Filariasis is a parasitic disease caused by roundworm infection transmitted through mosquitoes and black flies. There are three main types that can cause long lasting and debilitating symptoms by blocking lymphatic vessels. Microfilariae larvae are spread to humans through bites from infected mosquitoes and black flies. Blood smears examined microscopically at night can detect microfilariae and diagnose active infection, while antigen and antibody tests provide alternative diagnostic methods.

2. WHAT IS Filariasis
• Filariasis (or philariasis) is a parasitic disease
caused by an infection with roundworms of the
Filarioidea type.
• These are spread by blood-feeding black flies and
mosquitoes.
• This disease belongs to the group of diseases
called helminthiasis.

4. Key features
• White, slender roundworms
• Three types:
1. Wuchereria bancrofti,
2. Brugia malayi,
3. Brugia timori
• Live for 5-7 years,
• Blockage leads to edema (collection of fluid in
tissues)

5. • Mosquitos are Vectors and spread the
Infection
• The most common vectors/carriers are:
in Africa: Anopheles species
in the Americas: Culex species
in Asia: Aedes species

6. Wuchereria bancrofti
the primary causative agent for Filariasis

7. Characters of the Adult Parasites
80–100 mm long
0.24–0.30 mm in diameter
about 40 mm long
0.1 mm in diamete

8. How the Larva Appear
• A microfilaria is about 240–300 µm
(micrometers) long and 7.5–10 µm thick.
• It is sheathed and has nocturnal periodicity.
• It has a gently curved body, and a tail that is
tapered to a point.
• The nuclear column (the cells that constitute
its body) is loosely packed. The cells can be
seen individually under a microscope and do
not extend to the tip of the tail.

14. • The standard method for diagnosing active
infection is the identification of microfilariae in a
blood smear by microscopic examination.
• The microfilariae that cause lymphatic filariasis
circulate in the blood at night (called nocturnal
periodicity).
• Blood collection should be done at night to
coincide with the appearance of the microfilariae,
and a thick smear should be made and stained.

15. Smear showing microfilaria Fna of lymph node showing microfilaria

16. • Serologic techniques provide an alternative to
microscopic detection of microfilariae for the
diagnosis of lymphatic filariasis. Patients with
active filarial infection typically have elevated
levels of ant filarial IgG4 in the blood and
these can be detected using routine assays.
• Antigen detection: Circulating filarial antigen
(CFA) - 'gold standard' for diagnosing
Wuchereria bancrofti infections.

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