Microbiology
| Full details for "Filaria serology". | |
|---|---|
Name |
Filaria serology |
Alternative name/Profile |
lymphatic filariasis / elephantiasis / Wuchereria bancrofti / Brugia malayi / Brugia timori/Onchocerca volvulus and Loa loa |
Department |
Microbiology |
Investigation |
A filaria ELISA, using Brugia pahangi as antigen is used as a “generic” screening test.The filaria ELISA is a non-specific screening test that is positive in many types of filariasis and in strongyloidiasis. It is most useful in the diagnosis of TPE (Tropical Pulmonary Eosinophilia) where high antifilarial antibody levels are required to make the diagnosis. |
Specimen type |
6ml clotted blood |
Sample type |
Serum |
Sample container & volume |
6 ml Red top clotted blood |
Frequency of analysis |
By arrangement |
Turnaround time |
28 Days |
Availability |
|
Notes |
A filaria ELISA, using Brugia pahangi as antigen is used as a “generic” screening test. A minimum of 0.5ml of serum is required. A negative result does not exclude the diagnosis and this is especially so with onchocerciasis. Blood examination for detection of microfilariae should be performed for all individuals for whom the diagnosis of filariasis is suspected. The syndromes produced by the various species of filarial worms are usually associated with eosinophilia. A patient with an eosinophilia who has lived in, or visited, a filaria endemic area might reasonably be tested for filariasis. The major human filariases are Wuchereria bancrofti, Onchocerca volvulus, Brugia malayi, and Loa loa. With the exception of Onchocerca volvulus, a definitive diagnosis of filariasis is usually made by the demonstration of microfilariae in the peripheral blood. Onchocerca volvulus is diagnosed by demonstration of microfilariae in skin snips. Twenty millilitres of anti-coagulated blood (citrate tube) are required so that the microfilariae can be detected by filtration. Day blood (for Loa loa) should be taken between 12noon and 2pm local time and night blood (for Wuchereria bancrofti) at 12 midnight. Samples should be kept at room temperature until processed. Specimens sent to Department of Clinical Parasitology, Hospital for Tropical Diseases, 3rd Floor, Mortimer Market Centre, Capper Street, London, WC1E 6JB Tel: 0044 203447518 Send sample to the laboratory without delay. The clotted blood sample for Filaria serology can be stored and transported at room temperature. |
Related links |
HSL User Guide 2022 |
Reference range |
Positive results are reported at Levels 1 to 9. Levels 1 and 2 are regarded as weak positives; Levels 5 and over are strong positives. Reactive symptomatic cases with moderate eosinophilia tend to give high level positives. Non-reactive cases, which may be asymptomatic though microfilariae are present, give low levels of positivity and may be negative. Known causes of false positive results are Hookworm (about 50% of cases) and occasionally Ascaris infection. Filaria infections are not speciated using ELISA test. This may be done if microfilaria are seen in a blood film or by staining the microfilaria obtained by filtration. |
Last updated |
Tue, 14 Jan 2025 10:09:49 GMT |