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OD2 (S1&2) > MIIM - Parasites Causing Ocular Infections - Week 10 > Flashcards

MIIM - Parasites Causing Ocular Infections - Week 10 Flashcards

1
Q

In what 5 situations would you suspect parasites in the eye/appendages? Explain each if applicable (6).

A

Infection in contact lens users
-not responding to antibiotics
-poor/doubtful CL hygiene

Immunocompromised patients
-malignancy, HIV, steroids etc

Returning traveller/migrant from a developing country
-insect bites
-swam in a river/lake
-consumed exotic raw/undercooked food

zoonosis: contact with animals/faeces
-poor/doubtful hygiene

Sexual partner has similar lesions (including around the genitals)

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2
Q

Define parasitism.

A

A living organism living in/on another living organism, gaining benefit at the expense of the host.

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3
Q

Define commensalism.

A

Living in/on a host with no harm to the host.

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4
Q

Define symbiosis.

A

Two mutual orgnaisms gaining benefit from one another, where both are dependent on one another.

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5
Q

Are parasites necessarily micro-organisms?

A

No, they can be in the animal kingdom as well.

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6
Q

Briefly describe the classification of parasites, including uni/multicellular forms (3).

A

Unicellular - protozoa
Multicellular - metazoa
-helminths (worms)
-arthropods (insects)

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7
Q

Define definitive host.

A

Carrier of adult or sexual stage of the parasite

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8
Q

Define intermediate host.

A

Carrier of all or part of the larval or asexual stage of the parasite

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9
Q

Can there be multiple intermediate hosts or is the limit just one?

A

Sometimes there are two

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10
Q

Define incidental/accidental host.

A

Host is not necessarily for the parasite’s survival

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11
Q

Define reservoir/natural host.

A

Animals which normally harbour the parasite and are part of its life-cycle

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12
Q

Define the two types of vectors.

A

Biological - in which part of the life cycle is passed
Mechanical - life cycle is not passed

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13
Q

What are the usual vectors for parasites?

A

Arthropods

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14
Q

What is the taxonomy of acanthamoeba?

A

Unicellular protozoa - a soil amoeba.

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15
Q

What structure of the eye does acanthamoeba infect?

A

The cornea

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16
Q

How is acanthamoeba transmitted?

A

Poor contact lens hygiene

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17
Q

Name 5 symptoms of an acanthamoeba infection.

A

Irritation
Pain
Photophobia
Blurry vision (leading to blindness)
Conjunctivitis

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18
Q

Name two secondary complications of an acanthamoeba infection.

A

Ulceration
Bacterial infection

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19
Q

What are two ways to diagnose an acanthamoeba infection (laboratory)?

A

Demo of amoeba in corneal scrapings
Culture on non-nutrient agar

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20
Q

In what two ways can an acanthamoeba infection be treated (3)?

A

Surgical debridement ± keratoplasty
Complex medical topical therapy

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21
Q

Do all amoeba cause keratitis?

A

No

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22
Q

Do all amoeba infection require extensive surgical care?

A

No, some just require changing lens and paying more attention to CL hygiene.

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23
Q

What is the taxonomy of toxoplasma gondii?

A

A small intracellular protozoa

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24
Q

How is toxoplasma gondii transmitted (2)?

A

Contact with cats, especially kittens
Eating undercooked meat

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25
Q

What is the definitive host (and possible other intermediate hosts) of toxoplasma gondii?

A

Cats/kittens the definitive host
Many species of animals that humans eat are intermediates

26
Q

What are two clinical presentations of congenitcal toxoplasma gondii?

A

Severe foetal disease
Chorioretinitis (late in life)

27
Q

What is a clinical presentation of acquired toxoplasma gondii in an immunocompetent patient? What does it depend on?

A

Usually asymptomatic and depends on the position.

28
Q

Do toxoplasma gondii cysts persist for life?

A

They might

29
Q

Describe 5 ways to diagnose toxoplasma gondii and describe it if possible, whether it is in use or not, and name the main way it is done.

A

Serology - rise in titr of IgG and IgM
Histopathology of tissue
Culture - tedious and not done
PCR - tissue/vitreous - mainstay
Foetal infection - PCR on amniotic fluid/foetal blood

30
Q

How is congenital toxoplasma gondii infection treated (2)?

A

Termination (especially if 1st or 2nd trimester)
Spiramycin to the mother (difficult to get)

31
Q

How is a reactivated toxoplasma gondii infection treated (3)?

A

Pyrimethamine + sulphadiazine + prednisolone

32
Q

If you suspect an infection to be toxoplasma gondii, and the patient presents with nystagmus, what does this suggest?

A

It may be congenital

33
Q

What is the scientific name for pig tape worm?

A

Taenia solium

34
Q

How is taenia solium transmitted?

A

Ingestion of eggs shed by a human tapeworm carrier

35
Q

How do individuals infected with taenia solium present? Comment on the state of their eyes, and name two conditions they might have.

A

Usually present in skeletal muscles with no symptoms
Eyes are rarely involed
May present with a scotoma, space occupying lesion, or cyst

36
Q

In what two ways can taenia solium be diagnosed?

A

Radiology and serology

37
Q

How is a taenia solium infection treated and what does it depend on?

A

Treatment is either surgical and/or with praziquantel or albendazole + steroids
It depends on the location of the lesion

38
Q

List 5 regions of the eye that ocular cysticercosis can occur.

A

Orbital tissue
Subconjunctiva
Anterior chamber
Subretinal space
Vitreous

39
Q

What is the scientific name for dog round worm?

A

Toxocara canis

40
Q

How is toxocara canis transmitted?

A

Accidental infection by larvae entering through the skin

41
Q

What does the severity of a toxocara canis infection depend on?

A

The site where it deposits

42
Q

What are two clinical presentations of a toxocara canis infection?

A

Retino-choroiditis
Granuloma resembling a tumour

43
Q

How can a toxocara canis infection be diagnosed?

A

Serology

44
Q

Is there a high incidence of filarial worm infection in australia? Explain.

A

No, due to the heart worm control program

45
Q

What is phthirus pubis and what 4 regions of the body can they infest?

A

An arthropod that can infect pubic, axillary, truncal hair, and eyelashes.

46
Q

How is phthirus pubis transmitted.

A

Person to person by direct contact

47
Q

Is a phthirus pubis an STI?

A

Yesd

48
Q

List two symptoms of phthirus pubis.

A

Pruritis
Macules/papules with excoriation

49
Q

How can phthirus pubis be diagnosed?

A

Demonstration of lice or eggs (stuck to hair)

50
Q

Name three treatment options for phthirus pubis.

A

1% permethrin to all hair-bearing areas except the eyes
Eyelashes - remove with forceps
Clothes and bed linen - hot wash

51
Q

Give thetwo examples of eyelash mites.

A

Demodex folliculorum
Demodex brevis

52
Q

How are eyelash mites transmitted.

A

Person to person contact

53
Q

What four conditions might someone with eyelash mites present with?

A

Folliculitis
Blepharitis
Blepharo-conjunctivitis
Corneal lesions

54
Q

How can eyelash mites be diagnosed.

A

Demonstration of mites in skin scrapings or a biopsy

55
Q

List three treatment options for eyelash mites.

A

Topical tea tree oil/ointment for skin only
Ivemrectin - single dose
Oral doxycycline for secondary bacteria (symbionts)

56
Q

What is the scientific name of an itch mite?

A

Sarcoptes scabei

57
Q

How are itch mites transmitted (2).

A

Person to person - bad hygiene
Sexual contact

58
Q

List three symptoms of an itch mite infestation.

A

Severe pruritis
Erythematous papules
Crusted nodules/plaques

59
Q

How can itch mites be diagnosed?

A

Demonstration of mites, eggs, or faecal pellets

60
Q

Name four treatment options for itch mites.

A

Topical 5% permethrin from head to toe except the face
Ivermectin orally
Treat close contacts
Hot wash, including clothes and bed linen

OD2 (S1&2) (174 decks)

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