Cestodes Final.pptx

Cestodes ( Tape Worms ) General Characters of Cestodes Body : Tape – like, consists of multiple segments  Proglottidis Hermaphrodite : each segment contains male and female organs Head ( Scolex ) : has suckers OR grooves OR hooks for attachment No mouth and no digestive system...

Cestodes ( Tape Worms ) General Characters of Cestodes Body : Tape – like, consists of multiple segments  Proglottidis Hermaphrodite : each segment contains male and female organs Head ( Scolex ) : has suckers OR grooves OR hooks for attachment No mouth and no digestive system. Nutrients are absorbed directly through the body surface Cestodes General Characters 4 Medically Important Cestodes Taenias 1. Taenia saginata ( Cow Tape worm ) 2. Taenia solium ( Pig Tape worm ) Echinococcus granulosus ( Hydatid Cyst ) Diphylobothrium latum ( Fish Tape worm ) Hymenolepis nana ( Dwarf Tape worm )  Taenia saginata ( Cow Tape worm ) Transmission Eating under – cooked cow meat that contains infective larva Cysticercus bovis : bladder filled with fluid and has inverted scolex Length of adult worm 5 – 20 meters Definitive host: Humans only Intermediate host: Cows Clinical Features Taenia saginata disease Abdominal pain Nausea Loss of weight Diarrhoea Patient may notice passage of worm segments in faeces No eosinophilia Intestinal obstruction ( uncommon ) Diagnosis of Taenia saginata disease Clinical features Laboratory tests 1. Microscopy of faeces for Eggs ( has striated radiations on the egg shell) 2. Identify proglottid segment. Uterine branches > 13  Treatment of Taenia saginata disease Praziquantel Yomesan ( Niclosamide ) Taenia solium ( Pig Tape Worm ) Transmission : by eating under – cooked pig meat that contains infective larva Cysticercus cellulosae Less common but more serious than Taenia saginata Taenia solium larva  Cysticercus cellulosae  Neuro – Cysticercosis  Epilepsy Length of adut 2 – 5 meters ( smaller than T saginata )  Clinical Features Taenia solium disease Abdominal pain, Nausea, Diarrhoea, Loss of weight Taenia solium larva Cysticercus cellulosae  Brain : Neuro – Cysticercosis  Epilepsy  Skin : Sub- Cutaenous nodules  Bone : Bone – Cysticercosis  Fracture  Eye : Retinitis Cysticercus cellulosae Larva of Taenia solium Muscle tissue Larva Cysticercus cellulosae  Diagnosis Laboratory tests 1. Microscopy for eggs ( similar to T saginata ) in faeces 2. Identify scolex: 2 rows of hooks + 4 suckers 3. Identify proglottid segment: Uterine branches < 13 Diagnosis of Cysticercus cellulosae larva 1. Serology 2. X – Ray 3. CT and MRI  Treatment Praziquantel Yomesan ( Niclosamide ) Treatment of Cysticercus cellulosae larva Surgical treatment Praziquantel Albendazole Echinococcus granulosus ( Dog Tape worm )  Hydatid Cyst Hydatid cyst is the Larva stage of Echinococcus granulosus inside human tissues It is zoonosis maintained in nature between dogs and sheep + other herbivores Dog : Definitive Host Sheep + other herbivores : Intermediate Host Humans : Accidental Intermediate Host Transmission Dog  Eggs in faeces  contaminate food or water  Humans ingest eggs in contaminated food or water  Larva ( Hydatid cyst ) in any tissue, usually Liver, Lungs, Brain, Bone  Hydatid Cyst Larva of Echinococcus granulosus ( Dog Tapeworm ) Composed of 3 layers 1. Outer fibrous layer 2. Middle laminated layer 3. Inner germinal layer  Pathogenesis of Hydatid Cyst Larva of Echinococcus granulosus Tape Worm Hydatid cyst  Mechanical pressure  ischaemic changes  Pain Hydatid cyst  may rupture  Fluid and parasite act as Antigens  Allergy OR Anaphylactic symptoms  Clinical Features of Hydatid Cyst Small cyst  Asymptomatic: discovered on routine X – Ray Mechanical pressure  Pain ( depending on the organ involved ) Hepatomegally Allergy OR Anaphylactic symptoms due to cyst rupture  Diagnosis of Hydatid Cyst X –Ray CT and MRI Serology Microscopy of fluid in cyst removed by surgery  for scolex  Treatment of Hydatid Cyst Surgical treatment ( Main line of treatment ) Sterilization of cyst by agents that kill the scolex: Examples : Ethanol, Chlorhexidine, Hypertonic solutions Drugs Albendazole Mebendazole Praziquantel  Diphyllobothrium latum ( Fish Tape worm ) Common in Europe Large tape worm 10 – 13 meters Scolex : elongate with 2 grooves ( bothria ) Eggs : Large and has operculum ( cover at one pole ) Habitat : Small Intestine  Transmission and Life Cycle of Diphyllobothrium latum ( Fish Tape Worm ) By eating under – cooked fish that contains infective larva Definitive host : Humans Intermediate host : Has 2 intermediate hosts 1. Cyclops ( water flea ): that contains Procercoid Larva 2. Fish: that contains Plerocercoid Larva  Diphyllobothrium latum Fish Tape Worm Clinical Features Abdominal pain Diarrhoea Vitamin B12 deficiency anaemia ( Worm competes with Host for Vit B12 ) Diagnosis Microscopy for egg stage Treatment Praziquantel Yomesan Vitamin B12 supplement  Hymenolepis nana Transmisssion and Life Cycle  Hymenolepis nana Dwarf Tape Worm The smallest and most common tape worm found in humans, mainly in children. Habitat : small intestine Adult length: About 3 cm Clinical Features: Abdominal Pain, Diarrhoea, Pruritus and Irritability Definitive Host: 1. Humans 2. Rats Intermediate Host: Rat Fleas Diagnosis : Microscoy of faeces for eggs Treatment : 1. Praziquantel 2. Niclosamide  Suggested References ( 1 ) Parasitic Diseases Division , CDC www.cdc.gov/nczved/divisions/dpd (2) Levinson Microbiology & Immunology ( 3 ) Essentials of Human Parasitology by J S Heelan and F W Ingersoll 30