Dengue

Introduction Dengue fever is caused by one of four closely related antigenically distinct Flavivirus Serotypes DEN-1, DEN-2, DEN-3 & DEN-4. Virus is transmitted by day biting mosquito Aedes aegypti. Infection with one of the four strains of dengue virus usually produces immunity to that strain but does not provide protection against the other strain. Dengue fever is characterized by the rapid development of a fever that may last from 5 to 7 days with intense headache, joint & muscle pain and a rash. The hemorrhagic form of the dengue fever is more severe and associated with loss of appetite, vomiting, high fever, headache and abdominal pain. Shock and circulatory failure may occur and hemorrhagic dengue results in death up to 50% of the untreated cases. Dengue patient can die if not diagnosed and treated at the right time. There is no specific treatment of dengue fever available. No dengue vaccine yet commercially available. The epidemics in India are associated with multiple dengue serotypes, but DEN-3 is predominant.

Diagnosis

  • Serological analysis of suspected patient is well established method for the diagnosis of dengue in addition to isolation of the virus from the specimen of suspected patient.
  • Different techniques e.q. ELISA, Immunochromotographic and PCR, are being used in the diagnosis of Dengue.
  • The virus isolation from the patient sample is very costly, time consuming technique & needs technical expertise.
  • PCR technique detects genetic material of virus itself and has lot of limitations.
  • ELISA & Immunochromotographic techniques detects qualitative or quantitative levels of IgM, IgG or IgM+IgG antibodies in serum, plasma or whole blood.
  • ELISA tests can quantify the level of antibodies but techniques is time consuming, needs instrumentation and technical expertise.
  • ELISA tests can not be used as POC (Point Of Care) test.
  • Immuno chromatographic tests can be used only for the qualitative diagnosis of antibodies but have various advantages over other techniques e.q.:

Can be used as POC test.
Ready to use with whole blood analysis.
Instant result with visual interpretation
Can be used in remote areas also where a well established laboratory and expert technician is not available.

NANO DENGUE TEST: INTRODUCTION

Principle

The Dengue IgG/IgM test kit is a sandwich immunochromatographic membrane based screening test to detect the antibodies for dengue virus. The test can be used either with serum, plasma or whole blood. The test employees the use of colloidal gold particle conjugated with IgG &IgM binding proteins and a unique combination of dengue antigen immobilized on the membrane at T. After the addition of sample and running buffer in the sample well of test device, the mixture passes through the conjugate gold and makes an immune complex. The immune complex will bind with the antigen immobilized at test zone (T) of the test device if antibodies of dengue present in the sample. The remaining immune complex continues to migrate to a control area (C) in the test device and produces a colored band in the control (C) zone. The control band indicates that the test has been performed properly and is in working condition. Appearance of pink/purple band at test (T) in addition to band at control(C) indicates that sample is positive for dengue antibodies.

Features

  • It is qualitative card test for the detection of dengue antibodies (IgG & IgM) in the specimen.
  • The test is based upon immunochromatographic principle.
  • The specimen choice for the analysis is SERUM, PLASMA OR WHOLE BLOOD.
  • The specimen volume of serum / plasma is 5 µl and for whole blood 10 µl is required.
  • Ready to use running buffer provided with the test / kit.
  • Recommended storage of the test kit is 4-300C.
  • Shelf life of the test up to 24 months from date of manufacturing if stored at recommended storage conditions.
  • A specially designed test device having TWO result windows, one for IgG and another for IgM antibody result.
  • Result in form of pink / purple lines - separate lines for IgG and IgM antibodies.
  • Result within 20 minutes of sample and running buffer addition.
  • A very suitable test format for POC testing and for remote areas where other techniques are not suitable.
  • A highly specific cocktail of the recombinant antigens used in the test strip having NO CROSS REACTION with other viruses of Flavivirus family.

Test procedure

  • Take Dengue test and place on flat surface.
  • Add 5 ul of serum/plasma or 10 ul whole blood to the sample well of the test device using micro pipette.
  • Add 2-3 drops of running buffer provided in the dropper bottle.
  • Read results in 5-20 minutes of sample and buffer addition. DO NOT INTERPRET THE RESULT AFTER 20 MINUTES.

Interpretation of Results

Positive: Appearance of two colored bands, one in the test zone (T) and another in the control zone (C) indicates that sample is positive for antibodies of dengue virus.

Negative: Appearance of only one pink/purple band in the control zone (C) indicates that sample is negative for antibodies of dengue virus.

Invalid: If the colored band does not appear in the control zone (C), the test is invalid and should be repeated.

 

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