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62 Cards in this Set
- Front
- Back
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Tapeworms (Cestodes) and Flukes (Trematodes) fall under what phylum? |
PLATYHELMINTHES = Flatworms |
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Describe the typical structural features of cestodes? |
FLATWORMS - Segmented bodies = segments called proglottids or strobila - Head, or scolex = contains suckers, rostellum and hooks for attachment - Newest segments bud from head - Hermaphrodites (only takes one to infect) - No alimentary canal = highly absorptive outer membrane (tegument) |
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Segments of the cestode are also called? |
Proglottids or strobila |
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The head of the cestode is also called? |
SCOLEX |
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A mature tapeworm segment mid-body typically contains _____________, while segments towards tail-end contain ________________. |
* Mid-body segments = reproductive organs & genital pores.
* Tail-end segments = GRAVIDS (EGG PACKETS); drop off into the feces where they will continue to mature, hatch and infect. |
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Describe the Taenia egg. |
- Round, brown egg - RADIALLY STRIATED Egg shell - HEXACANTH (6-hooked) embryo or onchosphere
* Most tapeworm eggs resemble this. |
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Cestode life cycle? |
INDIRECT - IMH (mammal) ingests eggs, which then hatch and larval stage encysts - FH (man/cat/dog) eats the cyst containing head of future tapeworm - Head latches on the SI wall and starts to bud segments - FH contains adult tapeworms & pass eggs in feces. |
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List the various larval stages cestodes experience in the IMH: |
- Metacestode or larval form - Usually in tissues: * Cysticercus * Coenorus * Cysticercoid * Hydatid |
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Family Taeniidae: IMH? FH? Scolex armed or unarmed (hooks)? Pathogenic? |
IMH = mammal - larval stage encysted FH = SI of man, cat, dog SCOLEX = Armed (except in T. saginata = human species) Adults = NON-PATHOGENIC Cystic Larvae = Most Pathology. |
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Cysticercus bovis? |
TAENIA SAGINATA = cystic form that develops in cattle, which serve as the IMH for infection in humans (FH). - Present as small, fluid-filled cysts within cattle containing a single scolex (head). |
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Life cycle of Taenia saginata? |
Eggs ingested by susceptible bovine - Onchopheres released in abomasum & penetrate SI wall - Travels to skeletal muscle & encysts = CYSTICERCUS BOVIS - Meat ingested by human - PPP = 2-3 months before human starts passing eggs |
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Epidemiology of Taenia saginata? |
- Areas of poor sanitation are highly susceptible; using human sludge as fertilizer ('Cysticercosis storm') - Eggs long lived & cattle highly susceptible (30-60%) - Inadequate cooking of meat |
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Diagnosis of taenia saginata? |
- Meat inspection - checking for cysts, particularly in masseter, heart, tongue, intercostals & diaphragm |
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Control of taenia saginata? |
* MEAT INSPECTION: >25 cysts = condemn * Cook meat properly (57C) * Restrict use of human sludge: cultivated fields or no cattle grazing for at least 2 years following * Hygiene and sanitation upheld |
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Taenia solium: IMH? FH? Pathogenic? |
Nastier version of Taenia saginata! IMH: Pig or Human FH: Human Pathogenic? Cystic form (cysticercus cullulosae) is most pathogenic part & may occur in pigs or humans. |
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Life cycle of Taenia solium? |
Similar to T. saginata: Ingested by susceptible pig/human: - Onchopheres released in abomasum & penetrate SI wall - Travels to skeletal muscle & encysts = cysticercus cullulosae (instead of bovis) - Meat ingested by human & adults form - PPP = 2-3 months before human starts passing eggs |
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Human can act as IMH for taenia solium.
True or False? |
TRUE - Eggs are infective for humans & can be auto-infective via reverse peristalsis (move back up stomach, activate and hatch) |
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Pathology of taenia solium? |
Adults = No pathology Cysticerci = PATHOLOGY: - Cysts in CNS or EYE - Major problem in latin america
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Epidemiology of taenia solium? |
Thrives on close association of man and pig! - Perpetuated by unrestricted access of pigs to human waste. - Poor meat inspection - 10% of humans & 40% of pigs are sero-positive in endemic areas of S. America |
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Control of taenia solium? Issues? |
CONTROL: - Mass treatment to kill adult worms in humans! (e.g. albendazole or praziquantel) - Mass treatments of pigs = oxfendazole (kills cysts) - Detection and treatment of carriers - Health education - Meat inspection - Pig corralling (kept in restricted pens away from human sludge) - Vaccination of pigs ISSUES: - Cultural considerations - Costs & long term sustainability of control - Efficacy of vaccines |
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What are the three main taenia species of concern in the UK? |
1. TAENIA MULTICEPS (IMH: Sheep -> FH: Dog) 2. T. HYDATIGENA (IMH: Sheep -> FH: Dog) 3. T. OVIS (IMH: Sheep -> FH: Dog) |
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TAENIA MULTICEPS - IMH? FH? Adult worm length? Pathology? |
IMH: Sheep FH: Dog Adult worm: ~100cm long Pathology: - Coenorus cerebralis = cystic forms in sheep CNS causing "GID" (Ataxia) |
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TAENIA HYDATIGENA - IMH? FH? Adult worm length? Pathology? |
IMH: Sheep FH: Dog Adult worm: ~500cm long (bigger then T. multiceps) Pathology: - Cysticercus tenuicolis = cystic forms in sheep containing single head - Commonly found in abattoir; persistent condemnation of livers |
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TAENIA OVIS - IMH? FH? Adult worm length? Pathology? |
IMH: Sheep FH: Dog Adult worm: ~200 cm long Pathology: - Cysticercus ovis = sheep measles, white spots at PM; relatively common - FIRST RECOMBINANT VACCINE AGAINST HELMINTH PARASITE (T. ovis vaccine) |
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FIRST RECOMBINANT VACCINE AGAINST HELMINTH PARASITE DEVELOPED AGAINST . . ? |
TAENIA OVIS |
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TAENIA TAENIAEFORMIS - IMH? FH? Adult worm length? Pathology? |
IMH: Mouse, rat FH: Cat Worm: ~60 cm long Pathology: - Cysticercus fasciolaris |
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Life cycle of diplyidium caninum? |
Adult worms in SI of dog, cat & man shed gravid segments into feces - Ingested by feces/louse (IMH) - Tiny, solid, cysticercoids form in haemocoel of flea/louse - IMH ingested by dog/cat/man - Flea & cysticercoids digested, larvae pops out and develops into an adult in the SI |
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Describe the head of Diplyidium caninum: |
- Rostellum with hooks at top of head - Suckers located around the periphery of the head |
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Diplyidium caninum - IMH? FH? PPP? |
IMH: Flea larvae & Lice (all stages) FH: Dogs, cats, man PPP: 3 weeks |
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Diagnosis of Diplyidium caninum? |
1. Double genital pores 2. Egg packets * Two main distinctive features from Taenia! 3. Active motile segments 4. Rice grain-shaped segments |
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Diplyidium caninum vs Taenia? Why is it important to distinguish? |
D. Caninum: - Double genital pores - Egg packets - Rice grain-segments - Motile segments - Single genital pore - More block-like segments Important to distinguish, because if you're dealing with a diplyidium caninum you'll have to treat the internal and external parasites (fleas/louse). |
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Cestodes have different morphology and life cycles from nematodes.
True or False? |
TRUE - Cestodes have no L1, L2, etc & are flatworms! |
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With cestodes there is always a final host and an intermediate host (usually containing encysted larvae).
True or false? |
TRUE - Most of the pathology is in the IMH
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Taenia _________ is pathogenic in humans. |
T. SOLIUM |
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Taenia ________ is a source of major economic loss in the UK. |
T. OVIS |
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List the three main echinococcus species in vet med: |
1. Echinococcus granulosus granulosus 2. Echinococcus granulosus equinus 3. Echinococcus mulltilocularis |
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Important horse cestode? |
ANOPLOCEPHALA PERFOLIATA |
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ECHINOCOCCUS GRANULOSUS GRANULOSUS - IMH? FH? Site? Zoonotic? |
E. g. granulosus IMH: Ruminants, pigs & humans FH: Dog & wild canids Site: SI Zoonotic: YES! |
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ECHINOCOCCUS GRANULOSUS EQUINUS - IMH? FH? Site? Zoonotic? |
E. g. equinus IMH: Horse & donkey FH: Dog, red fox Site: SI Zoonotic: No |
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Describe the typical structural features of echinococcus. |
- Very small (~6mm) - Scolex + 3-4 segments - Eggs look similar to Taenia eggs = radial striations around eggshell and 6-hooks |
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Life cycle of echinococcus granulosus granulosus? |
Adults reproducing in SI of dog/wild canids - Gravid segments dropped 1 per weeks - Ingested by IMH (ruminant, pig, human) - Onchosphere released & penetrates SI wall - Hydatid cysts form in IMH liver/lungs (~6 months post ingestion) - Several larvae per cyst! - Cyst ingested by final host, where they hatch and develop into adults in SI - PPP = 40-50 days |
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Echinococcus granulosus granulosus pathology is related to the adult worms, not the cysts.
True or False? |
FALSE - dogs can have thousands of worms with no pathology. - CYSTIC STAGE IS PATHOGENIC |
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Echinococcus granulosus species produce hydatid cysts within their IMH. Where do the cysts more commonly appear in Horses? Cattle? Sheep? |
Horses & Cattle = 90% hyatids in LIVER
Sheep = 70% lung & 25% liver
* Most cysts in cattle are sterile! No protoscoleces inside |
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Protoscoleces within the hydatid cysts bud off from ___________________. |
GERMINAL EPITHELIUM |
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"Hyatid sand" |
What you'd aspirate from a E. granulosus cyst: - Protoscoleces or heads of future tapeworms |
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Diagnosis of Echinococcus granulosus? |
In IMH: - at abattoir = cysts within liver/lungs In FH: - FEC - ELISA Copra-antigen test - Copro-PCR |
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Pathogenesis E. granulosus? |
Mostly well tolerated in IMH, unless cysts forms in unusual place (e.g. CNS) - Most cases detected in abattoir - Non-pathogenic in FH (dogs) * Always of significance in humans! |
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Domestic and sylvatic (cycle in wildlife) epidemiology of echinococcus granulosus? E. g. equinus? |
E. g. granulosus DOMESTIC: - Typically seen near sheep farms where IMH = sheep and FH = dogs SYLVATIC: - Maintained by predation of wild dogs on carrion, livestock, etc
E. g. equinus: - Maintained by feeding hunting dogs on equine viscera. |
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Echinococcus g. granulosus is zoonotic.
True or False? |
TRUE - common in sheep farming areas. - Requires close man-dog contact |
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Control of hyatid disease (E. granulosus)? |
Break the cycle by: - Regular deworming of dogs (praziquantel) - Proper disposal of infected carcasses - Deny access of dogs to abattoirs - Good hygiene |
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Echincoccus multilocularis - IMH? FH? Zoonotic? Distribution? |
IMH: Rodents, man FH: Dog, cat, wild canids Zoonotic? YES! Distribution: Prevalent in Europe |
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Life cycle of Echinococcus multilocularis? |
Adults in SI of dog, cat, wild canids (FH) release gravid segments in feces - Eggs resistant to -50C - Ingested by rodents - Embryo released penetrates SI wall - Passes to liver, via hepatic portal vein & rapidly vesiculates in rodent - IMH ingested by FH and infection proceeds to adults forming and reproducing in SI of FH. - PPP = 4-5 weeks |
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Zoonotic effects of echinococcus multilocularis? |
Causes alveolar echinococcosis in humans - Potentially fatal - If untreated, can have long asymptomatic period (5-15 years) followed by acute clinical signs. - Treatment: liver transplant, section of albendazole! |
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No recent positive cases of echinococcus multilocularis in recent UK survey.
True or False? |
TRUE - due to PET PASSPORT! - Dogs and cats must be treated against E. multilocularis (praziquantel), 24-48 hours prior to returning to UK |
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ANOPLOCEPHALA PERFOLIATA - IMH? FH? Site? Distribution? Pathology? |
IMH: Orbatid forage mites FH: Equine Site: Small & large intestines Distribution: Temperate climates Path: - Ulcerations at site of attachment * Risk of ileo-caecal colic! |
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Describe the structural features of anoplocephala perfoliata? |
Very WIDE, stubby cestode! - Head contains: Suckers & Lappets |
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Life cycle of anoplocephala perfoliata? |
Adults at ileo-caecal junction release eggs in feces - Ingested by forage mite (IMH) - Forms cysticercoid in mite (same as D. caninum) - Infected mite ingested by horse - Attaches to gut wall & starts to bud - PPP = 6-10 weeks |
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Horse with tapeworms are more likely to suffer from colic.
True or False? |
TRUE - 80% of 20 cases of ileal impaction colic were tapeworm associated! |
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Treatment of Anoplacephala perfoliata? |
PZQ +/- Ivermectin |
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Diagnosis of Anoplacephala perfoliata? |
- FEC (Irregular shaped eggs with pyriform apparatus at center) - ELISA - Copra-Ag PCR |
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Echinococcus sp are important zoonotic parasites, particularly _________________ in the UK. |
E. g. granulosus - Humans are infected with cystic stage via ingestion of eggs (via water or food source or contact with infected dog) - Highest level of infection in sheep farming areas. |
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__________________ is an additional cause of colic in horses. |
Anoplacephala perfoliata |
