Against the backdrop of cases of HIV-infected blood over the last one and a half years reported across the country, experts have recommended advanced testing modalities like Nucleic Acid Testing (NAT) to combat the same.
National Aids Control Organisation (NACO) has recently revealed that 2,234 people across the country got transfused with HIV-infected blood over the same period, raising serious concern about blood safety.
Uttar Pradesh recorded the maximum number of transfusion transmitted HIV cases at 361 followed by Gujarat at 292 cases. Delhi grabbed the fourth position with 264 cases. Maharashtra has recorded more than 1,239 such cases over the last six years.
The main advantage of NAT screening, experts explain, is detection of new incident cases during the “window period” infections and identification of occult infections which can potentially be infectious but are not routinely picked up by the traditional tests like ELISA. Nuclear acid testing or NAT cuts down the HIV detection window period to six days from three months.
Says Dr. Dipanjan Haldar, consultant haematologist and haematoncologist, Wockhardt Hospitals, “To complement the use of NAT, there is also a need to recruit and retain new safe blood voluntary donors through an effective donor education, motivation, and recruitment strategy. This can help to expand the donor pool over time to meet the country’s needs as well as ensuring transfusion safety. All blood donations should therefore be screened using NAT.”
A recent study from Uttar Pradesh which has the highest reported incidence of transfusion transmitted HIV has revealed that the prevalence of HIV was twice in replacement donors as compared to voluntary donors. The study which compared the prevalence of various transfusion transmitted infections (TTIs) in voluntary and replacement donors also revealed the prevalence of hepatitis B and hepatitis C was more than five times higher in replacement donors as compared to voluntary donors.
However, with increasing awareness the percentage of voluntary donors is increasing in many parts of the country.
“Blood safety is a challenging task in India; with a high prevalence rate of HIV (0.29 per cent), HBV (2-8 per cent) and HCV (˜ 2 per cent) in general population. In our own study, 5003 donors were tested by both NAT and third generation ELISA, which is the standard test employed in most laboratories to screen for TTIs. Around 11 donors were found to be NAT-positive but ELISA-negative (NAT yield). Importantly no case of new sero-positivity was documented on the recipients of NAT tested blood over period of three years. Thus, NAT testing could provide the next large step in improving the safety of blood in India”, adds Dr Haldar.
TTIs are a key problem associated with transfusion of blood products worldwide. Infectious agents transmitted by blood products are very diverse and include hepatitis B (HBV), hepatitis C (HCV), human immunodeficiency (HIV-1/2), human T-cell lymphotropic (HTLV-I/II), Cytomegalovirus (CMV), Parvo- B19, West Nile (WNV) and dengue viruses. Trypanosomiasis, malaria, and Transmissible Spongiform Encephalopathy (TSE) also belong to TTIs.
There are various ways to reduce TTIs. The most important of these are appropriate donor selection, screening for serological infection markers and nucleic acid testing (NAT) by viral gene amplification. In India, family/replacement donors still provide nearly half of the collected blood.
“Concealing of medical history by captive, paid, or professional blood donors, who widely exist in developing countries like India pose a great threat to safe blood supply. To summarize, we need to follow the example of countries like South Africa which has implemented 100 per cent voluntary donation and encourage repeat donations from the same donor pool which has significantly helped in cutting down the TTIs. This can help to expand the donor pool over time to meet the country’s needs as well as ensuring transfusion safety. Besides this, all blood donations should be screened using NAT,” concluded Dr Haldar.