Blood/Tissue Nematodes

Question 1

Blood and tissue nematodes are referred to as:

Answer 1

Filarial worms

Question 2

Females are viviparous, meaning:

Answer 2

they produce elongated and worm-like embryos called microfilariae

Question 3

Filarial worms inhabiting blood are ______

Answer 3

Sheathed

Meaning they retain egg shell as a membrane

Question 4

Tissue-dwelling filarial worms are ________

Answer 4

unsheathed

They loose their shell during development

Question 5

Wucheria bancfrofti causes

Answer 5

Bancrofti filariasis or lymphatic filariasis or elephantiasis

Question 6

Wucheria bancfrofti adults live in:

Answer 6

The major lymphatic ducts of humans

Question 7

In W. bancrofti females produce:

Answer 7

Sheathed microfilariae which will circulate in the blood

Question 8

Why are microfilariae found in the blood?

Answer 8

Arthropods take a blood meal which further perpetuates spp.

Question 9

Are there nuclei in the tail of W. bancrofti?

Answer 9

No

Question 10

Periodicity in W. bancrofti microfilariae

Answer 10

Only found in peripheral blood at night, when vector takes a blood meal

also depends on the circadian rhythm of host

Question 11

primary vectors of Wuchereria

Answer 11

Culex, Anopheles, Aedes, and Mansonia

Question 12

During the day, the bacrofti microfilariae are concentrated in:

Answer 12

blood vessels of the deep tissues of the body

Question 13

physiological factors associated with sleeping _______________________ which trigger the behavior of _________

Answer 13

decreased body temperature and oxygen tension, increased carbon dioxide, lower adrenal activity

microfilarae

Question 14

In W. bancrofti, once ingested by mosquitoes:

Answer 14

lose their sheath in insects stomach

penetrate gut and enter thoracic muscles

Sausage stage develops which has most of the organ systems present

Filarifrom stage develops and travels ot mosquitoes proboscis where they are infective to definitive host

Question 15

In W. bancrofti, when the mosquito feeds on human:

Answer 15

The filariform larvae escape

They migrate through peripheral lymphatics

They reach larger lymphatics where they settle, mature and mate producing microfilariae

Question 16

3 phases of W. bancrofti pathogenesis:

Answer 16

incubation (asymptomatic), acute inflammatory phase, and the obstructive phase

Question 17

Incubation phase in W. bancrofti

Answer 17

the time between infection and the appearance of microfilarae in the blood. It is largely symptomless, but there may be mild fever and general weakness

Question 18

Acute inflammatory phase in W. bancrofti

Answer 18

female worms attain maturity and start releasing microfilarae

females block lymph vessels and glands, resulting in edema

Intense lymphatic inflammation mostly affects the lower half of the body

chills, fever, and toxemia

Question 19

Obstructive phase in W. bancrofti

Answer 19

lymph varices
chyluria (lymph in urine)
hydrocele (fluid accumulation around testicles)
elephantiasis

Question 20

Elephantiasis in men vs women

Answer 20

In men the organs most commonly affected are: scrotum, legs, and arms

in women: legs and arms are usually affected, with vagina and breasts sometimes affected

Question 21

______ attacks of ________ causes the condition called elephantiasis

Answer 21

Repeated

acute lymphatic inflammation

Question 22

What occurs in elephantiasis:

Answer 22

Skin becomes thick and cracked which allows secondary infections via fungi and bacteria

Question 23

Dx of W. bancrofti

Answer 23

Demonstration of microfilarae in the blood
Blood smears must be taken at the right time

US detect adult worm movement

X-ray detects dead and calcified worms

Question 24

Treatment of W. bancrofti

Answer 24

Hetrazan kills microfilariae and adults
Metronidazole
Surgery
Pressure bandages on swollen areas

Question 25

Prevention

Answer 25

Avoid mosquito bites in endemic areas

Insect repellents and mosquito nets

Question 26

______ also causes lymphatic filariasis

Answer 26

Brugia malayi

Question 27

Brugia malayi causes

Answer 27

Brugian filariasis

Question 28

2 key differences between Brugia malayi and W. bancrofti

Answer 28

B. mayali has 2 nuclei in tail

B. mayali is not as widely distributed

Question 29

Loa Loa causes _____ and is referrred to as the _____

Answer 29

Loa filariasis

Eye worm

Question 30

Vector for Loa

Answer 30

Chrysops

Day feeding

Question 31

Once fly bites host:

Answer 31

The L3 larva enter the bite and develop slowly, adjacent to the skin

Adult makes excursions to sub-dermal tissue where it becomes visible

They mate and produce microfilariae, which travel to the peripheral circulatory system

Question 32

Periodicity in Loa loa

Answer 32

In synchrony with fly vector, present during the day

Question 33

After loa vector takes a blood meal:

Answer 33

they develop to L3 stage in the gut and travel to proboscis where they are infective to the definitive host

Question 34

Infective stage to human in Loa loa

Answer 34

L3

Question 35

Pathogenesis in Loa loa:

Answer 35

When adults travel they cause pain, they can often be seen in the eye where they can be removed before causing further damage

Question 36

Immune reaction in Loa loa host

Answer 36

Calabar swellings in arms and legs

Also caused by the worm being stationary

Question 37

Dx of Loa loa

Answer 37

demonstration of microfilariae in the blood

Question 38

Treatment

Answer 38

Surgical removal
Hetrazan kills microfilariae and adults
Metronidazole

Question 39

Prevention/control of Loa loa

Answer 39

Control of deer flies is difficult; they breed in swampy forests

Avoid the bites of deerflies

Wear long pants and sleep in well-screened areas