Nucleic acid amplification test: Bridging the gap in blood safety & re-evaluation of blood screening for cryptic transfusion-transmitted infection among Indian donors

Abstract

Background & objectives: Nucleic acid amplification test (NAT) in blood donor screening not only detects window period (WP) donors but also those with chronic occult infections which are negative by routine serological screening. This study was conducted to determine the time trend of NAT positivity and seroprevalence of transfusion-transmitted infections (TTIs) through a period of six years and evaluate the strength of NAT as a supplementary test in identifying the cryptic carriers in blood donor population. Methods: A total of 1,01,411 blood donations were screened between January 2011 and December 2016 by the ELISA and individual donor (ID) NAT Procleix Ultrio Plus Assay. Additional molecular and serological assays were done on the NAT yield samples to differentiate the type of cryptic carriers. Results: NAT yields comprised 0.05 per cent (50/101411) of the total samples tested with a yield rate of 1/2028. Hepatitis B virus (HBV) contributed to 80 per cent of the total NAT yields and the rest 20 per cent due to hepatitis C virus (HCV). Majority of HBV NAT yields (75%) were from chronic occult donors and 25 per cent were WP donors. Both HBV and HCV NAT yields had a wide range of viral count. There was no HIV NAT yield. A significant decline in the prevalence rate of TTIs through the study period of six years was observed. Interpretation & conclusions: The cryptic infections found in blood donors increase the risk of TTIs. Blood screening by both serology and NAT can reduce this threat.

Prevalence of hepatitis B & C infections in prospective blood donors deferred due to history of jaundice

“…Technically, nucleic acid amplification technique (NAT) is the best method available to detect TTI and avoid the risk of transmission, especially in cases of occult infections (high sensitivity) as well as fresh infections (least window period) 19 , 20 . As per published Indian studies, the difference in prevalence rates by serology versus NAT (NAT yield) among jaundice-deferred donors is around 2.5-4 per cent 14 , 15 .…”

Seroprevalencia de infecciones hemotransmisibles en donantes de sangre

“…Estos resultados demuestran la existencia de una diferencia altamente significativa entre los resultados de las pruebas realizadas mediante serología y NAT, lo cual puede deberse a la fase clínica de la infección en cada individuo, ya que las pruebas serológicas buscan anticuerpos en su mayoría, que pueden ser el resultado de exposición previa al virus, mientras que las pruebas NAT buscan directamente el material genético del virus (ADN o ARN), el cual se encuentra en circulación durante la fase activa de la enfermedad. En el estudio desarrollado por Datta y colaboradores [17], afirman que pruebas no concordantes en VHB, VHC y VIH pueden deberse al periodo de ventana serológico, en donde existe una viremia que no puede ser detectada por las pruebas serológicas que se aplican a la tamización de donantes de sangre, y que constituyen un riesgo residual de transmisión de ITT, y de ahí la importancia de aplicar a las muestras de donantes tanto las pruebas serológicas como las que detectan material genético.…”

“…Los resultados no acordes encontrados en este estudio, podrían deberse a que la mayor cantidad de donantes captados en un banco de sangre intrahospitalario son de reposición, al igual que en la investigación de Rodríguez-Leiva [16] en el Hospital de Referencia de Paraguay, donde reportan que el 99,25 % de los donantes son por reposición, pero en su caso solo el 10,56 % presentaron serología reactiva. Varias investigaciones han demostrado que existe mayor riesgo de serorreactividad en donantes de reposición, y promueven la captación de donaciones voluntarias con la finalidad de minimizar la probabilidad de transmisión de agentes infecciosos en la sangre [17], sin embargo, es un tema que debe ser investigado.…”

Seroprevalence of Transfusion Transmissible Infections Among Voluntary Blood Donors at an Indian Hospital

“…It reduces the time for effective detection from 19 days of serological identification to 5 days for HIV, from 65 days to 7 days for HCV and from 38 days to 16 days for HBV. [15,29] It also detects donors with chronic occult infections, which are negative by routine serological screening methods. [29] However, the high cost of this technique is a limiting factor in India.…”

“…[15,29] It also detects donors with chronic occult infections, which are negative by routine serological screening methods. [29] However, the high cost of this technique is a limiting factor in India. Occasionally, HIV sero-yield donors may be nonreactive by NAT, possibly due to being aviraemic at the time of blood donation.…”