Microfilaria (Blood)

Testing Laboratory

Auckland Te Toka Tumai | Auckland Hospital

Department

Haematology

Delphic Registration Code (Alpha Code)

FIL

Test Code (Numeric Code)

1020

Laboratory Handling

Phlebotomy

Collect 1x 3ml EDTA (Lavendar cap) blood sample.

Transport

Store and transport samples at ambient room temperature or refrigerated (2°C–8°C).

Registration

Please register test code FIL.

Separating

EDTA - Do not spin.

Laboratory

LabPlus Special Haematology

Test Adds Requirement

Do not load on the 8100.

If a printout of FBC results is received send with sample. If testing is delayed past 48 to 72 hours, sheathed microfilariae may lose their sheaths (ex-sheath), which can lead to misidentification of the species.

Sample Stability

An EDTA blood sample for microfilaria testing remains stable for up to 72 hours (3 days) before cellular disintegration compromises the parasite.

Synonyms

Filaria

Turnaround Time

1 day

Analysed daily Monday to Friday.

Specimen Type

• Whole Blood

Specimen Requirements

Tube/Container Type:

Preferred

• EDTA (Lavender Cap)

Preferred Sample Volume (ml)

3

Minimum Sample Volume (ml)

3

No of Samples Required

1

Paediatric Specimen Requirements

Tube/Container Type:

Preferred

• EDTA (Lavender Cap)

Preferred Sample Volume (ml)

3

Minimum Sample Volume (ml)

1

Test Method

Manual process-Wet film, buffy coat film and and concentration using filter. Blood Film examination

Limitations / Interference

Microfilaria screening in humans is limited by strict timing requirements for blood collection, low sensitivity during light infections, and the need for invasive skin or blood sampling

Microfilariae remain viable and detectable in EDTA anticoagulated blood for up to 3 days.
If testing is delayed past 48 to 72 hours, sheathed microfilariae may lose their sheaths (ex-sheath), which can lead to misidentification of the species.

Preparing thick and thin smears immediately after collection is ideal if transport to the laboratory will take longer than a few hours.

Microfilariae exhibit a marked periodicity depending on the species involved, therefore the time of specimen collection is critical. If a filarial infection is suspected, the optimal collection time for demonstrating microfilariae is:

Loa loa—midday (10 AM to 2 PM)
Brugia or Wuchereria—at night, after 8 PM
Mansonella—any time
Onchocerca—any time

Wuchereria bancrofti var. pacifica does not show nocturnal periodicity; instead, it exhibits a diurnal sub periodic pattern where microfilariae are present in the peripheral blood throughout the day with a peak concentration in the afternoon.

Contact Information