Onchocerca volvulus

Question 1

Onchocerca volvulus

• Also known as the_______

Answer 1

“Blinding Worm”

Question 2

Onchocerca volvulus

Disease:

Answer 2

• Onchocerciasis
• Onchocercosis
• River blindness

Question 3

Onchocerca volvulus

Microfilariae

• only pathogenic_____ nematode which is not sheathed
• continuous nuclei at the tip of the tail
• found in nodules under_____, not in______

Answer 3

tissue

skin; peripheral blood

Question 4

Onchocerca volvulus

skin

eye

•

Clinical Significance / Disease:

• severe______
• microfilaria in ocular structures may result in_____
• leading cause of blindness in_____

Answer 4

dermatitis

blindness

Africa

Question 5

Onchocerca volvulus

• Diagnosis:

• demonstrate from_____________ unsheathed microfilariae with no nuclei in tail

Answer 5

skin snips/tissue scrapings

Question 6

AKA

Answer 6

Blinding Worm

Question 7

Vector:

Answer 7

Female Simulium Blackflies

Question 8

Infective Stage:

Answer 8

Third Stage Larva (L3)

Question 9

Diagnostic Stage:

• Microfilaria in

• Adults in

Answer 9

skin, lymphatics, occ’l in blood, urine, sputum;

Lymph nodes

Question 10

Habitat:

Answer 10

Subcutaneous tissues, lymphatic

Question 11

Epidemiology

• Found in

Answer 11

Africa, and Central and South America

Question 12

In areas with fast-flowing rivers

Answer 12

• River Blindness

Question 13

The female

Produce microfilariae in the subcutaneous nodules for___ years

Answer 13

9

Question 14

Biology: Microfilaria

• Location:

Occasionally (3)

Answer 14

nodules under the skin

• Occasionally, in the blood, urine, sputum

Question 15

Sheath?
Nuclei at the tip?

Answer 15

• Unsheathed

• No - nuclei at the tip of the tail

Question 16

Adults in the

Answer 16

Subcutaneous nodule

Question 17

causes symptoms of Onchocerciasis

Answer 17

Wolbachia

Question 18

shows potential as an anti-Wolbachia treatment, leading to the death of adult parasitic worms.

Answer 18

Doxycycline

Question 19

Pathogenesis and Clinical Manifestations

Onchocerciasis

: most serious manifestation

Answer 19

• River blindness

Question 20

Pathogenesis and Clinical Manifestations

Onchocerciasis

• subcutaneous nodules

Answer 20

Onchocercoma

Question 21

Pathogenesis and Clinical Manifestations

•_______ atrophy and dryness of the skin, itchy
• Pruritus, dermatitis

•_______

Answer 21

Lizard Skin

Hanging Groin

Question 22

Pathogenesis and Clinical Manifestations

Answer 22

River blindness
Onchocercoma
Lizard skin
Hanging groin

Question 23

Diagnosis

Answer 23

Skin snips
Biopsy of skin nodules

Question 24

• Microfilaria (Anytime)

• Wet Mount

• Stained with Giemsa or Hematoxylin

Answer 24

Skin Snips

Question 25

Diagnosis

• Adult worm with Wolbachia and microfilariae

Answer 25

Biopsy of Skin Nodules

Question 26

Treatment

•: kills larvae

•: kills Wolbachia, thus, killing adults

Answer 26

Ivermectin

Doxycycline

Question 27

hypersensitivity reaction due to lysis of worms

Answer 27

Mazzotti Reaction

Question 28

• Itchiness of the skin with rashes, swelling, hives,

• More severe to those who have never taken ivermectin yet

Answer 28

Mazzotti Reaction

Question 29

Old drugs but no more recommended:

: Kills microfilariae —> accelerates river blindness

: Kills adult worm, highly toxic

Answer 29

• Diethylcarbamazine (DEC)

Suramin

Question 30

Prevention and Control

Answer 30

• Insect repellant

• Wearing clothes covering skin