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Platyhelminths 2 Cestoidea

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Presentation on theme: "Platyhelminths 2 Cestoidea"— Presentation transcript:

1 Platyhelminths 2 Cestoidea
David Humber

2 Cestodes - Tapeworms Endoparasites No mouth or alimentary tract
Attachment organ - anterior Elongated body - divided into proglottids Adults in intestines of vertebrates Larval stages in 1 or 2 intermediate hosts

3 Cestoidea Tissue & Intestinal
Disease Hydatid disease (6k) Hydatid disease (rare) Coenurosis (rare) Sparganosis (rare) Sparganosis (?) Cysticercosis (?) Tissue cestodes (extra-intestinal) Echinococcus grqnulosa Echinococcus multilocularis Multiceps spp Spirometra mansonoides Diphyllobothrium spp Taenia solium

4 Cestoidea Tissue & Intestinal
Intestinal Cestodes Diphyllobothrium latum Taenia solium Taenia saginata Hymenolepis nana Hymenolepis diminuta Dipylidium canis Cases 16 million 5 million 76 million 36 million Rare

5 Intestinal Cestodes Tapeworms
Attached via a scolex to mucosa (small intestine) Composed of proglottids forming a strobila Each proglottid contains male & female reproductive organs Immature >> Mature >> Gravid

6 Tapeworms Hymenolepis nana Taenia saginata - Taenia solium
Dwarf tapeworm (upto 40mm - largely children) Taenia saginata - Beef tapeworm (upto 25m) Taenia solium Pork tapeworm (upto 7m) World-wide distribution

7 Hymenolepis nana Dwarf Tapeworm
Intermediate host not required infection via intermediate insect host rare commonest tapeworm in UK and US (<1%) Eggs via oral-faecal route Hatch in stomach/small intestine Larvae (onchospheres) penetrate villi Develop into cysticercoid stage Migrate back into lumen

8 Hymenolepis nana Dwarf Tapeworm
Maturation 2-4 weeks Length dependent on parasitemia Scolex - 4 suckers + short rostellum with hooks Eggs released by disintergration of terminal proglottids Eggs immediately infectious

9 Hymenolepis nana Dwarf Tapeworm
Often asymptomatic even with high worm burden headache, dizziness, anorexia, abdominal pain, diarrhea, low grade eosinophilia Heavy infections via auto infection (in intestine) Diagnosis by egg morphology (adults v rarely seen)

10 Hymenolepis nana Control
World-wide incidence 4% Treatment usually Praziquantel previously Niclosamide (both single oral dose) Health education Rodent reservoir?

11 Taenia saginata Beef Tapeworm
Commonest taenia infection (Ethiopia) Ingestion of raw or poorly cooked beef Larvz digested & evaginates in small intestine Scolex 4 suckers no hooks Proglottids 1-2k (lateral unterine branches 15-20)

12 Taenia saginata Beef Tapeworm
Motile proglottids crawl through anus during day Eggs identical to T. solium (viable upto 159 days) Larvae (onchospheres) hatch in cattle intestine Migrate through villi via lymphatics/blood to striated muscle Develop into cysticerci (bladder worm)

13 Taenia saginata Beef Tapeworm
Usually asymptomatic hunger pains, weight loss discomft & embarrassment at voiding proglottids Diagnosis based on recover of gravid proglottid (uterine branches >15) Praziquantel or niclosamide Health education

14 Taenia solium Pork Tapeworm
Recognised since biblical times Risk of cysticercosis Evagination > six hooked four suckers larva (onchophore) in small intestine Attaches to mucosa (penetrates in cysticercosis) Matures in 5-12 weeks Usually long lived (25 years) single worm Less than 1000 proglottids

15 Taenia solium Pork Tapeworm
Usually asymptomatic similar to S. saginata Low grade eosinophilia <15% Treatment praziquantel niclosamide

16 Taenia solium Cysticercosis
Onchospheres penetrate intestine (adult worm not usually found) Distributed via mesenteric venules Most organs including brain, eyes, sucutaneous and intramuscular Sometimes multiple organs (geographical variations)

17 Taenia solium Cysticercosis
Bladder worms upto 60ml in volume (usually around 5 x 800 mm) Diagnosis surgical removal X ray - calcified larvae CT scan or MRI for brain lesions Fine needle aspirate Serology/PCR

18 Taenia solium Cysticercosis
Treatment surgical removal praziquantel (15 day course) only treatment for cysticercus albendazol (8 day course)

19 Tissue Cestodes Taenia solium Echinococcus grqnulosa
Echinococcus multilocularis Diphyllobothrium spp Multiceps spp Spirometra mansonoides

20 Echinococcosis - Hydatid disease
Echinococcus granulosa worldwide Echinococcus multilocularis Europe, Russia, China, Canada Echinococcus vegeli Central & South America

21 Distribution

22 Hydatidosis Known since Hipporates 400BC
Most serious of the tapeworm infections

23 Hosts Definitive Host Intermediate Host Canids & felids
59% dogs in Istanbul (E.granulosa) Intermediate Host humans +60 species ungulate,marsupials, elephants,primates, rodents for E. multilocularis

24 Lifecycle Definitive host Intermediate host
Egg production Worm lives 2+ years Cyst evaginates Intermediate host Hatch - onchosphere invades mucosa & penetrates capillaries Cysts form in liver & lungs Secondary metastasis 20+ years Secondary daughter cysts bud in E. multilocularis

25 Clinical Features Definitive Host Intermediate Host
usually asymptomatic Intermediate Host dependent on burden & site usually single - 50% in liver, 3% brain (E.g) incubation +5 years 6-10% diagnosed cases fatal Eosinophilia in 25% cases

26 Diagnosis Parasitological Radiological (CT & MRI) & ultrasound
eosinophilia palpation Radiological (CT & MRI) & ultrasound differente from tumor Immunological Skin test - Casoni test - 18% false +ves Serology

27 Treatment & Control Surgery Praziquantel or albendazol
drainage + 5 mins 10% formalin Praziquantel or albendazol steroids to prevent inflammation aspiration + 95% ethanol Health education sanitation - dogs cats raw meat

28 Diphylobothrium - Sparganosis
Diphylobothrium latum Broadfish tapeworm Definitive host humans/dogs/cats/pigs/bears/otters, seals etc First intermediate host Copepods Second intermediate host trout/salmon/perch/pike

29 Intestinal infections
Limited to fish eating areas raw or improperly cooked dumping untreated raw sewage Adult worms (upto 10m) attach to lining of intestine Ovoid operculated eggs released Eggs dormant in water (8-12 days) motile coracidium hatches ingested by freshwater copepod

30 Intestinal infections
Ciliated embryophore shed & naked hexacanth larva attaches by hooks Bores through intestinal wall into haemocoel Hexacanth metamorphose into procercoid (14-18 days) 500um in length

31 Intestinal infection In fish procercoid penetrates intestinal wall
migrates to muscles develops into plerocercoid (20-40mm) in 7-30 days with fully developed scolex In definitive host attaches to mucosa grows at 30 proglottids a day Full sexual maturity in 3-5 weeks

32 Sparganosis Some species of Diphylobothrium and Spirometra
larva invade

33 Nematode Infections

34 Nematodes Half million species 50% free living
animal & plant parasites Animal vertebrate & invertebrate hosts infection by ingestion penetration

35 Nematodes Generally elongated, cylindrical & tapered at each end (99%)
fluid filled pseudocoelom logitudinal muscle only no vasculature or respiratory system usually sexual dimorphism (some parthenogenetic) males usually smaller than females most between 1mm and 150mm colourless translucent to opaque with an elastic curticle

36 Ascaris Large intestinal round worm
mouth with I dorsal & 2 ventral lips female 40cm male 30cm Uterus of mature female 20+ million eggs Sheds 200,000 golden brown ovoid eggs per day Eggs resistant to desiccation

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