Curb the dengue and malaria menace with early diagnosis

With the spike in malaria and dengue during the monsoons, clinicians are faced with the challenge of quick and accurate testing and finding new ways to reach out to the endemic areas. Since both these vector-borne diseases exhibit symptoms also evident in many other viral infections, the onus is on the laboratories to select testing methods that correctly identify the parameters specific to these two diseases.

A swell in the volume of cases each year, has brought Rapid Diagnostic Tests (RDTs) into the limelight. RDTs offer pathologists an immediate answer to whether a person is infected or not and are an ideal choice in a resource constraint setting. Besides offering a faster response time, RDTs also offer the benefit of combination tests (NS1 Ag and differential IgG / IgM Ab in the case of dengue and differential diagnosis of falciparum and vivax infection, in the case of malaria) which is particularly advantageous when patients report on the fourth or fifth day of fever, with some other ambiguous symptoms and in cases of secondary infection.

While the market is flooded with numerous RDTs, it is important to choose a kit with proven sensitivity and specificity. The use of gold nano-particles for easy interpretation and monoclonal antibodies to minimize false results, has helped increase the reliability of the RDTs. However, though devised to make diagnosis convenient and quick, RDTs should be complimented with comprehensive ELISA tests.

In the case of malaria, reportable antigens such as plasmodium LDH (common for all four species of the plasmodium parasite) or HRP-2 Antigen (unique to P. falciparum) give a clear-cut indication of infection and are preferred over antibody tests. Antibody tests, have often been found to trigger false negative results in case of initial stages of infection, owing to the time required for development of the antibody; and false positive results due to persistence of antibodies after clearance of an infection.

Speaking of the conventional methods, ELISAs still remain the method of choice for their accuracy, particularly in the initial days of the infection and in cases of heavy workload and a lab setup complete with an ELISA reader and washer. The good news, several independent studies have indicated the correlation between the results obtained by RDTs and ELISAs!

Further, hematology parameters such as increased hematocrit or decreased platelet counts are critical to early diagnosis of severe dengue cases. Immature Platelet Fraction (IPF) is a useful index for predicting platelet recovery and avoiding unnecessary transfusions in dengue for patients having low platelet count. HFLC* (High Fluorescence Lymphocyte Count) also helps in differentiating and monitoring the severity of the dengue infection. Similarly, for malaria, iRBC flag serves as a useful and critical indicator for quick detection of the infection.

Polymerase Chain Reaction (PCR) is another method for detection and though more accurate than microscopy, it requires a specialized laboratory and expensive instrumentation. Therefore, molecular tests are generally preferred only in asymptomatic cases.

The Government too, on its part, is taking initiatives to aid early and accurate diagnosis of the infections. Prohibiting the manufacture, sale and distribution of antibody detecting rapid diagnostic tests for malaria is one such step. Additionally, the Union Health Ministry’s initiatives such as National Vector Borne Disease Control Programme, Essential Diagnostics List, a mobile app for creating awareness, and surveillance hospitals with laboratory support in endemic areas, all aim at providing universal access to equitable, affordable and quality healthcare services for prevention and control of malaria and dengue.

Thus, manufacturers and the health ministry are taking conscientious efforts to ensure the curb of the dengue/ malaria menace. On their part, diagnostic service providers need to ensure that they choose tests/ instruments that have been assessed and approved by reference reputed labs for their sensitivity and specificity.

Transasia Bio-Medicals Ltd. offers both ELISA and rapid kits for detection of malaria and dengue. Infact, its ErbaQik Dengue Duo, for the detection of NS1 Ag and IgG/ IgM antibody, utilizes unique Black Gold Particle in the conjugate to create distinctly coloured bands, giving it a unique dual colour advantage. It is the only bi-colour detection immuno-chromatographic device in India with enhanced sensitivity and specificity and has been validated and approved by reputed NABL accredited laboratories.

Additionally Transasia also offers ELISA test menu for dengue and malaria and hematology analyzers for enumeration of IPF, HFLC* and iRBC flagging.

*Research parameter