Class of Cestodes

D. Latum Taenia Saginata Taenia Solium Hymenolepis NanaMorphology - 3000-4000 segments

- Scolex is elongate, spoon-shaped

- 2 longitudinal bothria- Neck is followed by

immature, mature and gravid segment

- Mature segment Broader than long Mid-ventral genital

pore- Testis are multiple and

dorsolateral- Vas deferens – seminal

vesicle – cirrus – common genital pore

- Bilobed ovary posterior- Vitelline glands ventro-

lateral- Ootype- vagina – common

genital pore- Coiled rossete shaped

uterus- Gravid segments

Uterus is darker, more coiled, rossete shaped and packed with eggs

- 1000 to 2000 proglotids- Scolex is quadrate- Unarmed- 4 hemispherical suckers- Neck –immature-

mature-gravid segments- Mature segments:

Broader than long

300-400 testis Blind tubular

uterus Bilobed ovary Vagina with

terminal sphincter

- Gravid segment detached singly

- Eggs developed singly in thin hyaline capsule

- Eggs have a thick brown striated embryophore surrounding the hexacanth embro or oncosphere

Differences from T Saginata- Shorter in lengths- Less segments- Scolex is globular with

rostellum and hooks- Less number of testis

150- Ovary is trilobed- Gravid uterus possesses

7-13 lateral branches

- Scolex is rhomboids- Four suckers- Short rostellum with

20-30 spines- Neck is long and slender- 100 segments broader

than long

Mature segments- 3 globular testis- A small lobed ovary,

Vitelline glands and uterus occupy the middle part

Gravid segment- Sac-like uterus- 80-100 eggs- 2 thin shells- Inside the embryophore

is the hexacanth embryo

- Eggs are immediately infective once formed

Life Cycle - Eggs are passed in stools - Eggs are ingested by - similar to T. Saginata Refer picture in books

- Immature, ovoid and operculated

- Mature in fresh water- Coracidium (ciliated

hexacanth embryo)- 1st int host: Cyclops- Loses cilia- Procercoid larva (1st larval

stage)- 2nd int. host: fish- Plerocercoid larvae (2nd

larval stage and infective stage)

- Mucous membrane of small intestine

- Adulthood

cattle- Intestinal wall- Mesenteric venules- Circulation then muscles- Cysticercus bovis

(infective stage)- man is the sole definitive

host- intestinal mucosa

- intermediate host is pig- gravid segments passed

in stools- ingested by pigs- shells disintegrate- oncospheres- metamorphos into

cysticerci- larval and infective

stage: cysticercus cellulosae

- wall of small intestine- maturity- man can be

intermediate host leading to cysticercosis

Pathogenesis - Pathological effects depends on:

Number of worms Competition for

nutrients Amount of

metabolic by-product absorbed by hosts

- Changes in motility and secretion of GIT

- Gastric secretion is reduced

- Slight irritation at mucosa

- Rarely cause intestinal obstruction

- Well tolerated- allergic

Clinical Picture - Asymptomatic- Diarrhoea, abdominal pain- Pernicious anaemia- Intestinal obstruction

- Abdominal pain, nausea, increase/decrease appetite and/or body weight

- Abdominal discomfort, weakness, insomnia and irritability

- Allergy is rare

- Abdominal discomfort, hunger pains, diarrhoea

- Diarrhoea alternating with constipation

- Loss of appetite

- Asymptomatic- Headache, dizziness,

anorexia, periodic diarrhoea and abdominal pain

- Intestinal obstruction- Acute appendicitis- Cholangitis

Diagnosis - Eggs or segments in faeces - Difficult in 1st 3 months- Gravid proglotids in

faeces- Rarely eggs

- Gravid segments in stool examination

- Rarely eggs- Counting the main

lateral brances

- Stool samples

Treatment - Niclosamide- Praziquantel

- Niclosamide (yomesan)- Praziquantel

- Niclosamide- Praziquantel

- Niclosamide- Praziquantel