Dengue and a chikungunia tests

 Mainly Dengue testing is split up into 2 classes

1. Direct Tests

2. Indirect Tests

Direct test 

1.1. Dengue NS1 Antigen

This test is performed early in the course of infection, usually within the first 5 days of the onset of symptoms. This is because NS 1 antigen starts to appear from the very first day of dengue infection and may be present for up to 5-7 days. Thereafter, it starts disappearing from the body and may therefore indicate false-negative results.

1.2 Dengue RT-PCR test

This test is also used to detect the dengue virus in the early method from  5 to 7 days of the disease. It detects the viral genome ie genetic material of the virus in the blood. This test is around 90% sensitive and 95% specific against the infection. This is the most sensitive and specific test recommended to be taken in the preliminary phase of the infection. The Dengu PCR test should be done within 5 days after the symptoms start to seem.

Indirect Tests

2.1  Immunoglobulin M (IgM) test for Dengue

This test detects IgM (antibodies) in the blood, which occur in the first phase of the disease, and signifies acute infection or current infection. It is informed to undergo a Dengue antibody IgM test if you experience the symptoms of dengue continue for more than 5 days. It is usually done after the 4th day of the occurrence of the symptoms as the antibodies start developing after 4-5 days of infection

2.2 Immunoglobulin G (IgG) test for Dengue

The test is manipulated to detect infection in the later course of the disease because the level of IgG which is to be controlled in the test tends to increase gradually. Usually, IgG antibodies are detectable in low quantities starting around 14-21 days of the infection, after which they slowly boost. These antibodies can continue in the blood for around 90 days and in some cases may remain for the rest of your life. We can get an IgG antibody test for Dengue after 14-21 days of infection or even later as these antibodies remain in the blood several months post infection. The presence of IgG antibodies signify previous infection, and recovery after dengue or post vaccination against dengue.

2.3 Complete Blood Count

Dengue is frequently associated with decreased platelet count (normal platelet count lies in the range of 1.5 to 4 lacs). Therefore, the platelet count should be monitored carefully and regularly, especially when the fever comes down. 

If a patient is positive for dengue-specific antigen, a decrease in platelet count and a decrease in total white blood cells (WBC) count may be seen. But, it is important to know that the diagnosis of dengue does not depend exclusively on platelet counts.

Period Dengue RT-PCR continues the extensively sensitive and specific test for dengue, a combined NS1 antigen & IgM are also valuable in detecting early disorder.

Different methods can be manipulated for the diagnosis of chikungunya virus infection. Serological tests, particularly enzyme-linked immunosorbent assays (ELISA), may demonstrate the presence of IgM and IgG anti-chikungunya antibodies. IgM antibody levels are highest 3 to 5 weeks after the onset of illness and persist for about 2 months. 

The virus may be directly detected in the blood during the first rare days of infection as well. As such, samples collected during the first week of illness should be tested by both serological and virological methods (particularly reverse transcriptase–polymerase chain reaction (RT–PCR)). Various RT–PCR methods are available but with variable sensitivity. Some are satisfied with clinical diagnostics. RT–PCR products from clinical samples may also be used for genotyping of the virus, permitting comparisons with virus samples from different geographical origins

Viral culture is the most important method to recognize viruses in the early 3 days of illness.  Chikungunya virus should be manipulated under biosafety level (BSL) 3 conditions for the 1st 8 days.  Viral RNA of Chikungunya can be distinguished from serum.

Commonly antibodies of the Chikungunya virus develop toward the end of the first week of illness. Therefore, to definitively rule out the diagnosis, convalescent-phase samples should be received from victims whose acute-phase samples test negative

Nucleic Acid Amplification Test (NAAT)

           A NAAT is a molecular test used to detect viral genomic material

           NAAT assays are the preferred method of diagnosis because they confirmed evidence of infection.

NS1 Detection

         

• NS1 tests can be as susceptible as a molecular test during the first 0-7 days of symptoms.
• NS1 tests identify the non-structural protein NS1 of the dengue virus. This protein is discharged into the blood during the dengue virus.

• NS1 tests have been cultivated for use in serum. Most of these tests use synthetically titled antibodies to perceive dengue NS1 protein
• A positive NS1 test result is signifying of a dengue infection but does not deliver serotype information. Knowing the serotype of the infecting virus is not necessary for patient care; however, if serotype advice is needed for supervision purposes, the sample should be assessed by NAT.
• However analyses show that NS1 can be found in whole blood or plasma, most NS1 tests have been developed and analyzed in serum samples. While integrated testing with an NS1 and IgM antibody test can usually deliver a diagnostic result during the first 1-7 days of illness, a second, convalescent condition specimen should be collected and tested for IgM when both antigen and antibody tests are unfavourable
• 
  
• .