Onchocerca volvulus Flashcards
Onchocerca volvulus
• Also known as the_______
“Blinding Worm”
Onchocerca volvulus
Disease:
- Onchocerciasis
- Onchocercosis
- River blindness
Onchocerca volvulus
Microfilariae
- only pathogenic_____ nematode which is not sheathed
- continuous nuclei at the tip of the tail
- found in nodules under_____, not in______
tissue
skin; peripheral blood
Onchocerca volvulus
skin
eye
•
Clinical Significance / Disease:
- severe______
- microfilaria in ocular structures may result in_____
- leading cause of blindness in_____
dermatitis
blindness
Africa
Onchocerca volvulus
• Diagnosis:
- demonstrate from_____________ unsheathed microfilariae with no nuclei in tail
skin snips/tissue scrapings
AKA
Blinding Worm
Vector:
Female Simulium Blackflies
Infective Stage:
Third Stage Larva (L3)
Diagnostic Stage:
• Microfilaria in
• Adults in
skin, lymphatics, occ’l in blood, urine, sputum;
Lymph nodes
Habitat:
Subcutaneous tissues, lymphatic
Epidemiology
• Found in
Africa, and Central and South America
In areas with fast-flowing rivers
• River Blindness
The female
Produce microfilariae in the subcutaneous nodules for___ years
9
Biology: Microfilaria
• Location:
Occasionally (3)
nodules under the skin
• Occasionally, in the blood, urine, sputum
Sheath?
Nuclei at the tip?
• Unsheathed
• No - nuclei at the tip of the tail
Adults in the
Subcutaneous nodule
causes symptoms of Onchocerciasis
Wolbachia
shows potential as an anti-Wolbachia treatment, leading to the death of adult parasitic worms.
Doxycycline
Pathogenesis and Clinical Manifestations
Onchocerciasis
: most serious manifestation
• River blindness
Pathogenesis and Clinical Manifestations
Onchocerciasis
• subcutaneous nodules
Onchocercoma
Pathogenesis and Clinical Manifestations
•_______ atrophy and dryness of the skin, itchy
• Pruritus, dermatitis
•_______
Lizard Skin
Hanging Groin
Pathogenesis and Clinical Manifestations
River blindness
Onchocercoma
Lizard skin
Hanging groin
Diagnosis
Skin snips
Biopsy of skin nodules
• Microfilaria (Anytime)
• Wet Mount
• Stained with Giemsa or Hematoxylin
Skin Snips
Diagnosis
• Adult worm with Wolbachia and microfilariae
Biopsy of Skin Nodules
Treatment
•: kills larvae
•: kills Wolbachia, thus, killing adults
Ivermectin
Doxycycline
hypersensitivity reaction due to lysis of worms
Mazzotti Reaction
• Itchiness of the skin with rashes, swelling, hives,
• More severe to those who have never taken ivermectin yet
Mazzotti Reaction
Old drugs but no more recommended:
: Kills microfilariae —> accelerates river blindness
: Kills adult worm, highly toxic
• Diethylcarbamazine (DEC)
Suramin
Prevention and Control
• Insect repellant
• Wearing clothes covering skin
