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OD2 Semester 1 - Applied Clinical Training > M: Parasitic Infections of the Eye - Week 10 > Flashcards

M: Parasitic Infections of the Eye - Week 10 Flashcards

1
Q

Name 5 situations where you might suspect parasites in the eye/appendages

A
  • infections in contact lens uses: that aren’t responding to antibiotics
  • immunocompromised person
  • returned traveler/migrant from developing country
  • zoonosis: contact with animals (esp. faeces)
  • sexual partner has similar/other genital lesions
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2
Q

How might a travelling person acquire parasites? Name 3 ways

A
  • bitten by insects
  • swam in rivers/lakes
  • consumed ‘exotic’/raw/undercooked food (frogs, snakes, seafood)
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3
Q

Define parasitism

A

a living organism (parasite) living on/in another living organism (host), causing harm to the host

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4
Q

Define commensalism

A

an association between two organisms in which one benefits and the other derives neither benefit nor harm.

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5
Q

Define symbiosis

A

interaction between two different organisms living in close physical association, typically to the advantage of both.

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6
Q

What kingdom to parasites belong to?

A

Animal kingdom

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7
Q

How can parasites be broadly classified?

A

As unicellular or multicellular

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8
Q

What are unicellular parasites called? What are multicellular parasites called?

A

unicellular = Protozoa. multicellular = Metazoa

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9
Q

What 2 categories can we classify metazoa?

A
  • Helminths (worms)

- Arthopods (insects)

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10
Q

In what 5 categories can we classify protozoa?

A
  • Amoeba
  • Flagellates
  • Cilliates
  • Sporozoa
  • Microsporidia
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11
Q

In what 2 broad categories can we classify helminths?

A
  • Platyhelminths (flat worms)

- Nematohelminths (round worms) (i.e. nematodes)

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12
Q

In what 2 categories can we classify platyhelminths?

A
  • Trematodes (leaf shaped)

- Cestodes (tape shaped)

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13
Q 
Define the following:
A: Definitive host
B: Intermediate host
C: Incidental/Accidental host
D: Reservoir/Natural host
A

A: carries adult or sexual stage of parasite
B: carries all or part of larval or asexual stage of parasite. Sometimes,2 intermediate hosts
C: host is not necessary for parasite’s survival. In fact it is a ‘dead end’ for parasite
D: other animals which normally harbour the parasite and are part of life cycle

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14
Q

What is a Vector? What forms can it be in? (2)

A

A vector is one of two hosts. Usually an arthropod.
it may be:
- biological (in which part of life cycle is passed), or
- mechanical (life cycle not passed)

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15
Q

In what 2 categories can we classify Arthropods (in the eye)?

A
  • Ectoparasites

- Vectors

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16
Q

Name 4 Ectoparasites (that can colonise the eye). And name the conditions they are associated with (4)

A
  • Itch mite (scabies)
  • Mite (demodex)
  • Pubic lice (“crabs”)
  • Fly larvae (ophthalmomylasis)
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17
Q

Name 5 vectors. And name the parasites they transmit [in brackets] (5)

A
  • Sandflies (leishmania)
  • Tse-tsefly (trypanasome)
  • Deerfly (Loa Loa)
  • Blackfly (onchocerca)
  • Fleas/ticks/mosquito (filarial worms)
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18
Q

List 4 ways a parasitic infection of the lids can present

A
  • swelling
  • cysts
  • distorted eyelids
  • crusted lesions
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19
Q

List 1 way a parasitic infection of the following areas present:

  • cornea
  • conjunctiva
  • lacrimal gland
  • optic nerve
  • retina/choroid
A
  • keratitis
  • conjunctivitis
  • davryocystitis
  • neuritis
  • retinoscope-choroiditis
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20
Q

List 2 ways a parasitic infection of the orbit can present

A
  • cyst

- nodule

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21
Q

Name 6 parasites that can affect the eyelid

A
  • Leishmania
  • Taenia cysticercosis
  • Spirometra
  • Pubic lice (‘crabs’)
  • Sarcoptes scabei
  • Demodex

(also - ‘bot’ fly)

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22
Q

Name 4 parasites that can affect the cornea

A
  • acanthamoeba
  • microsporidia
  • leishmania
  • trypanosoma
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23
Q

Name 5 parasites that can affect the conjunctiva

A
  • microsporidia
  • leishmania
  • ‘bot’ fly
  • loa loa
  • animal filarial worms
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24
Q

Name 2 parasites that can affect the lacrimal gland

A
  • Schistosoma

- Cysticercosis

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25
Q

Name 1 parasite that can affect the optic nerve

A
  • gnathostoma
26
Q

Name 5 parasites that can affect the retina/choroid

A
  • toxoplasma
  • toxocara
  • angiostrongylus
  • onchocerca
  • pneumocystis
27
Q

Name 3 parasites that can affect the orbit

A
  • taenia cysticercosis
  • hydatid cyst
  • trichenella
28
Q

For Acanthamoeba species of parasite, describe the following:
A: Describe it. What does it infect?
B: Transmission
C: Diagnosis (2)

A 
A: a soil amoeba - infects cornea
B: contamination due to poor lens hygeine
C: 
- demo of amoeba in corneal scrapings
- culture on non-nutrient agar
29
Q

For Acanthamoeba species of parasite, describe the following:
- list 4 symptoms

A
  1. irritation of eye, pain, photophobia
  2. blurring of vision – blindness
  3. conjunctivitis
  4. complications like ulceration, bacterial infection
30
Q

For Acanthamoeba species of parasite, describe the following:
- list treatment options (2)

A
  1. surgical debridement with/without keratoplasty (surgery if severe)
  2. complex medical topical therapy
31
Q

How easily can we get rid of acanthamoeba?

A

Very difficult to get rid of. The longer you wait, the more difficult it is to treat

32
Q

Name 2 other soil amoeba we can encounter as contaminants. How do we differentiate these from acanthamoeba? (2)

A
  • calpoda sp., and hartmanella sp.
    Diagnosis:
  • demo of amoeba from CL or CL-case or fluid (differentiated on morphology)
  • PCR may be available in some reference labs
33
Q

How do we manage the 2 other soil amoeba that we can encounter as contaminants? (2)

A
  • nil treatment for patient (i.e. no treatment)

- change lens, attention to cleaning

34
Q

For Toxoplasma gondii, describe the following:
A: describe it.
B: Transmission (2)

A

A: a small intracellular protozoa
B:
- contact with cats (esp. kittens) - definitive host
- eating undercooked meat (many species of animals act as intermediate hosts)

35
Q

For Toxoplasma gondii, describe the following:

A: List the 2 clinical presentations and explain them

A
  1. congenital: severe fetal disease, chorioretinitis

2. acquired: usually asymptomatic in the eye of immunocompetent people. Can reactivate if immunocompromised

36
Q

Which presentation of toxoplasma gondii infection is more common?

A

acquired

37
Q

How long may cysts last in immunocompetent people with toxoplasma gondii infection?

A

cysts may persist for life

38
Q

What is the primary source of infection of toxoplasma gondii in people who are immunocompromised?

A

transplant

39
Q

What proportion of the australian population is infected with toxoplasma gondii?

A

30-50%

40
Q

For Toxoplasma gondii, describe the following:

- list 5 means of diagnosis

A
  1. serology: demo of antibodies in serum (expect rise in titre of IgG and IgM)
  2. histopathology of tissue
  3. culture: tedious, not routine
  4. PCR: tissue or vitreous
  5. if foetal infection: PCR on amniotic fluid/foetal blood
41
Q

What is the main diagnostic test used for toxoplasma gondii?

A

PCR

42
Q

For Toxoplasma gondii, describe the following:

- list treatment options (3)

A

For foetal infection:
- termination of fetus (esp. if 1 or 2 trimesters)
- spiramycin to mother (difficult to get)
For reactivated disease:
- pyrimethamine + sulfadiazine + prednisolone

43
Q

In regards to Taenia solium, describe the following:
A: describe the parasite
B: transmission
C: diagnosis (2)

A

A: pig tape worm
B: ingestion of eggs shed by human tapeworm carrier
C: a combination of radiology + serology. Also FNA for histopathology or antigen detection

44
Q

In regards to Taenia solium, describe the following:

- treatment (2)

A

depending on location of lesion, treatment is either surgical and/or treatment with praziquantel or albendazole + steroids

45
Q

In regards to Taenia solium, describe the following:

- clinical presentation (3)

A
  • usually in skeletal muscles with no symptoms

- eyes rarely involved: if involved - scotoma, or space occupying lesion (SOL) or cyst

46
Q

What might you see on a scan of the orbital tissues in a person with ocular cysticercosis?

A

White spots, which are ocular cysts. The more white spots the more severe it is

47
Q

In regards to Toxocara canis, describe the following:
A: describe the parasite
B: transmission
C: diagnosis (2)

A

A: a dog round worm
B: accidental infection by larvae entering through skin and deposit in CNS or eye or other tissue
C: serology or FNA for histopath or antigen detection

48
Q

In regards to Toxocara canis, describe the following:

- clinical presentation (3)

A
  • severity depends on site
  • retino-choroiditis (ocular larva migrans) – nastiest form
  • granuloma resembling tumour
49
Q

In regards to Toxocara canis, describe the following:

- treatment (2)

A

depending on location of lesion, treatment is either conservative/symptomatic. If near the macula, treatment with anti-parasitic drugs + steroids is required

50
Q

Name the 2 most common filarial worm of canids

A
  • Dirofilaria immitis (most common)

- Acanthocheilonema reconditum

51
Q

Name 1 way that ocular larva migrans can present

A

diffuse unilateral subacute neuroretiniits

52
Q

How common are accidental infections in humans? Other animals?

A

uncommon in humans. More common in other animals

53
Q

In regards to Phthirus pubis, describe the following:
A: describe the parasite
B: transmission
C: diagnosis

A

A: an arthropod - infests pubic, axillary, truncal hair and eyelashes
B: person to person by direct physical contact (STI)
C: demonstration of lice or eggs (stuck to hair)

54
Q

In regards to Phthirus pubis, describe the following:
D: list 2 symptoms
E: list 3 treatment options

A

D: pruritis, macules/papules with excoriation
E:
- 1% permethrin to all hair bearing areas (except eyes)
- eyelashes: remove with forceps
- clothes, bed linen: hot wash

55
Q

In regards to Demodex folliculorum or D.brevis, describe the following:
A: describe the parasite
B: transmission
C: diagnosis

A

A: an arthropod (eyelash mite)
B: person to person, autoinfection: numbers increase with age - infects skin (mainly face) and eyelashes
C: demo of mite in skin scrapings or biopsy

56
Q

In regards to Demodex folliculorum or D.brevis, describe the following:
- list 4 clinical presentations

A
  • folliculitis
  • blepharitis (anterior or posterior)
  • blepharo-conjunctivitis
  • corneal lesions
57
Q

In regards to Demodex folliculorum or D.brevis, describe the following:
- treatment options (3)

A
  • topical teatree oil/ointment (for skin only)
  • ivermectin single dose (12ug)
  • Oral doxcycyclin for 2ndary bacteria (symbiotic/infection)
58
Q

In what age group does demodex folliculorum or D.brevis usually occur?

A

Usually in older people

59
Q

In regards to Sarcoptes scabei, describe the following:
A: describe the parasite
B: transmission (2)
C: diagnosis (3)

A

A: an arthropod (itch mite) - infects skin
B: person to person (poor hygeine) or by sexual contact
C: demo of mite, eggs or faecal pellets

60
Q

In regards to Sarcoptes scabei, describe the following:

D: list symptoms (3)

A
  • severe pruritis
  • erythematous papules
  • crusted nodules and plaques
61
Q

In regards to Sarcoptes scabei, describe the following:

E: treatment (4)

A
  • topical 5% permethrin from head to sole, repeat (not on face or eyes)
  • Ivermectin is to be taken orally
  • also treat close contacts and
  • hot wash clothes and bed linen

OD2 Semester 1 - Applied Clinical Training (47 decks)

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