It is based on an immunoassay technique called IgM-capture ELISA (Enzyme-Linked Immunosorbent Assay) which involves the detection of anti-dengue IgM antibodies circulating in the blood of dengue patients. The test is useful for the laboratory confirmation of dengue infection diagnosed on the basis of clinical symptoms.

The St. Luke’s Dengue Serological Detection Test is the first locally developed serological diagnostic test for dengue in the Philippines. It is rapid, sensitive and specific, requiring only a single blood sample to confirm dengue infection. Blood samples collected on the third to seventh day of fever will give the best results.

The two key re-agents needed for this test are not commercially available. These re-agents have been developed and are presently produced by RBD using its collection of serum samples from dengue patients coming from all over the Philippines. Over 8,000 serum samples, collected from 1995 to the present, are housed in the Dengue Serum Bank at RBD.

This serum bank is a valuable source of raw materials for the reagents needed for this test. One reagent is the dengue antigen produced from selected dengue virus strains in RBD’s collection. The second reagent is the labeled anti-dengue antibody obtained from the dengue-positive sera.

In dengue infection, the presence of dengue virus in the blood stimulates the production of antibodies against it. The first kind of antibody formed is immunoglobulin M or IgM. The test developed in RBD detects the specific IgM antibodies against dengue virus by a series of binding reactions.

The final product of the reactions is visualized by the development of a yellowish-brown color. The intensity of the color, which indicates the level of anti-dengue IgM in the blood, is measured by an instrument called an ELISA Plate Reader.

The St. Luke’s Dengue Serological Detection Test was launched in July 2001. Since then, this IgM-capture ELISA test has been used to detect dengue infection in almost 8,000 cases. It has been tested and validated against other commercial dengue test systems in the market. It is currently being used in a nationwide dengue surveillance program conducted by the Department of Health.

The test is performed by the Molecular Immunology Laboratory of RBD every day, Monday to Friday. Samples for testing may be sent to RBD anytime. Results will be available three working days after receipt of sample.