Blood transfusion is an indispensable component of modern medical care and saves millions of lives every year in situations such as obstetric haemorrhage, trauma, major surgery, haematological malignancies and inherited disorders of haemoglobin. The World Health Organization (WHO) estimates that approximately 118.5 million blood donations are collected globally each year, with a substantial proportion coming from low- and middle-income countries where the demand for safe blood continues to outstrip supply (1). Despite its life-saving potential, blood transfusion is a well-recognised route for the transmission of infectious agents, collectively termed transfusion-transmissible infections (TTIs), of which human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV) and syphilis (caused by Treponema pallidum) are of major public health importance (2,3).

The transfusion of infected blood not only endangers the recipient but also creates a self-perpetuating chain of transmission in the community, as recipients may unknowingly transmit these infections further. A single unit of infected blood, when separated into components, can potentially infect multiple recipients, thereby amplifying the risk manifold (2). Post-transfusion hepatitis and transfusion-associated HIV infection carry serious consequences including chronic liver disease, cirrhosis, hepatocellular carcinoma and acquired immunodeficiency syndrome, all of which impose an enormous clinical, social and economic burden, particularly in resource-limited settings (3,4).

In India, screening of every unit of donated blood for HIV, HBV, HCV, syphilis and malaria is mandatory under the Drugs and Cosmetics Act, and national guidelines issued by the National AIDS Control Organisation (NACO) govern donor selection and testing protocols (4). India carries an intermediate endemicity for HBV, with an estimated HBsAg carrier rate of 2–4% in the general population, while the prevalence of HCV is estimated at 0.5–1.5% (5,6). Several hospital-based studies from different regions of India have reported wide variations in TTI seroprevalence among donors, with HBsAg positivity ranging from 0.6% to 2.5%, anti-HCV from 0.2% to 1.0%, HIV from 0.08% to 0.5% and syphilis from 0.1% to 1.6% (5–10). These variations reflect regional differences in disease endemicity, donor demographics, the proportion of voluntary versus replacement donors, and the sensitivity of screening assays employed.

The seroprevalence of TTIs among blood donors serves as a useful surrogate marker of the burden of these infections in the healthy adult population, since donors are apparently healthy individuals drawn from the community (7). Furthermore, longitudinal analysis of donor screening data allows blood banks to monitor trends over time, evaluate the effectiveness of donor education and selection strategies, and identify emerging threats to the blood supply (5,8). The WHO advocates the collection of blood exclusively from voluntary, non-remunerated, low-risk donors as the cornerstone of a safe blood supply, since numerous studies have consistently demonstrated a higher prevalence of TTIs among replacement and remunerated donors compared with voluntary donors (1,11,20).

Regular region-specific data are therefore essential for policy formulation and for benchmarking blood safety. The present study was undertaken to determine the seroprevalence of HIV, HBV, HCV and syphilis among blood donors at the blood bank of a tertiary care teaching hospital, to analyse trends over a five-year period, and to compare seroreactivity between voluntary and replacement donors.

Study design and setting: This was a retrospective, record-based, cross-sectional study conducted at the licensed blood bank (blood centre) of a tertiary care teaching hospital. The blood bank caters to the transfusion needs of the hospital as well as surrounding healthcare facilities and collects blood from both in-house donations and outdoor voluntary blood donation camps. Study period: Donor screening records from 1 January 2021 to 31 December 2025 (five calendar years) were retrieved and analysed. Study population: All blood donors (voluntary and replacement) who donated whole blood at the blood bank or at outreach camps during the study period and whose screening records were complete were included. Donors were selected according to the criteria laid down by the Drugs and Cosmetics Act and NACO guidelines (4): age 18–65 years, weight ≥ 45 kg, haemoglobin ≥ 12.5 g/dL, and absence of high-risk behaviour or deferrable medical conditions as ascertained by a structured donor questionnaire, pre-donation counselling and medical examination. Donors with incomplete records were excluded. Sample collection and serological screening: Approximately 5 mL of venous blood was collected from the pilot tubing of each donated unit into a plain vacutainer. Serum was separated by centrifugation and screened as follows: • HIV: Antibodies to HIV-1 and HIV-2 were detected using a fourth-generation ELISA kit (detecting both antigen and antibody), performed according to the manufacturer's instructions. • HBV: Hepatitis B surface antigen (HBsAg) was detected by third-generation ELISA. • HCV: Antibodies to HCV were detected by third-generation ELISA incorporating core and non-structural (NS3, NS4, NS5) antigens. • Syphilis: Screening was performed using the rapid plasma reagin (RPR) test. All ELISA runs included the manufacturer-provided positive and negative controls, and results were accepted only when kit validation criteria were met. Initially reactive samples were retested in duplicate with the same assay, and samples reactive on repeat testing were considered seropositive as per NACO strategy for blood-bank screening (4). Seroreactive units were discarded following standard biomedical waste management protocols, and reactive donors were notified, counselled and referred to the integrated counselling and testing centre (ICTC) or appropriate speciality clinic for confirmation and management. Data collection and analysis: Data on donor age, sex, type of donation (voluntary/replacement) and serological results were extracted from blood bank registers and the donor management software into a Microsoft Excel spreadsheet. Data were analysed using descriptive statistics; categorical variables were expressed as frequencies and percentages, and seroprevalence was calculated as the number of reactive donors per 100 donors screened. The chi-square test was used to compare proportions between groups, and the chi-square test for linear trend was applied to year-wise seroprevalence data. A p-value < 0.05 was considered statistically significant. Analysis was performed using SPSS version 26 (IBM Corp., Armonk, NY, USA).

A total of 24,850 blood donors were screened during the five-year study period. The majority were male (93.0%) and aged 18–30 years (54.3%). Voluntary donors constituted 73.0% of all donations (Table 1).

Table 1. Demographic profile of blood donors (N = 24,850)

Of the 24,850 donors screened, 412 (1.66%) were seroreactive for at least one TTI. HBV was the most common infection (1.00%), followed by HCV (0.25%), syphilis (0.22%) and HIV (0.19%). Co-infection with more than one marker was detected in 4 donors (0.02%), the commonest combination being HBV with syphilis (Table 2).

Table 2. Overall seroprevalence of TTIs among blood donors (N = 24,850)

Year-wise analysis showed a gradual decline in overall TTI seropositivity from 1.98% in 2021 to 1.38% in 2025, which was statistically significant on chi-square test for trend (p = 0.01). HIV seroprevalence declined significantly from 0.26% to 0.13% (p = 0.03). HBV, HCV and syphilis showed declining or stable trends that did not reach statistical significance (Table 3).

Table 3. Year-wise trend of TTI seroprevalence among blood donors (2021–2025)

Seroreactivity was significantly higher among replacement donors (2.41%) than voluntary donors (1.38%) (p < 0.001). This difference was consistent across all four markers (Table 4).

Table 4. Comparison of TTI seroprevalence between voluntary and replacement donors

The highest number of seroreactive donors belonged to the 31–40-year age group (2.02%), and seroreactivity among male donors (1.71%) was higher than among female donors (1.04%), though the latter difference did not reach statistical significance (p = 0.08) (Table 5).

Table 5. Age- and sex-wise distribution of seroreactive donors

Screening of blood donors provides a valuable window into the epidemiology of TTIs in the apparently healthy adult population and remains the mainstay of blood safety. In the present study, the overall seroprevalence of TTIs was 1.66%, which is comparable to figures reported from other Indian tertiary care centres, such as 1.09% by Makroo et al. from north India (6) and 2.62% by Pallavi et al. from south India (5), and within the broad range of 1–4% described in multiple hospital-based series (7–10). HBV was the predominant TTI in our study (1.00%), consistent with the intermediate endemicity of hepatitis B in India and with virtually all published Indian donor series, in which HBsAg positivity has ranged from 0.6% to 2.5% (5–8,10). The persistence of HBV as the leading marker underscores the large pool of asymptomatic chronic carriers in the community and reinforces the need for universal hepatitis B vaccination, which is expected to gradually reduce carrier rates in younger donor cohorts (6). The HCV seroprevalence of 0.25% observed in our study is similar to the 0.23–0.66% reported from Delhi and other centres (8,17), while the HIV prevalence of 0.19% is in keeping with the declining national HIV epidemic and mirrors reports from comparable settings (5,9,10). Syphilis seroreactivity of 0.22% was lower than the figures of 0.85–1.6% reported in some older Indian and African series (10,12), possibly reflecting changing sexual behaviour, widespread antibiotic use and improved donor selection. An encouraging finding was the statistically significant declining trend in overall TTI seropositivity and in HIV seroprevalence over the five-year period. Similar declining trends have been documented by Pallavi et al. in Mysore (5), Makroo et al. in New Delhi (6), Tessema et al. in Ethiopia (13) and Song et al. in western China (14), and have been attributed to intensified information–education–communication activities, stringent donor questionnaires, confidential unit exclusion, pre-donation counselling and the progressive shift towards voluntary non-remunerated donation (5,6,13,14). The significantly higher seroreactivity among replacement donors compared with voluntary donors in our study (2.41% vs 1.38%) reaffirms one of the most consistent observations in transfusion medicine literature (5,7,11,20). Replacement donors, often under family or social pressure to donate, may conceal high-risk behaviour, whereas repeat voluntary donors constitute a self-selected, counselled and repeatedly screened low-risk pool (11,20). This finding strongly supports the WHO recommendation that blood services should aim for 100% voluntary, non-remunerated donation (1,20). The preponderance of seroreactivity in the 31–40-year age group is noteworthy, as this economically productive and sexually active group also forms the backbone of the donor pool; similar age-related patterns have been reported previously (9,16). It must also be emphasised that serological screening, however well performed, cannot detect donations made during the immunological window period. Nucleic acid amplification testing (NAT) substantially shortens this window for HIV, HBV and HCV, and its wider implementation, along with centralised testing and quality assurance, would further reduce residual transfusion risk (3,6,20).

The overall seroprevalence of TTIs among blood donors in this study was 1.66%, with HBV being the most common marker, followed by HCV, syphilis and HIV. The significant declining trend in overall seropositivity over five years is encouraging and likely reflects improved donor education, counselling and selection practices. However, the persistently higher seroreactivity among replacement donors highlights the continued need to promote and retain voluntary, non-remunerated, repeat blood donors. Strengthening pre-donation counselling, universal hepatitis B immunisation, stringent donor selection and the adoption of sensitive screening technologies such as NAT are recommended to further enhance the safety of the blood supply.

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