Onchocerca volvulus Flashcards
(18 cards)
What is the common name for Onchocerca volvulus?
Convoluted filaria
What is the primary habitat of adult Onchocerca volvulus worms in humans?
Nodules in the subcutaneous tissue of man
What is the mode of transmission for Onchocerca volvulus?
Skin penetration (via blackfly bite)
What is the infective stage of Onchocerca volvulus?
L3 larvae
What is the diagnostic stage of Onchocerca volvulus?
Microfilariae
What is the definitive host for Onchocerca volvulus?
Man
What is the intermediate host (biological vector) for Onchocerca volvulus?
Day-biting female blackfly of genus Simulium
Describe the general characteristics of adult Onchocerca volvulus worms.
White, opalescent & transparent with transverse striations on the cuticula.
Describe the key morphological features of Onchocerca volvulus microfilariae, especially their sheath and tail nuclei.
Unsheathed; NO nuclei in tip of tail.
What type of periodicity do Onchocerca volvulus microfilariae exhibit in the blood?
Non-periodic (typically reside in skin, not peripheral blood)
Where are Onchocerca volvulus microfilariae typically found, and when might they be seen in blood or urine?
Typically reside in skin, but may be found in blood or urine during heavy infections.
What severe eye condition can Onchocerca volvulus cause?
River blindness
A nodule containing encapsulated adult worms.
“Onchocercoma”
What skin condition is characteristic of Onchocerca volvulus infection, often with high eosinophilia?
Severe dermatitis (50-70% eosinophilia)
What are the common laboratory diagnostic methods for Onchocerca volvulus?
Demonstration of adult worms; Demonstration of microfilariae (often from skin snips, not blood); Serological test; PCR.
What are some key prophylactic measures against Onchocerca volvulus infection?
Application of insecticides to the streams where the vector is breeding.
In which geographical regions is Onchocerca volvulus commonly found?
Tropical Africa & Central America.
What are the main treatments for Onchocerca volvulus infection?
Surgical removal of detectable nodules; Diethylcarbamazine treatment.
