Parasitology Exam 3: Microfilariae Flashcards

1
Q

What are microfilaria?

A

Roundworms (nematodes) that infect blood/tissue in humans

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2
Q

How are microfilaria transmitted?

A

Blood-sucking arthropod vector (mosquito, midge, fly)

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3
Q

How are microfilaria identified?

A

Morphology of microfilaria, define circadian rhythm, and location within human host

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4
Q

What are the blood and tissue microfilaria that infect humans?

A

W. bancrofti
B. malayi
Loa loa
O. volvulus
Mansonella spp.
Dirofilaria spp.

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5
Q

How is Wuchereria bancrofti transmitted?

A

Via mosquito bite from Anopheles, Aedes, or Culex fatigans

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6
Q

Morphology of Wuchereria bancrofti adult worm

A

Has a sheath
NO nuclei present in end of tail

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7
Q

What is the most commonly identified species of filarial worms that infects humans?

A

W. bancrofti

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8
Q

What disease does W. bancrofti cause?

A

Bancroftian filariasis and elephantiasis including hydrocele, chyluria, tropical pulmonary eosinophilia

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9
Q

What is hydrocele?

A

Fluid-filled sac within the scrotum

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10
Q

What is chyluria?

A

Milky white urine due to obstruction of lymphatic vessels

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11
Q

What is an endosymbiont?

A

Bacteria (Wolbachia) required for larval development of certain microfilaria (W. bancrofti, Brugia spp., and Onchocerca volvulus)

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12
Q

Wolbachi

A

Endosymbiont, obligate intracellular organism

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13
Q

What is Knott concentration?

A

Used to recover small numbers of microfilaria in the blood, centrifugation is used to concentrate organisms onto a slide

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14
Q

Describe the morphology of Brugia malayi

A

Has a sheath that stains BRIGHT PINK
2 terminal nuclei in tail

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15
Q

How is Brugia malayi transmitted?

A

Mosquito (Anopheles or Mansonia)

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16
Q

Which microfilaria is distributed throughout the Far East?

A

Brugia malayi

17
Q

Differentiate between the 2 periodic forms of Brugia malayi

A

Nocturnal form - located near rice fields (most common)

Nonperiodic form - located near swampy forests

18
Q

Describe the disease presentation of Brugia malayi

A

Essentially same as W. bancrofti (Elephantiasis, lymphadema)
EXCEPT no hydrocele or chyluria

19
Q

Lab ID of brugia malayi?

A

ID of microfilariae in blood

20
Q

What is another name for Loa loa?

A

The eye worm

21
Q

What is the vector of Loa loa?

A

Deer fly (Chrysops spp)

22
Q

What is the diurnal periodicity of loa loa?

A

Peak numbers of worms in blood between 12pm and 2pm

23
Q

What is the disease presentation of Loa loa?

A

Calabar swellings
- Localized area of angioedema in response to production of parasitic metabolic products
Involves swelling of the eye area

24
Q

Describe morphology of Loa loa

A

Have a sheath (unstained)
Nuclei extend through the tip of the tail

25
Q

Describe the morphology of Onchocerca volvulus

A

NO sheath!
NO nuclei into tip of tail!

26
Q

Vector of Onchocerca volvulus

A

Black fly (Simulium spp)

27
Q

Disease presentation of Onchocerca volvulus

A

River Blindness
- Skin infections
- Lymph node infections
- Eye infections that can lead to blindness

28
Q

Lab ID of onchocerca volvulus

A

ID of microfiliarie in tissue

29
Q

What is the vector/transmissioon of Mansonella spp?

A

Biting midges (Culicoides)

30
Q

Where are the different species of Mansonella spp found?
M. streptocerca
M. perstans
M. ozzardi

A

M. streptocerca: skin
M. perstans: pericardial, pleural, and peritoneal cavities
M. ozzardi: unknown

31
Q

Lab ID of Mansonella spp?

A

ID of microfilaria in blood/body fluids

32
Q

Morphology of M. streptocerca

A

NO sheath
Nuclei extend to tip of tail
Shepherd’s crook

33
Q

Morphology of M. perstans

A

NO sheath
Nuclei extend to tip of tail

34
Q

Morphology of M. ozzardi

A

NO sheath
Nuclei do NOT extend to tip of tail

35
Q

What is the main organism of Dirofilaria spp and what does it cause?

A

D. immitis
Causes heartworm in dogs and wild canids

36
Q

Definitive host of D. immitis

A

Dogs and wild canids

37
Q

Dead-end host of D. immitis

A

Humans

38
Q

Lab ID of Dirofilaria immitis

A

Examination of inflammatory lung tissue or skin nodule
Worm’s cuticle contains chitin which is visualized with calcofluor white stain