana: Prevention
Human strain
a. Avoid ingestion of eggs by not eating raw vegetables or salad
b. Personal hygienec. Cleanliness of toilet seats
Murine straina. Eradicate the rats and mice around the houseb. Residual spraying of their nests and burrows
with insecticidesc. Protection of cooked foods from arthropods
Hymenolepis diminuta Common name: Rat tapeworm Disease caused: Hymenolepiasis diminuta; rat
tapeworm infectionH. diminuta: Geographic distribution
Cosmopolitan parasite of rats, mice, and other rodents
Has been reported from human hosts usually from children in India, Indonesia, USSR, Japan, Philippines, S. Europe, Latin America from Argentina to Mexico and Cuba and from several parts of the US
H. diminuta: Morphology Adult worm
Length: 10-60cm by 3-5mm Number of proglottids: 800-
1,000 SCOLEX
Knob-like; club-shaped Provided with a rudimentary
apical unarmed rostellum or a deep apical suctorial pocket without rostral hooklets
Provided with four relatively small cup-shaped suckers
Neck – short and stout Immature proglottid – undifferentiated Mature proglottid
0.8 by 2.5mm Same as H. nana only
the segments are larger
Ripe or gravid proglottid – sacculate uterus with egg masses
Ova Hyaline with straw-colored hue Broadly ovoid or
subspherical 58 by 86µm 2 egg membranes,
outer and inner Inner membrane with 2
polar thickenings but with the absence of filaments
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Considerable space between outer and inner Hexacanth embryo enclosed by 2
membranesH. diminuta: Life cycle
H. diminuta: Epidemiology Man is only an accidental final host Rats and other murines are the natural final hosts Principal intermediate hosts are the larval rat, mouse
fleas and adult mealworm beetle Other intermediate hosts – fleas, myriapods,
cockroaches, beetles, lepidopterans Infective stage to the final host is the cysticercoids larva
in the arthropod host Humans are infected accidentally by food or hands
contaminated with infected insectsH. diminuta: Symptomatology
H. diminuta usually produces no symptoms Indigestion and abdominal pain are the presenting
complaints in infantsH. diminuta: Lab Diagnosis
Recovery of the characteristic ova in the stoolsH. diminuta: Treatment
Same as H. nanaH. diminuta: Prevention
Eradicate the rats and mice around the house Residual spraying of their nests and burrows with
insecticides Protection of cooked foods from arthropods
Dipylidium caninum Common name: Double-pores dog tapeworm Disease caused: Dipylidiasis; dog tapeworm infection
D. caninum: Geographic Distribution A common tapeworm of the dog and cat throughout
the world; also reported from wild cats and foxes
Human infection is rare but reported from European, China, and the Phils.
In the Phils., survey of dogs – prevalence of 5.19% - 36%; dog and cat fleas – 2.4%
Dipylidium caninum: Morphology Adult worm
Pale reddish adult worm measuring 15-70cm in length
Strobila – a chain of melon-shaped proglottids
Number of proglottids – 60-175
SCOLEX Rhomboidal Retractile conical
rostellum armed with 30-150 rose thorn-shaped hooklets arranged in transverse rows
4 prominent oval suckers Neck – short and slender Immature proglottid
Broader than long when very young Square as they become older
Mature proglottid Vase-shaped,
melon seed-shaped or pumpkin seed-shaped
Double sets of reproductive organs Genital atrium on each side of the segment
Gravid proglottid Vase-shaped, melon seed-shaped or pumpkin
seed-shaped Filled with polygonal shaped uterine egg
pockets or egg capsules containing 8 to 15 eggs
Ova Spherical Thick
albuminous covering Hexacanth
embryo with 3 pairs of lancet-shaped
hookletsD. caninum: Life cycle
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D. caninum: Epidemiology Definitive hosts are dogs, cats and wild carnivore Man especially children are only accidental final hosts Intermediate hosts are larval fleas of the dog, cat and
human being and the dog louseo Dog flea – Ctenocephalides caniso Cat flea – C. feliso Human flea – Pulex irritanso Dog louse – Trichodectes canis
Ingestion of the infected fleas cause infection of the final host
Infants and young children are usually infected because of their close contact with their pet cats
D. caninum: Symptomatology Light infections – asymptomatic May cause:
1. Slight intestinal discomfort2. Epigastric pain3. Diarrhea4. Anal pruritus5. Allergic reactions
D. caninum: Diagnosis Clinical – difficult since symptoms are non-specific Laboratory
Based upon the demonstration of:1. A single or chain of melon-shaped
proglottids2. Egg pockets or egg capsules3. Embryonated ova4. Ripe or gravid proglottid
D. caninum: Treatment Praziquantel – 10mg/kg in a single
dose Niclosamide – 4 tablets (2g) chewed
thoroughly in a single dose after a light meal
Paromomycin – 1g every 4 hours for 4 doses Quinacrine hydrochloride – 0.8g given over a half
hour intervalD. caninum: Prevention
Periodic deworming of pet cats and dogs is recommended
Insecticide dusting of dogs and cats are effective against fleas
The potential danger of playing with pets must be included in the health education of children
Small children should not be allowed to fondle dogs and cats infected with fleas and lice
Diphyllobothrium latum Common name: Broad or fish tapeworm Disease caused: Diphyllobothriasis; fish tapeworm
infection; broad tapeworm infectionD. latum: Geographic Distribution
Prevalent in regions of the temperate zones where freshwater fish form an integral part of the diet
Common in N. Europe, N. America, Manchuria and Japan and S. America
Has been reported in man once from the Phils.D. latum: Morphology
Adult worm Ivory or grayish
yellow Length – 3-10m Number of
proglottids – 3,000 SCOLEX
Spatulate, almond-shaped
2-3mm by 1 mm
N rostellum nor hooklets
2 deep dorsoventral suctorial grooves called bothria
Neck – unsegmented, several times the length of the scolex
Mature proglottid Broader than
long Contains both
male and female reproductive organs
Characteristic morphologic feature – dark rosette-like coiled uterus at the center
Ripe or gravid proglottid – same as mature proglottid
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Ova Yellowish brown Measures 55-
76µm by 41-56µm Inconspicuous
operculum at one end
Small knob-like thickening at the other end Contains plenty of yolk cells Immature when oviposited
D. latum: Life cycle
D. latum: Epidemiology The final hosts are man and other piscivorous mammals
such as dog, cat, leopard, foxes, mink, pig, bears 1st intermediate hosts – copepods of the Genus
Diaptomus and Genus Cyclops 2nd IH – freshwater fish like pike, trout, salmon,
whitefish, turbot and carp in the Phils. Infective stage to man and other hosts – plerocercoid
larva in the 2nd intermediate host Usual vehicle for transmission – raw, partially
cooked or frozen fish eaten rawD. latum: Diagnosis
1. Clinical Tapeworm appetite, abdominal pain and
anemia particularly in people living in endemic areas
2. Laboratory Demonstration of the characteristic egg I
the stool using acid ether concentration technique
D. latum: Treatment1. Niclosamide – 4 tablers (2g) chewed thoroughly I a
single dose after a light meal2. Paromomycin – 1g every 4 hrs for 4 doses3. Praziquantel – 10mg per kg in a single dose
4. Quinacrine HCl – 0.8g given over a half hour interval
D. latum: Prevention Thorough cooking of all fresh water fish and used for
human consumption Freezing of fish for 48 hrs at a temperature of -10oC Tasting of raw freash water fish while being prepared
for the table should not be practiced Proper treatment and disposal of sewage
SparganosisA. NONBRANCHING SPARGANA Spargana or plerocercoid larva of several species of
Spirometra (Diphyllobothrium) mansonoides – found also in humans
Geographic Distribution Found in East and SE Asia, Japan, Indochina and to
a lesser extent North and South AmericaMorphology
Elongated, ivory white ribbonlike larvae
Has an antero-posterior polarity Pseudosucker Elongated like a small tapeworm No scolex and no defined
proglottidsLife cycle
Similar to D. latum
Epidemiology The final hosts are dogs and cats The first intermediate hosts are the copepods of the
Genus Cyclops The 2nd IH are the frogs, lizards, snakes, birds and
monkeys Man is an accidental IH The infective stages are:
Porcercoid larva in the Cyclops Plerocercoid larva (spargana) in the tissues of
cold blooded vertebrates
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Human infection results from: Ingestion of Cyclops infected with procercoid
larva Ingestion of raw flesh of cold blooded animals
harboring thespargana Local application of the flesh of cold
blooded vartebrates harboring the spargana
Pathogenesis and Symptomatology Found in any part of the body especially:
Eyes Subcutaneous and muscular tissues of the
thorax Abdomen Thighs Inguinal region Thoracic vertebra
Elongating and contracting larvae within a slimy matrix cause an inflammatory and painful edema of the surrounding tissue
Degenerated larvae cause intense local inflammation and necrosis but no fibrous tissue formation
Infected persons may show: Local indurations Periodic giant urticaria Edema Erythema accompanied by chills, fever and
high eosinophilia Ocular infection – painful edematous
conjunctivitis with lacrimation and ptosisDiagnosis
By finding the larvae in the lesionTreatment
Surgical removal of the larval plerocercoidPrevention
Only potable water should be drank Raw water from streams should be avoided as this may
contain infected Cyclops Use of cold blooded vertebrates as poultices should be
avoided Cold blooded vertebrates when eaten should be in
a cooked stateSparganosis
B. BRANCHING SPARGANA Budding larval tapeworm – Spirometra proliferum
Geographic Distribution Reported in Japan and US
Morphology LARVA – irregular, lateral, supernumerary processes
that may bud off as new spargan in the tissuesLife cycle
unknown
Diagnosis Finding the larvae in the chylons nodular lesions
Echinococcus Disease caused by the larval stage which is acquired
when eggs are ingested E. granulosus – causes hydatid cysts E. multilocularis – alveolar echinococcosis Dogs and other canines are the most common
definitive hostsE. granulosus (hydatid): Geographic Distribution
E. granulosus (hydatid): Morphology ADULT WORM
3-6mm length Possess pyriform, scolex, short neck and 3
proglottids (immature, mature, and gravid) Hydatid cyst – usually measures 1-7cm in diameter
Consists of protoscolices The cysts (2-30cm) are constituted by an
external acellular cuticle and an inner cellular “ germinal” layer (10-25µ) that produces the brood capsules containing 6-12 protoscolices or single protoscolices (Germinal layer with a protoscolex)
“Hydatid sand” – free protoscolices in the cyst
Fluid aspirated from a hydatid cyst will show multiple protoscolices (size approx. 100µm), each of which has typical hooklets
The protoscolices are normally invaginated (left), and evaginate (middle, then right) when put in saline
E. granulosus: Life cycle
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E. granulosus: Pathogenesis and Symptomatology Pathology caused by developing larval cyst in the
intermediate host LIVER: most common and most important site of
involvement (70%); 85% located in the right lobeSite Percentage of casesAbdomenLiver 75% Abdominal pain,
hepatic mass, bile duct obstruction
Lung 22% Chest pain, cough, hemptysis
CNS* guys, di ko na mabasa yung nakalagay ulit kaya sensya na at incomplete to..dont know where they got this pero may i-aadd na lang ako from the net na siguro would describe whats supposed to be here.
The symptoms, comparable to those of a slowly growing tumor, depend upon the location of the cyst. Large abdominal cysts produce increasing discomfort. Liver cysts cause obstructive jaundice. Peribronchial cysts may produce pulmonary abscesses. Brain cysts produce intracranial pressure and Jacksonian epilepsy. Kidney cysts cause renal dysfunction. The contents of a cyst may produce anaphylactic responses.
E. granulosus: Diagnosis Endemicity Symptoms X-ray and CT scan Serology Skin (Casoni) test
Serology
Indirect hemagglutination (IHA), indirect fluorescent antibody (IFA) tests, and enzyme immunoassays (EIA)are sensitive tests for detecting antibodies in serum of patients with cystic disease
Sensitivity rates vary from 60 – 90% Postivet reaction is confirmed by immunoblot assay or
any gel diffusion assay that demonstrates the echinococcal “ Arc 5”
Cansoni test An intermediate hypersensitivity skin test used to
detect sensitization to hydatid antigen
E. granulosus: Treatment and Control Surgical removal of cyst Praziquantel Avoidance or treatment of
infected canineFor inoperate cysts – PAIR (Puncture, aspiration, injection, reaspiration)
E. multilocularis Foxes are the natural
definitive host Small rodents are the IH Humans infected by eating raw plants contaminated
with feces of infected canine or cats Cyst wall – not clearly delineated from
surrounding tissue; porous, spongy mass of small irregular cavities with a jelly like matrix
Echinococcosis
E. multilocularis: Treatmend and Control Surgical removal of the cyst Resistant to praziquantel Albendazole has some effect Avoidance control of rodent population