Dracuculiasis/Onchocerciasis

Question 1

Dracuculiasis also called…

Answer 1

Guinea Worm Disease

Question 2

Pathogenic agent name:

Dracuculiasis

Answer 2

D. medinensis

• Female carries embryos and creates blister under the skin
• Males die and get encapsulated in tissue

Question 3

Vector:

Dracuculiasis

Answer 3

Copepod

Question 4

Distribution:

Dracuculiasis

Answer 4

Afrrica (Chad, Ethiopia, Mali, South Sudan)

Asia

Question 5

How is Dracuculiasis transmitted to humans?

Answer 5

• Drinking stagnant water contaminated with tiny infected water fleas

Question 6

Reservoirs:

Dracuculiasis

Answer 6

Humans only reservoir

Question 7

Transmission Mechanism:

Dracuculiasis

Answer 7

• Humans drink contaminated water
• Larvae released in host stomach and intestinal wall
• Female worms migrate to surface of skin and release larvae which causes itching
• Person sticks limb in water for release and larvae are released

Question 8

Clinical Findings:

Dracuculiasis

Answer 8

• 1 year after infection - painful edema, blister with worms emergins, ulcer
• Asymptomatic for year then slight fever

Question 9

Diagnosis:

Dracuculiasis

Answer 9

• X-ray (encapsulated worms)

Question 10

Treatment (drugs):

Dracuculiasis

Answer 10

None

Question 11

Prevention:

Dracuculiasis

Answer 11

• None
• Health education/behavioral changes
• Eradication via safe water and larvicides
• Case containment

Question 12

What is the largest parasite infecting humans?

Answer 12

Dracuculiasis (1 meter long)

Question 13

What is the death rate for Dracuculiasis?

Answer 13

Rare

Question 14

Other name for Onchocerciasis?

Answer 14

River Blindness

Question 15

Pathogenic Agent:

Onchocerciasis

Answer 15

O. volvulus

20 inches, female worms produce millions of microfilariae
(Migrate under the skin)

Question 16

Vector:

Onchocerciasis

Answer 16

Simulium black glies

Question 17

Distribution:

Onchocerciasis

Answer 17

• Sub-saharan Africa (Africa’s Rain forest belt)

- Tropical regions

Question 18

Africa’s Rain Forest belt is inflicted with…

Answer 18

Onchocerciasis

Question 19

Reservoirs:

Onchocerciasis

Answer 19

Humans only known host

Question 20

Forms of onchocerciasis (2) and their associations

Answer 20

• Savannah form (associated with blindness)

- Forest form (associated with skin disease)

Question 21

How is Onchocerciasis transmitted to humans?

Answer 21

The bite of the simulium black fly when it bites to feed (deposits larvae)

Question 22

Transmission Mechanism:

Onchocerciasis

Answer 22

• Simulium black fly bites and deposits larvae

Question 23

Clinical Findings:

Onchocerciasis

Answer 23

• Freely movable nodules, lymphadenopathy
• “Hanging groins”
• Punctate keratis (death of cells in the eye)

Question 24

“Hanging groins” is associated with …

Answer 24

Onchocerciasis

Question 25

Diagnosis:

Onchocerciasis

Answer 25

• Skin snips - gold standard (2 snips incubated in saline for 24 horus to see microfilariae)
• Worms in nodules
• PCR of the skin if no visible worms
• Antigen test - positive only with active infection

Question 26

Treatment (Drugs):

Onchocerciasis

Answer 26

• Ivermectin (drug of choice)

- Doxycycline - kills Wolbachia and reduces production of microfilariae by adult worms

Question 27

Ivermectin works how in onchocerciasis

Answer 27

Kills microfilariae not adults in a single dose

Question 28

Doxycycline works how in onchocerciasis

Answer 28

Kills Wolbachia and reduces production of microfilariae by adult worms

Question 29

Prevention:

Onchocerciasis

Answer 29

• No vaccine
• Control vector (fly)
• Use of insecticide to kill larvae

Question 30

Onchocerciasis likes to be near what body part?

Answer 30

Prominences (hops)

Question 31

Onchocerciasis worms are similar to…

Answer 31

• Lymphatic filariasis

- Dracuculiasis

Question 32

Onchocerciasis can effect what organ later in life?

Answer 32

• Eye

- Via optic nerve leading to blindness in 4th decade of life