Sensitive, Speedy
What is NAT?
NAT, or nucleic acid testing, is used for detecting HIV, hepatitis-B and hepatitis-C. It can detect very low levels of the virus by rapidly making copies of the genetic material.
What are the benefits?
The test reduces the detection window period, thus limiting the spread of viral diseases. Not only does it allow early HIV detection, enabling early treatment, it also prevents transfusion of infected blood.
Detection time (days)
| Disease | Normal Through | NAT |
| Hepatitis-B | 50 | 5 |
| Hepatitis-C | 40 | 10 |
| HIV | 10 | 4 |
What is the cost of the test?
Rs 800
Where is it available?
It is now available in a few private hospitals. Government hospitals will conduct the test for free for donors to keep out infected blood.
Why NACO likes it...
NACO is a strong supporter of the NAT test, as it could prove a major weapon in the fight to check the spread of AIDS through early detection. NACO is also working on reviving its plasma fractionation centre, which will produce quality plasma for patients needing transfusion, and the NAT test will ensure high quality and virus-free blood for the purpose.
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A new technique of blood testing that substantially reduces the time taken to detect the hepatitis-B, hepatitis-C and HIV viruses is gaining favour in the country’s public health system. Nucleic acid testing (NAT), as the new technique is called, reduces the detection period for hepatitis-C from 50-plus days to five, hepatitis-B from 40 days to 10, and HIV from 10 days to just four. The equipment is manufactured by Novartis Diagnostics, and needs to be installed in clean, dust-proof labs.
The National AIDS Control Organisation (NACO) sees this as an important step towards reducing the transmission of the three viral diseases. This is because NAT is far more sensitive than other methods and can red-flag extremely low levels of viral material even before the body responds to the viral material by producing antibodies. Reducing the detection window can check the spread of the diseases.
“Treatment can begin sooner once the virus is detected at an early stage,” says Kabita Chatterjee, director of the blood bank at AIIMS, Delhi, where the test is conducted free. AIIMS has found the new test has an advantage over the ELISA test, which has a longer window period and cannot detect low levels of a virus. However, there is a huge difference in cost: ELISA costs just Rs 10; NAT costs Rs 800, but has the advantage of being able to confirm the presence or absence of all three viruses.
Private hospitals have already started using the test and many government hospitals will soon provide the test for free for blood donors. The AIIMS pilot study highlights that for just one sample of blood carrying the virus left undetected, three other persons stand the chance of getting infected. “We can detect the infection load from patients of thalassaemia, haemophilia and other blood-related diseases as these are the people who need blood transfusion frequently and often contract the other diseases as well, due to viruses not being detected,” says Dr Kanjaksha Ghosh, director of the Institute of Immunohaematology, Mumbai.
The test is mandatory for blood donors in many parts of the world, and health experts in the country feel the government should make it compulsory in India too, given the high prevalence rates of viral diseases. As many as 7.4 million blood donations are collected annually. Dr Anand Deshpande, consultant, transfusion medicine, at the P.D. Hinduja Hospital, Mumbai, says, “The test is a part of routine testing in 12 blood centres across the country. The government and various blood banks have already planned adoption and implementation of NAT to increase the availability of a safer blood supply.”
