Haematology

I have been attached to Haematology lab for three weeks. Normally, i performs routine tests like FBC, PBF, ESR and other miscellanous tests like dengue serology test and malaria parasite screening. erm.. so here i will elaborate on the dengue serology test.

Dengue Serology Test

Purpose
It is performed to obtain a qualitative presumptive detection of IgG and IgM antibodies, as well as a presumptive differentiation between primary and secondary infection.

Principle
Serum antibodies of the IgM/IgG class, when present, bind to the anti-human IgM/IgG immobilized in 2 lines across the test strip. The colloidal gold-labeled antiflavivirus monoclonal forms complexes with the dengue antigen that is captured by dengue specific IgM/IgG in the patient’s serum. These complexes are visualized as pink/purple line(s).

Sample requirement
- At least 1ml of capillary/venous blood collected in plain tube
- Centrifuge the sample at 3000 rpm for 10 minutes
- Sample serum should be preferably clear, non-haemolysed, non-lipaemic and non-icteric.

Method:
Use the Denge Duo IgM and IgG Rapid Strip Test Kit (PanBio)
Pipette 10μl of the serum onto the strip kit and the result is to be viewed after 15 minutes. Before conducting this test, the kit is kept in the fridge and so when this test is requested, we have to take it out and keep it in the room temperature for 10-15 minutes.

Dengue results are reported in LIS as follows:

Results Interpretation

Control positive only
If dengue infection is strongly suspected, consider PCR for dengue virus. Within 1st 5 days of illness. If this is an acute specimen, PCR can be performed on the sample, which has been retained in the lab.

IgM and Control positive
Consistent with 1° dengue. Occasional false positive may occur in certain infections such as measles.

IgM, IgG and Control positivie
Consistent with 2° dengue

IgG and Control positive
Consistent with 2° dengue. Cross reactivity may occur with flavivirus.

Primary (1°) infection is characterized by the presence of detectable IgM antibodies 3-5 days after the onset of infection.
Secondary (2°) infection characterized by the elevation of specific IgG antibodies 1-2 days after the onset of infection and in the majority of the cases this generally accompanied by an elevation of IgM.

that's all for this entry. enjoy reading. take care all man. enjoy ur SIP. =)

Doreen (tg o1)