SEROPREVALENCE OF TRANSFUSION-TRANSMITTED INFECTIONS AMONG VOLUNTARY BLOOD DONORS AT A TERTIARY CARE HOSPITAL

Objectives: Blood transfusion is an effective treatment for saving millions of lives. However, transfusion-transmitted infections (TTIs) hamper blood safety. To prevent transmission of these diseases, screening for infections is an essential step for blood safety. Methods: This was a retrospective cross-sectional study at the Department of Immunohematology and Blood Transfusion, Tirunelveli Medical College and Hospital, Tirunelveli, for a period of 6 years from January 2017 to December 2022. Data of the blood donors screened were retrieved and analyzed with the aid of screening register and seropositive donor register over 2 months (December 2022 and January 2023). Results: Among 53522 donors, 0.44% were seropositive for TTI (0.44%, n=233/53522) in which 99.57% (n=232/233) were male donors. Prevalence was more in 18–25 age group (39.91%, n=93/233). Hepatitis B virus (HBV) was the most prevalent microbe (n=144/53522) (0.27%). The prevalence of HBV showed a decreasing trend, while the prevalence of syphilis showed an increasing trend. The prevalence of human immunodeficiency virus, hepatitis C virus and malaria was unchanged. Conclusion: Seroprevalence and changing trends of TTI among blood donors reveal the prevalence of infections in the general population which gives an idea of disease burden on society. Education about confidential unit exclusion and implementation can help reduce transmission risk and wastage.


INTRODUCTION
Transfusion of blood and its components is one of the lifesaving procedures, in the integrated part of health-care delivery system.A transfusion-transmitted infection (TTI) is an infection by any pathogen that can potentially be transmitted in donated blood through a transfusion to a recipient.Important transfusion-transmitted pathogens are Human immunodeficiency virus (HIV), Hepatitis B virus (HBV), Hepatitis C virus (HCV), syphilis, Human T cell lymphotropic virus, Parvovirus B-19, Cytomegalovirus and malaria [1].
The goal of any transfusion service is to provide blood components that are safe for the recipient and pose minimal risk of TTI.Transfusion transmissible agents have certain characteristics such as persistence in blood for relatively long period of time, giving rise to carrier or latent state, causation of disease with long incubation period, ability to cause symptomatic infections and stability in cold stored blood [2].
Mandatory screening tests for TTIs such as HIV, HBV, HCV, syphilis, and malaria are done in most of the blood centers in India.Continuous monitoring of TTIs among the donor is vital for risk assessment, to minimize disease transmission and optimize donor recruitment strategies, and also to know the prevalence of these diseases in the general population since blood donors are usually healthy members of society [3,4].This study was aimed to assess the prevalence of TTIs among blood donors and analyze the changing trends of these infections.

METHODS
This was a retrospective cross-sectional study conducted from the 6-year data of voluntary blood donors who had donated between January 2017 and December 2022, at the Department of Immunohematology and Blood Transfusion, Tirunelveli Medical College Hospital, Tirunelveli, Tamil Nadu, India.The data were analyzed over a period of 2 months (December 2022 and January 2023) after obtaining approval from the Institutional Ethics Committee (TIREC number 20232574).
HIV and HCV antibodies were screened by third-generation enzyme-linked immunosorbent assay (ELISA) (replaced with fourth-generation ELISA kits from 2022).HBV surface antigens were screened by sandwich ELISA.Syphilis was screened by rapid plasma regain (RPR) kits while malarial parasite was screened by Leishman's staining of peripheral smear.
Data of the blood donors screened were retrieved with the aid of screening register and seropositive donor register.Basic information of donors including age, sex, occupation, number of previous donations, and details of seropositivity was recorded in a proforma sheet.Donors who were seroreactive in the mandatory screening for HBV, HCV, HIV, syphilis, and malaria parasite were recorded.These data were examined along with the total number of blood units collected during the study period.Seroprevalence of individual TTI was calculated for individual years and any change in prevalence over the years was analyzed.

Statistical analysis
Data were entered in Microsoft Excel and data analysis was performed using SPSS software version 21 (IBM, USA).Descriptive statistical measures, i.e., frequency and percentage were utilized to present the data.
While following the trends in seroprevalence of TTI across the years, there was a decrease in prevalence of hepatitis B from 0.35% in 2017 (n=33/9558) to 0.17% in 2022 n=17/10015).There was no change in the seroprevalence trends of Hepatitis C, HIV, and Malaria.There was an increase in seroprevalence of syphilis in the past 2 years (0.08%, n=7/9080 in 2021 and 0.08%, n=8/10015 in 2022) (Fig. 2).

DISCUSSION
Transfusion transmissible infections are a major threat to safety of blood worldwide.These organisms have a window period and are screened for their antigenic markers or the antibodies induced by them by various tests such as immunochromatography, ELISA, chemiluminescence, or nucleic acid testing (NAT).The risk of TTI has declined dramatically in high-income countries over the past two decades due to effective screening methods like NAT [5].However, it is not the same in developing countries where even chemiluminescent immunoassay is not present in all the blood centers.
The study was carried out to note the changing trends of the TTI among blood donors.Seroprevalence among blood donors helps to predict the prevalence in general public as blood donors come from general population.This knowledge gives an idea about disease burden on the society and also the basic epidemiology of these diseases in the community.
In the present study, overall seroprevalence rate was 0.44% which was similar to the results in the study by Sujatha et al. (0.55%) and Radhiga et al. [6,7].Even though there was a slight reduction in total reactive donors in the year 2020 (n=28/6625), the seroprevalence was 0.42% which was comparable to other years.The reduction in collection was due to the COVID-19 pandemic, which curtailed blood transfusion services worldwide.
The seroprevalence rate of HBsAg in the present study was 0.27% which was lesser than in the studies by Sujatha et [6][7][8].Hepatitis B is the most common TTI encountered in blood transfusion services with a long incubation period, latent period and long window period.In the present study, the seroprevalence of HBsAg in donors showed a decreasing trend from 0.34% in 2017 to 0.17% in 2022.
The prevalence rate of hepatitis C in the present study was 0.07%.This was similar to the prevalence found in the studies done by Radhiga et al. (0.04 %) and Dobariya et al. (0.09%) [7,9].Seroprevalence of HCV in donors showed a wavering trend with lower prevalence in the years 2019 (0.01%) and 2020 (0.03%) and higher prevalence in 2018 (0.11%) and 2021 (0.11%).All these donors were referred to medical gastroenterology department for confirmation and treatment.
In the present study, seroprevalence of HIV was 0.06% among donors, which was comparable to the studies by Dobariya et [6,[9][10][11].HIV seroprevalence was consistently lower across the years.This was due to better awareness among general public of the risk factors and better donor screening.
In this study, prevalence rate of syphilis by RPR was 0.028%, which was lesser than in the study by Radhiga et al. (0.07%) [7].Seroprevalence of syphilis which was negative showed a rise in the years 2021 and 2022 (0.08%).While donors did not inform of their risk behavior during pre-donation counseling, during counseling after seropositivity, many divulged their high-risk behavior such as multiple sexual partners and homosexual activity.They did not inform of their high-risk behavior pre-donation, as they donated in camps along with their friends.
In the present study, seroprevalence of malaria was 0.004% which was similar to study conducted by Negi et al. (0.002%) and Kumar et al. (0.006%) [8,12].Seroprevalence of multiple infections was 0.002% in this study, which was similar to the results in the study by Siraj et HBsAg 1.27%, HCV 0.32%, VDRL 0.01%, and malaria 0.02% and also noted increasing trend for all serological markers [14].

CONCLUSION
In the present study, while HBV prevalence was on the decline, the prevalence of HIV, HCV and malaria were consistent and syphilis showed a rising trend.Even though robust donor screening in separate counseling rooms help to defer donors with high-risk behavior, this study showed that this was difficult in crowded public camps.Education about confidential unit exclusion and public awareness campaigns about the risk of transmission of diseases through blood transfusion could curb the TTI.To minimize TTIs and provide safer blood and blood components, sensitive screening test such as NAT should be implemented.