class cestoda pathology and parasitology course code: 401 parasitology-lab #3 department of...

Class Cestoda

Pathology and ParasitologyCourse Code: 401

Parasitology-lab #3

Department of Microbiology & ImmunologyFaculty of Pharmacy

Cairo University

General CharactersTapeworms

1- All worms have long flat (no body cavity), multi-segmented body.

2- The body is covered with a cuticle that is provided with pores through which the worm uptakes its nutrients (no digestive system).

3- All are hermaphrodites (each segment contains both male and female sexual organs).

4- The adult worm is divided into 3 distinct parts: a- Head or Scolex: usually with 4 muscular suckers and a crownof hooks (rostellum) to attach to theintestinal wall.

b- Neck Region: serves as a generative organ

c- Strobilla: three types of segments (Proglottids). i. Immature: following the neck region

ii. Mature: containing both sex organsand responsible for reproduction iii. Gravid: filled with fertilized eggs

5 -Eggs: contain hexacanth

embryo (oncosphere).

6- All cestodes have an intermediate host except Hymenolepis nana(may have or maynot).

Examples of Class Cestoda1- Taenia sp. Taenia saginata Taenia solium

2- Hymenolepis sp. Hymenolepis diminuta Hymenolepis nana

3- Dipylidium caninum

4- Echinococcus granulosus

General life cycle of Cestodes

1. The adult worm matures in human intestine (final host). 2. Eggs shed in feces are released into environment.3. Eggs are eaten by grazing animals (intermediate host).4. Larval forms encyst in animals’ tissue.5. Humans ingest encysted larvae in meat of infected animal

(except in case of Echinococcus granulosus).

Taenia saginata (Beef Tapeworm)Length: up to 10 m

• Location of adult: small intestine of man• Intermediate host : cattle (beef)• Infective stage : Cysticercus bovis• Mode of transmission: eating

insufficiently cooked meat containing Cysticercus bovis

• Diagnosis: eggs & gravid segments in stool

• Disease: Taeniasis Taenia saginata mature segment: nearly square, bilobed ovary, scattered testis, uterus: median tube (magnifier)





• Disease: Taeniasis





• Disease: Taeniasis Taenia saginata gravid segment longer than broad branched uterus filled with eggs (magnifier)





• Disease: Taeniasis

Circular with radiating (striated) double wall

(H.P)

Hymenolepis diminuta (Rat Tapeworm)

Length: 20-60 cm• Location of adult: small intestine

of rat occasionally man• Intermediate host: rat flea• Infective stage: cysticercoid• Mode of transmission: ingestion

of rat flea containing cysticercoid • Diagnosis: eggs and gravid

segments in stool• Disease: hymenolepiasis

Mature segments: Broader than long characterized by 3 testis and one ovary in each segment (magnifier)






Gravid segments: Broader than long, enlarged uterus containing eggs (magnifier)

Hymenolepis nana (Dwarf Tapeworm)

Length: Very small 15-40 mm

Hymenolepis nana

(Dwarf Tapeworm)So there are 2 different routes in this life cycle: 1-without intermediate host

2-with flea as intermediate host

• Location of adult: small intestine of man

• Intermediate host: none• Infective stage: eggs• Mode of transmission: eating food

contaminated with eggs or autoinfection

• Diagnosis: eggs in stool• Disease: Hymenolepiasis



Mature segments: broader than long, characterized by 3 testis and one ovary in each segment (L.P)

• Location of adult: small intestine of man and rodents

• Intermediate host: flea• Infective stage: cysticercoid • Mode of transmission: ingestion of

cysticercoid –containing flea • Diagnosis: eggs in stool• Disease: Hymenolepiasis



Mature segments: broader than long, characterized by 3 testis and one ovary in each segment (L.P)

Dipylidium caninum (Dog Tapeworm)

Length: 10-50 cm

• Location of adult: small intestine of dogs, occasionally man

• Intermediate host: dog flea• Infective stage: cysticercoid• Mode of transmission: ingestion

of dog flea containing cysticercoid• Diagnosis: egg packet in stool• Disease: Dipylidium caninum

infection

Cucumber seed-like or barrel shape

Mature segment: Longer than broad, 2 genital pores, testis and ovaries

(magnifier)


Gravid segment: Longer than broad, deformed wall, enlarged uterus filled with eggs

(magnifier)

Scolex: showing 4 suckers and extended rostellum with four rows of hooks (L.P)


Length: 10-50 cm




infection


Length: 10-50 cm




infection

Egg Packet: round to oval and containing 5-15 eggs (H.P)

Infective Stage

Diagnostic Stage

Intermediate Host

Final Host

Man (End Stage intermediate Host)

Echinococcus granulosus (Hydatid Tapeworm) Length: 3-9 mm

Echinococcus granulosus (Hydatid Tapeworm)

Length: 3-9 mm

• Location of adult: small intestine of dogs• Location of hydatid cyst : liver, lung,

CNS and bone in man, cattle and sheep• Intermediate host: cattle, sheep (man is

an end stage intermediate host)• Infective stage (for human): eggs in

feces• Mode of transmission: man is infected

by ingestion of eggs in dog feces • Diagnosis: identification of hydatid cyst

by X-ray• Disease: hydatid disease

Adult worm: scolex, immature, mature and gravid segments (4X)


Length: 3-9 mm







Protoscolex from hydatid cyst

(H.P)


Length: 3-9 mm








Length: 3-9 mm







Echinococcus granulosus hydatid cyst

class cestoda pathology and parasitology course code: 401 parasitology-lab #3 department of...

Documents

taeniasis slide

eggs magnifier slide

fertilized eggs slide

cysticercus bovis diagnosis

eggs gravid segments

taenia saginata taenia

p slide

location of adult