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VMS 2007 > Parasites of the nervous system > Flashcards

Parasites of the nervous system Flashcards

1
Q

What type of parasite is taenia multiceps?

A

Cestode parasite (tape worm)

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2
Q

What is the definitive host of taenia multiceps?

A

Canids

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3
Q

What disease does taenia multiceps cause?

A

Causes disease coenurosis, aka “gid” or “staggers”, in sheep

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4
Q

Where is taenia multiceps found?

A

Found worldwide but absent from the USA and New Zealand

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5
Q

What is the adult morphology of taenia multiceps?

A
  • Adult worms are 40-100cm in length
  • They have small heads, 0.8mm in diameter
  • also have a double ring of rostellar hooks
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6
Q

What is the pathology of taenia multiceps?

A
  • Cysts (5cm long) are found in the cerebral hemisphere
  • they are found less commonly in the cerebellum or spinal cord
  • As the cyst develops -> damage to brain tissue -> neurological disturbances
  • Cyst causes pressure atrophy -> perforation of the skull
  • Cysts in the spinal cord -> paresis of the hindlimb
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7
Q

What are the clinical signs of acute coenurosis?

A
  • sheep graze on heavily contaminate pasture
  • migration of larvae through the brain causing neurological dysfunction
  • clinical signs appear 10 days after infection
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8
Q

When does death occur from acute coenurosis?

A

Death occurs 3-5 days from the onset of neurological signs

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9
Q

What is the pathology of acute coenurosis?

A

acute meningoencephalitis and pale yellow tracts (necrotic tissue) on the brain surface

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10
Q

When does chronic coenurosis occur?

A

3-6 months post infection in sheep 6-18 months of age

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11
Q

What does a chronic coenurosis lesion look like?

A

progressive focal lesion of the brain
presentation depends on the cyst location and size

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12
Q

What are the clinical signs of chronic coenurosis?

A

Compulsive Circling behaviour, head pressing and depression
Visual defects, stumbling/ uncoordinated movements, postural defects, animal may also develop anorexia and weight loss
* sheep will circle towards the side of superficial cysts and away from deeply-sited cysts

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13
Q

What is the definitive host of T.multiceps?

A

Dogs, can diagnose by finding tapeworm segments in perianal area or proglottids/ eggs in faeces

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14
Q

How could you treat the intermediate host of T.multiceps?

A
  • Surgery to remove the cyst
  • Slaughter sheep fit for market, and euthanise any others
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15
Q

How could you control T.multiceps?

A
  • Regular anthelmintic treatment of working dogs
  • Correct disposal of sheep carcasses
  • Vaccine based on recombinant proteins of T.multiceps
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16
Q

How can humans become infected with Coenurosis?

A

accidental ingestion of parasite eggs, contaminating food or water

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17
Q

When do coenurosis cysts develop?

in humans

A

they develop over 90 days

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18
Q

What are the neurological symptoms of coenurosis in humans?

A
  • headaches, seizures, hemiparesis, and hydrocephalus
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19
Q

What is the adult morphology of thelazia callipaeda?

A
  • Thin/ yellowish worms
  • 1-2cm long
  • round worms (nematodes)

green picture on histo

20
Q

What is the pathogenesis of thalezia?

A

Lesions and damage are due to serrated cuticle of the worm and movement of active young adults
* causes lachrymation and conjunctivitis
* photophobia in cattle

21
Q

What do heavy thalezia infections look like?

A

cornea is cloudy and ulcerated, swollen eye

flies will cluster around the eyes

22
Q

What may a thalezia infecton predispose to?

A

secondary bacterial infection

23
Q

What are the two ways you may diagnose thalezia?

A
  • Conjunctivitis in the season of fly activity
  • Observation of worms on the conjunctival surface/ in the conjunctival sac
24
Q

How may you treat thalezia?

A
  • Anthelmintics
  • Mechanical removal with forceps (horses and dogs)
25
Q

How long can the thalezia parasite survive in the eye?

A

The parasite can survive in the eye or several years, but only the young adult is pathogenic -> symptomless reservoir

26
Q

What is sarcocystitis neurona?

A
  • Protozoan parasite
  • causes equine protozoal myeloencephalitis (EPM)

found in the americas

27
Q

Where is Sarcocystitis neurona found geographically?

A

the Americas

28
Q

How can horses become infected via sarcocystitis neurona?

A

ingestion of food or water contaminated with opossum faeces

29
Q

What are the risk factors of sarcocystitis neurona?

A
  • Seasonality (more common in autumn)
  • Presence of opossums in wooded areas
  • Stress
  • racehorses/ show horses
30
Q

What are the clinical signs of sarcocystitis neurona?

pathologically

A

acute or chronic multifocal neurological disease

31
Q

What are the clinical signs of sarcocystitis neurona?

A
  • Dysphagia
  • abnormal upper airway function
  • unusual lameness
  • seizures
  • head-tilt
  • facial nerve paralysis

in vital signs- animal appears alert and vital signs are normal

32
Q

How could you treat sarcocystitis neurona?

A

Medical and supportive treatment as neccesary

33
Q

How can you control sarcocystitis neurona?

A
  • Decrease stress
  • decrease exposure to opossum faeces
  • intermittent drug treatment
34
Q

What are the clinical signs of canine neosporosis?

A

fatal progressive ascending hindleg paralysis
* lesions in the brain, spinal cord, nerve roots, skeletal muscle
* more severe in transplacentally infected puppies

35
Q

Where are canine neosporosis lesions most commonly found?

A
  • Brain, Spinal Cord, nerve roots, skeletal muscle
36
Q

What is the lifecycle of taenia multiceps?

A
  • Eggs are in faeces and then pass onto the environment
  • Embryonated eggs then pass onto/ are ingested by the intermediate host
  • Oncospheres hatch and penetrate the intestinal wall, circulate to tissue
  • Oncospheres develop into coenuri in the tissue of the intermediate host
  • Canids are infected by ingesting the intermediate host
  • Scolex attaches to the intestine, they become adults in the small intestine
  • embryonated eggs are ingested by a human host
37
Q

How would you diagnose Taenia in the intermediate host?

A
  • Clinical signs, differentials, listeriosis, louping-ill, sarcocystosis, polioencephalomalacia
  • CSF collection and analysis
  • local softening of the frontal bones
  • Ultrasound
38
Q

How would you diagnose Taenia in the definitive host?

A
  • Diagnosis in dogs-> presence of tapeworm segments in the perianal area or proglottids/ eggs in faeces
39
Q

How do humans become infected with coenurosis?

A

Accidental ingestion of parasite eggs
* Cysts develop over 90 days

40
Q

Name 4 eye worms

A
  • Thelazia rhodesi
  • Thelazia lacrymalis
  • Thelazia callipaeda
  • Oxyspura mansoni
41
Q

What is the lifecycle of Thelazia?

Muscid fly

A
  • Adults shed larvae by oviviviparity in the conjunctiva of the definitive host
  • first-stage larvae are ingested by the insect intermediate host as it feeds on tears of teh definitive host
  • L1-> L3 follicles in summer months
  • Larvae develop into L3 larvae in the intermediate host
  • L3 migrate to fly mouthparts
  • Cattle horses and dogs serve as primary definitive hosts, they become adults in the conjunctival sac
  • Humans become incidental hosts
42
Q

What is the epidemiology of thalasezia?

A

Infections occur seasonally, linked to periods of maximum fly activity
Larvae can survive in fly pupae overwinter
[arasite survives in the eye for severa; years but only the young adult is pathogenic -> symptomless reservoir

43
Q

What is the lifecycle of sarcocystitis?

A
  • Horse ingests a sporocyst
  • Horse acts as an abberant host
  • Intermediate host -> cat, skunk, raccoon, sea-otter
44
Q

What is the transmission of sarcocystitis?

A
  • Horses are accidental intermediate hosts
  • infected through ingestion of food and water contaminated with opossum faeces
  • no horizontal transmission between horses
  • vertical transmission is very uncommon
  • not all infected horses develop disease
  • mechanism of pathogenesis is poorly understood
45
Q

What is the antemortem diagnosis for sarcocystitis?

A
  • Clinical signs
  • Neurological signs
  • Confirm using immunodiagnostic testing
  • rule out other potential causes

VMS 2007 (28 decks)

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