TESTING TESTING &TESTING

Pandemic challenge is on and one of the primary method to fight this is to test.Experts agree that mass testing for COVID-19, the disease caused by the coronavirus, would allow positive cases to be isolated and help identify those who came in contact with them, helping to curb further transmission.

But how does testing happen and how does it help? 

NAAT tests

The most commonly used coronavirus tests are the WHO-recommended Nucleic Acid Amplification Tests (NAAT), which detect the SARS-CoV-2 virus responsible for the COVID-19 disease.  

The specimen is usually collected from the upper respiratory tract using the nasopharyngeal swab technique - in which a sample is gathered from the throat behind the nose, containing a mixture of mucous and saliva.Samples are brought to a specialised laboratory and tested for SARS-CoV-2 using a real-time reverse-transcription polymerase chain reaction (rRT-PCR) assay - a method used to detect the presence of "specific genetic material from a pathogen.

Serological tests

A serological test is used to detect antibodies present in blood serum. Recently India imported rapid antibody test kits from China which turns faulty .What's so rapid about these kits? Actually these are handy ,easy to carry and thought to give fast results .The test can be performed by any one, it  need not complex setup and sophiscated laboratories.How effective these test are??,Antibodies are proteins produced by white blood cells particularly B lymphocytes to fight foreign bodies such as antigens.When an antigen binds to the B-cell surface, it stimulates the B cell to divide and mature into a group of identical cells called a clone. The mature B cells, called plasma cells, secrete millions of antibodies into the bloodstream and lymphatic system.Plasma the fluid part  which constitutes 55% of blood contains these antibodies.

                    The matter of importance is that antibody test do not hold good in initial time of incubation period that is just after the infection.Antibody of type IgG is produced .But  as infection matures IgM begins to appear.IgM is the first class of immunoglobulin made by B cells as they mature, and it is the most commonly present as the antigen receptor on the B-cell surface. 

When IgM is secreted from the cells, five of the basic Y-shaped units become joined together to make a large pentamer molecule with 10 antigen-binding sites. This large antibody molecule is particularly effective at attaching to antigenic determinants present on the outer coats of pathogens. Generation of antibody in different people may also vary based on the environment in which they are exposed .

This test is not found to be so effective but the plasma method which is being used to cure serious cases based on the antibody method.Plasma therapy is under trial ,ICMR has not yet approved it,It can be lethal if the therapy is not administered properly as it can trigger allergic reactions and self cell destruction.

There is general procedure for testing virus ,first one is blood extracted from veins secondly the chemiluminescence test and third is ELISA type of test 2nd to 3rd generation .But these test are cumbersome procedures and not so feasible as far as corona virus is concerned.The best way of testing is swab testing .

Individual testing is most common and effective but pool testing is only used in the area where there is less than 5% prevalence and not more than 5 sample is to be pooled .

Mutation and story of strain

Rna virus mutates faster but fortunately that is not the case here .Indore and Gujrat recently claimed that higher mortality rate is due to L strain but this claim is not entertained by WHO.Presently nothing can be said about their mortality rate.

Virus is somewhat becoming more homogenous which will be helping the scientist to devise vaccine more faster.This epidemic has gone more dangerous than the expectation.

Lockdown has been used to gain more time for strengthening the medical facilities but more should be done in this regard.It can be a preventive measure but not the permanent solution .