Parasitology Exam 3: Microfilariae

Question 1

What are microfilaria?

Answer 1

Roundworms (nematodes) that infect blood/tissue in humans

Question 2

How are microfilaria transmitted?

Answer 2

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

Question 3

How are microfilaria identified?

Answer 3

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

Question 4

What are the blood and tissue microfilaria that infect humans?

Answer 4

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

Question 5

How is Wuchereria bancrofti transmitted?

Answer 5

Via mosquito bite from Anopheles, Aedes, or Culex fatigans

Question 6

Morphology of Wuchereria bancrofti adult worm

Answer 6

Has a sheath
NO nuclei present in end of tail

Question 7

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

Answer 7

W. bancrofti

Question 8

What disease does W. bancrofti cause?

Answer 8

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

Question 9

What is hydrocele?

Answer 9

Fluid-filled sac within the scrotum

Question 10

What is chyluria?

Answer 10

Milky white urine due to obstruction of lymphatic vessels

Question 11

What is an endosymbiont?

Answer 11

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

Question 12

Wolbachi

Answer 12

Endosymbiont, obligate intracellular organism

Question 13

What is Knott concentration?

Answer 13

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

Question 14

Describe the morphology of Brugia malayi

Answer 14

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

Question 15

How is Brugia malayi transmitted?

Answer 15

Mosquito (Anopheles or Mansonia)

Question 16

Which microfilaria is distributed throughout the Far East?

Answer 16

Brugia malayi

Question 17

Differentiate between the 2 periodic forms of Brugia malayi

Answer 17

Nocturnal form - located near rice fields (most common)

Nonperiodic form - located near swampy forests

Question 18

Describe the disease presentation of Brugia malayi

Answer 18

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

Question 19

Lab ID of brugia malayi?

Answer 19

ID of microfilariae in blood

Question 20

What is another name for Loa loa?

Answer 20

The eye worm

Question 21

What is the vector of Loa loa?

Answer 21

Deer fly (Chrysops spp)

Question 22

What is the diurnal periodicity of loa loa?

Answer 22

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

Question 23

What is the disease presentation of Loa loa?

Answer 23

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

Question 24

Describe morphology of Loa loa

Answer 24

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

Question 25

Describe the morphology of Onchocerca volvulus

Answer 25

NO sheath! NO nuclei into tip of tail!

Question 26

Vector of Onchocerca volvulus

Answer 26

Black fly (Simulium spp)

Question 27

Disease presentation of Onchocerca volvulus

Answer 27

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

Question 28

Lab ID of onchocerca volvulus

Answer 28

ID of microfiliarie in tissue

Question 29

What is the vector/transmissioon of Mansonella spp?

Answer 29

Biting midges (Culicoides)

Question 30

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

Answer 30

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

Question 31

Lab ID of Mansonella spp?

Answer 31

ID of microfilaria in blood/body fluids

Question 32

Morphology of M. streptocerca

Answer 32

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

Question 33

Morphology of M. perstans

Answer 33

NO sheath Nuclei extend to tip of tail

Question 34

Morphology of M. ozzardi

Answer 34

NO sheath Nuclei do NOT extend to tip of tail

Question 35

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

Answer 35

D. immitis Causes heartworm in dogs and wild canids

Question 36

Definitive host of D. immitis

Answer 36

Dogs and wild canids

Question 37

Dead-end host of D. immitis

Answer 37

Humans

Question 38

Lab ID of Dirofilaria immitis

Answer 38

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