Filarial nematodes Flashcards
What is this?
Wuchereria bancrofti microfilaria
Causes 90% of LF. Vector = all 3 main mosquito types
- sheathed (paler stain)
- nuclei stain purple and are sharply defined
- nuclei do not extend all the way to the tip of the tail.
What is this?
Brugia malayi microfilaria
Causes Lymphatic Filiariasis, vector = Aedes or Mansonia
- sheathed
- usually ‘kinked’
- tail is tapered, with a gap between last nuclei
What are these?
Left: W. Bancrofti microfilaria.
Sheath does not stain, while the nuclei stain deep blue
Right: B Malayi microfilaria.
Sheath is pink-staining, while the nuclei stain deep purple
What is this?
Loa Loa microfilaria
Causes Loaisis (African eye worm disease). Vector = Chrysops fly
- sheathed
- nuclei extends to the tip of the tail, which is often bent to one side
What is this?
Mansonella perstans microfilaria
- unsheathed
- smaller than other microfilariae
- nuclei extend to the tip of the tail
- tail is blunt
Spread by culicoides midges
West, East, and Central Africa
Mostly asymptomatic, can cause Loa Loa type or non -specific symptoms
What are these?
Left: Loa Loa microfilaria
Right: M. perstans microfilaria
What are the 3 methods of laboratory diagnosis of filariasis?
- membrane filtration + microscopy
- Knott’s concentration + microscopy
- antigen detection (ICT/Binax card using finger prick blood)
What are the pros + cons of the antigen detection test?
Pros:
-sensitivity 96%
-blood can be taken any time of day
-quick + easy
-no cross reactions
Cons:
-only detects Wuchereria bancrofti antigens
-can still be positive 18 months after treatment
