Cestodes

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

Micro/PARA – Cestodes by Dra. Bunyi Page 2 of 9

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

Micro/PARA – Cestodes by Dra. Bunyi Page 3 of 9

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

Micro/PARA – Cestodes by Dra. Bunyi Page 4 of 9

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

Micro/PARA – Cestodes by Dra. Bunyi Page 5 of 9

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

Micro/PARA – Cestodes by Dra. Bunyi Page 6 of 9

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

Micro/PARA – Cestodes by Dra. Bunyi Page 7 of 9

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

Micro/PARA – Cestodes by Dra. Bunyi Page 8 of 9

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

Micro/PARA – Cestodes by Dra. Bunyi Page 9 of 9

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