Prevalence of hepatitis-D virus in hepatitis B surface antigen-positive patients of India: A meta-analysis (research on behalf of ESGVH)

Abstract

BACKGROUND

Hepatitis D virus (HDV) infection accelerates liver disease progression in individuals with hepatitis B virus (HBV) infection, yet its true burden in India remains unclear. HDV depends on HBV for replication and is associated with rapid fibrosis, early cirrhosis, and increased hepatocellular carcinoma risk, making accurate prevalence estimates essential for clinical management and public health planning in endemic settings.

AIM

To estimate the pooled prevalence of HDV among hepatitis B surface antigen (HBsAg)-positive individuals in India and assess regional and methodological variations to inform national hepatitis control strategies.

METHODS

We systematically searched PubMed, Scopus, and Web of Science from inception to December 31, 2024 for studies reporting HDV prevalence in HBsAg-positive individuals in India, using laboratory-confirmed diagnosis. Eligible cross-sectional, cohort, or case-control studies were assessed for methodological quality using the Joanna Briggs Institute checklist. Pooled prevalence was calculated using a random-effects generalized linear mixed model with logit transformation. Heterogeneity was quantified with I² statistics, and publication bias was assessed by funnel plot inspection, Begg’s, and Egger’s tests.

RESULTS

Thirty studies, comprising a total of 5365 HBsAg-positive participants from multiple regions in India, met inclusion criteria. The pooled HDV prevalence was 5.05% (95% confidence interval: 2.37-10.41; I² = 93.5%, P < 0.0001), with reported rates ranging from 0% to 91.7%. Heterogeneity appeared related to study setting, population risk profile, diagnostic method, and geographic location. Begg’s test showed no significant asymmetry (P = 0.57), while Egger’s test indicated possible small-study effects (P = 0.006).

CONCLUSION

HDV co-infection affects approximately 5% of HBV carriers in India, representing a significant public health concern. Routine HDV screening, prioritization of high-burden regions, expansion of diagnostic capacity, and sustained HBV vaccination coverage are critical to reducing disease impact. Regional and population-based variation demands urgent implementation of standardized HDV testing protocols and targeted public health interventions in high-burden areas.

Key Words: Hepatitis D virus; Hepatitis B surface antigen; Prevalence; Co-infection; Epidemiology; Public health; Risk factors

Core Tip: This systematic review and meta-analysis provides the first comprehensive national estimate of hepatitis D virus (HDV) prevalence among hepatitis B surface antigen-positive individuals in India. Analyzing 30 studies with 5365 participants, the pooled HDV prevalence was 5.05%, highlighting substantial regional and methodological variability. The study identifies key drivers of heterogeneity, including diagnostic methods and population risk profiles, and underscores the urgent need for routine HDV screening, standardized testing protocols, and region-specific public health interventions to mitigate the burden of hepatitis B virus-HDV co-infection in India.

INTRODUCTION

Hepatitis D is a liver infection caused by the hepatitis D virus (HDV), also known as a satellite virus owing to its exclusivity in infecting people already infected with the hepatitis B virus (HBV)[1]. HBV is a significant global public health concern[2-4]. Co-infection with HDV significantly exacerbates liver disease outcomes, with most of the disease burden attributed to the chronic persistence of infection, principally cirrhosis and hepatocellular carcinoma[5,6]. HDV infection may occur as a co-infection (simultaneous infection with HBV and HDV) or as a superinfection (acquisition of HDV in individuals with pre-existing chronic HBV infection), which represent distinct clinical entities. Superinfection is generally associated with a more severe clinical course than co-infection, characterized by accelerated fibrosis, earlier onset of cirrhosis, and an increased risk of liver failure[7,8]. According to international guidelines, HDV infection is defined by the presence of anti-HDV antibodies in hepatitis B surface antigen (HBsAg)-positive individuals, indicating exposure to the virus, or by detectable HDV RNA, which confirms active viral replication[9]. HDV infection in individuals with pre existing chronic HBV infection leads to sevear clinical outcomes, like cirrhosis and liver failure.

Although HDV depends on HBV for replication, its geographical distribution differs partly due to the differences in transmission routes compared to HBV. HDV is mainly transmitted via the parenteral route, i.e., through blood or blood product exposure, while sexual transmission is infrequent and vertical transmission is rare[10,11].

Reported global prevalence estimates for HDV vary considerably, with some studies suggesting a burden of approximately 70 million infected individuals worldwide[12]. In contrast, the World Health Organization (WHO) estimates that about 5% of all HBsAg-positive carriers are infected with HDV, corresponding to roughly 12 million people globally[9]. Anti-HDV seroprevalence among HBsAg-positive carriers varies by geographical region, socio-economic status, and exposure to specific risk factors[13,14]. High-prevalence rates have been documented in Central Africa, South America, Mongolia, certain Pacific Island nations (e.g., Kiribati), southern Italy, and parts of the former Soviet Union[15-17]. A recent systematic review and meta-analysis identified particularly high HDV prevalence among populations with increased risk of exposure, including intravenous drug users, individuals engaging in unsafe sexual practices, and household contacts of HBsAg-positive persons[9]. Despite its clinical significance, the true prevalence of HDV infection in India remains unclear. Some studies, particularly from northern India, have reported relatively low rates among HBV-infected individuals[18], whereas others, such as a study from Uttar Pradesh, have found higher co-infection rates[19]. These discrepancies may reflect limitations in existing data, including small sample sizes, regional variation, and differences in diagnostic methods. Therefore, by analyzing available evidence we aimed to estimate the pooled prevalence of HDV infection among HBsAg-positive individuals in India, assess regional variability, and identify implications for public health policy.

MATERIALS AND METHODS

Study setting and ethical considerations

This study includes individuals from both rural and urban populations for inclusion in this systematic review. These populations may have different risk factors that could increase or decrease the risk of HBV infection. All studies included in this review had received appropriate ethics approval from their respective institutions or review boards at the time of their conduct. This research received approval from the Institutional Review Board, under registration number No. PhD/UDC/Regn./Dental/23/22. As this work is a systematic review and meta-analysis based on the anonymous use of previously published data that had already received ethical approvals, no additional ethics approval was required.

Search strategy

An extensive literature search was conducted in the PubMed, Scopus, and Web of Science databases up to December 31, 2024 to identify studies reporting the prevalence of HDV among HBsAg-positive patients in India. The search strategy combined relevant keywords with corresponding Medical Subject Headings terms, including “hepatitis D”, “hepatitis delta virus”, “Hepatitis B”, “hepatitis B surface antigens”, “prevalence”, “India”, and “co-infection”. A tailored search approach was applied for each database to ensure comprehensive coverage of relevant literature. The search focused on laboratory-confirmed diagnostic methods, including anti-HDV antibody testing and HDV RNA detection.

Inclusion and exclusion criteria

We reviewed the reference lists of included studies to ensure no relevant literature was missed.

The inclusion criteria: (1) Studies reporting prevalence data for HDV among HBsAg-positive patients in India, including sample size and diagnostic outcomes; (2) Cross-sectional, cohort, or case-control studies conducted in any region of India, covering both rural and urban populations; and (3) Studies employing laboratory-confirmed diagnostic methods, such as anti-HDV antibody testing or HDV RNA detection via polymerase chain reaction.

The exclusion criteria: (1) They lacked a clear specification of diagnostic methods or used outdated/non-standard diagnostic criteria for HDV; (2) They were reviews, editorials, or conference proceedings; and (3) They were conducted outside India or focused on Indian expatriates in other countries.

Assessment of methodological quality

This review adheres to the methodology and reporting guidelines established by the systematic reviews and meta-analyses (PRISMA) statement[20]. The review protocol has been submitted to the Centre for reviews and dissemination (CRD) and is registered under report number No. CRD42024612194 in PROSPERO (International Prospective Register of Systematic Reviews).

The quality of the included studies was evaluated using the Joanna Briggs Institute critical appraisal tool[21]. The assessment was guided by a tailored nine-question checklist allowing “yes”, “no” or “not applicable” answers. To maintain rigor and reduce bias, two reviewers independently evaluated each study separately. A third reviewer resolved disagreements through discussion and consensus. Studies scoring five or more out of nine were deemed to have good methodological quality and reliability.

Data extraction

Using a standardized, pre-tested data extraction form, two reviewers who performed the literature search independently extracted data from the included studies. Extracted variables included: Study characteristics (authors, publication year, location in India, study design, sample size); Patient demographics (age, gender, comorbidities); Diagnostic techniques (e.g., anti-HDV antibody testing or HDV RNA detection); HDV prevalence among HBsAg-positive patients, including subgroup analyses (e.g., by region, age, or risk factors such as intravenous drug use); Clinical outcomes and risk factors. Disagreements were resolved either through discussion or by consulting a third reviewer.

Statistical analysis

All analysis were conducted using the meta and metafor packages in R software[22]. The extracted data were systematically analyzed to estimate the pooled prevalence of HDV among HBsAg-positive patients in India. A random-effects model was applied to account for variability in prevalence across studies, estimating a pooled prevalence across different studies. Generalized linear mixed models with logit transformation were used to calculate study-specific effect sizes, as this method appropriately accounts for between-study heterogeneity and is recommended for meta-analyses of proportion data.

Between-study heterogeneity was assessed using the I² statistic and Cochran’s Q test[23] to differentiate true variability from random error. Thereby separating actual variation from random variance. Publication bias was evaluated using funnel plots for visual inspection and Egger’s test[24] to determine whether studies with significant results were more likely to be published. Forest plots were generated to visually display the heterogeneity in results, depicting individual study effect sizes and pooled prevalence estimates with 95% confidence intervals (CIs).

RESULTS

Study details

In this systematic review and meta-analysis, we identified 30 studies that investigated the prevalence of HDV among HBsAg-positive patients in India and met our inclusion criteria. The included studies were geographically diverse, covering multiple regions across the country, and examined HDV co-infection in the context of chronic HBV infection.

Search results

Database searches (PubMed: 85; Scopus: 149; Web of Science: 45) yielded a total of 279 records. After removing 40 duplicates, 239 records were screened by title and abstract. Of these, 174 were excluded- 173 deemed irrelevant, and one not in English. We successfully retrieved 65 full-text articles for eligibility assessment. Four articles were excluded at this stage: One due to improper design, two for being outside the study scope, and one due to unavailable full text. Afterwards, remaining 61 full-text articles were reviewed, and 31 were excluded due to insufficient data. Ultimately, 30 studies met the inclusion criteria and were included in the systematic review and meta-analysis (Table 1). Figure 1 shows the PRISMA flow chart of the literature search and selection of studies (Supplementary Tables 1-3).

Figure 1 The steps of the literature search and selection.

Table 1 Characteristics of the included studies[18,27,31-58].

Serial No.	Article title	Year of publication	Positive	Total sample tested	Positivity (%)	Ref.
1	A Hospital-based Retrospective Study on Frequency and Distribution of Viral Hepatitis	2014	0	818	0.00	Antony and Celine[31]
2	A study of hepatitis delta virus infection in patients with acute and chronic liver disease from northern India	1995	29	204	14.22	Singh et al[32]
3	Aetiology, clinical course and outcome of sporadic acute viral hepatitis in pregnancy	2003	6	413	1.45	Khuroo and Kamili[33]
4	An epidemic of hepatitis D in the foothills of the Himalayas in south Kashmir	1998	22	24	91.67	Khuroo et al[34]
5	Seroepidemiology of hepatitis delta virus infection in Pune, India	1992	6	235	2.55	Arankalle et al[35]
6	Delta virus infection in cirrhotics in a north Indian hospital	1993	4	40	10.00	Gupta et al[36]
7	Delta virus infections in and around Chandigarh, northern India: Evidence for endemicity	1987	11	81	13.50	Pal and Prasad[37]
8	Prevalence of hepatitis D virus infection among hepatitis B virus-infected individuals in India	2015	0	318	0.00	Jat et al[18]
9	Frequency of hepatitis B, C and D and human immunodeficiency virus infections in multi-transfused thalassemics	1992	9	18	50.00	Amarapurkar et al[38]
10	Hepatitis B and delta viruses in fulminant hepatitis	1990	20	32	62.50	Desai and Banker[39]
11	Hepatitis D infectivity profile among hepatitis B infected hospitalised patients in Calcutta	1998	2	60	3.33	Bhattacharyya et al[40]
12	Hepatitis delta virus infection among the tribes of the Andaman and Nicobar Islands, India	2005	8	170	4.71	Murhekar et al[41]
13	Hepatitis delta virus infection in Bombay	1992	124	331	37.46	Banker et al[42]
14	High prevalence of hepatitis delta virus among patients with chronic hepatitis B virus infection and HIV-1 in an intermediate hepatitis B virus endemic region	2014	22	450	4.89	Saravanan et al[43]
15	Low prevalence of hepatitis D (delta) virus infection in a nephrology unit in south India	1991	0	150	0.00	Thomas et al[44]
16	Magnitude and pattern of hepatitis B infection in clinically suspected infectious hepatitis at a tertiary care hospital in urban India	2014	4	24	16.67	Rajani and Jais[45]
17	Presence of acute hepatitis D infection in HBsAg positive cancer patients: A preliminary study from west Gujarat	2016	0	150	0.00	Patel and Goswami[46]
18	Prevalence of delta virus infection in high risk population and hepatitis B virus related liver diseases	1992	1	120	0.83	Amarapurkar et al[47]
19	Delta-hepatitis	1995	13	100	13.00	Ghuman and Kaur[48]
20	Prevalence of Hepatitis B & D Coinfection in Acute Active Viral Hepatitis in a Tertiary Care Hospital	2021	1	257	0.39	Nisar et al[49]
21	Prevalence of Hepatitis D virus antibodies in Hepatitis B patients treated at tertiary care unit at Jabalpur Central India	2021	8	372	2.15	Sonkar et al[50]
22	Prevalence of Hepatitis Delta Virus Infection among Hepatitis B Virus-Infected and Exposed Patients	2020	1	120	0.83	Ramachandran et al[27]
23	Prevalence of hepatitis viruses among chronic renal failure patients on hemodialysis in central India	2001	1	102	0.98	Jaiswal et al[51]
24	Prevalence of parenterally transmitted hepatitis viruses in clinically diagnosed cases of hepatitis	2005	1	28	3.57	Arora et al[52]
25	Profile of hepatitis B virus, hepatitis C virus, hepatitis d virus and human immunodeficiency virus infections in hemodialysis patients of a tertiary care hospital in uttarakhand	2013	1	12	8.33	Mittal et al[53]
26	Role of molecular techniques in the detection of HBV DNA & HCV RNA among renal transplant recipients in India	2000	2	13	15.38	Radhakrishnan et al[54]
27	Seroprevalence of HCV and its co-infection with HBV and HIV among liver disease patients of South Tamil Nadu	2010	12	512	2.34	Anbazhagan et al[55]
28	Seroprevalence of hepatitis D virus in patients with hepatitis B virus-related liver diseases	2005	26	123	21.14	Chakraborty et al[56]
29	Seroprevalence of hepatitis delta virus infection among subjects with underlying hepatic diseases in Chennai, southern India	2008	18	153	11.76	Saravanan et al[57]
30	Status of hepatitis viral markers in patients with acute and chronic liver diseases in northern India	1994	16	240	6.67	Irshad and Acharya[58]

HBV: Hepatitis B virus; HCV: Hepatitis C virus; HIV: Human immunodeficiency virus.

Meta-analysis of the prevalence of HDV

The pooled prevalence was estimated at 5.05% (95%CI: 2.38-10.41) based on 30 eligible studies from across the country. The studies were highly heterogeneous (I² = 93.5%, τ² = 4.2224, P < 0.0001); therefore, a random-effects model was utilized (Figure 2). The studies included in the review reported prevalence rates that varied widely, ranging from 0.00% to 91.67%. Subgroup analysis by region (random-effects model) revealed notable variation in HDV prevalence across India. The highest pooled prevalence was observed in South India (11.40%; 95%CI: 1.14-59.04), followed by East India (8.85%; 95%CI: 5.48-13.99) and West India (7.31%; 95%CI: 1.52-28.64). Central India reported a moderate prevalence of 5.21% (95%CI: 1.01-22.87), while North India exhibited the lowest pooled prevalence at 2.76% (95%CI: 0.96-7.66) (Figure 3). Substantial heterogeneity was observed across all subgroups, with I² values ranging from 71.5% to 95.4%, indicating considerable inter-study variability (Q range: 3.51-281.06) (Supplementary Tables 4 and 5).

Figure 2 Forest plot. Forest plot of prevalence estimates (pooled: 5.05%, 95% confidence interval: 2.37-10.41; random-effects model) showing substantial heterogeneity (I² = 93.5%, τ² = 4.2224, P < 0.0001) across 30 regional studies. CI: Confidence interval.

Figure 3 Regional prevalence of hepatitis D virus in India. CI: Confidence interval.

Assessment of publication bias using quantitative methods produced conflicting results. Begg’s test was non-significant (P = 0.57), whereas Egger’s test suggested small to moderate-study effects (P = 0.006) (Figure 4). However, Barker (2021) notes that these tests, and corresponding funnel plots, were originally developed for comparative studies and rely on assumptions that do not hold in proportional meta-analysis, where “positive” results lack a clear definition. Accordingly, Barker recommends qualitative assessment of publication bias in prevalence studies[25].

Figure 4 Funnel plot of logit-transformed proportions vs standard errors. Begg’s P = 0.57; Egger’s P = 0.006, showing moderate symmetry with potential small-study effects at higher standard errors.

DISCUSSION

Our meta-analysis of 30 studies conducted across India found a pooled prevalence of 5.05% (95%CI: 2.38-10.41) HDV infection among HBsAg-positive individuals. This estimate is broadly consistent with global findings. For example, a recent worldwide meta-analysis reported a HDV prevalence of approximately 4.5% among all HBsAg-positive individuals[19], while other studies have estimated prevalence at around 5%, corresponding to roughly 12 million cases globally[26].

In the context of India, with an estimated 40 million people living with HBV, even a mid-single-digit co-infection rate represents a substantial public health burden. A prevalence of 5.05% implies that nearly 2 million individuals in India may be living with HDV, the majority of whom are likely undiagnosed. This is of particular concern given that HDV/HBV co-infection is associated with a more aggressive disease course, with approximately 70%-80% of patients developing cirrhosis over several decades[26].

Prevalence estimates in individual Indian studies vary widely, from 0% to as high as 91.7%, reflecting a highly heterogeneous epidemiological landscape. This variability is likely influenced by regional differences in HBV prevalence, population-level risk factors, vaccination coverage, and access to healthcare, as well as by differences in study design, sampling strategies, diagnostic assays (anti-HDV antibody vs HDV RNA), and the time period of data collection. Reports span diverse locations including Mumbai (1990), Pune (1992), Chandigarh (1995), New Delhi (1996), Kolkata (1998), Haryana (2005), Andaman and Nicobar Islands (2005), Chennai (2008), Uttarakhand (2013), Lucknow (2015), and Gujarat (2016)[27]. Despite this heterogeneity, the pooled prevalence of approximately 5% positions India within the intermediate endemicity category. While this figure is slightly higher than the global average, it underscores the need for region-specific surveillance and targeted HDV control strategies rather than a uniform national approach.

Globally, HDV prevalence varies substantially across regions. Historically high rates have been documented in Eastern Europe, Central Asia, the Middle East, sub-Saharan Africa, and the Amazon Basin[28,29]. For example, Mongolia, Uzbekistan, Kyrgyzstan, and the Pakistan/Punjab region of India report some of the highest burdens worldwide[28]. In contrast, much of Western Europe and North America now report prevalence rates below 2%, largely due to long-standing HBV control programs[28,29]. Compared with hyperendemic countries such as Mongolia, where prevalence can exceed 10%-20%, India’s rate is moderate. However, due to the size of India’s HBV reservoir, the absolute number of HDV cases remains considerable-similar to the challenges faced by other low- and middle-income countries with localized high-prevalence pockets within broader HBV epidemics.

Over the past few decades, global HDV prevalence has declined in many regions, primarily due to widespread HBV vaccination and improved medical safety practices[29]. Italy, once highly endemic, reduced its HDV prevalence from over 20% in the 1980s to under 10% by the late 1990s following universal HBV immunization and public health interventions[29]. Comparable declines have been reported in China, Iran, and other Asian countries after implementing birth-dose HBV vaccination[28,29]. In India, the introduction of HBV vaccination into the universal immunization program in 2011[30] may gradually reduce HDV incidence in younger cohorts; however, measurable effects will require long-term surveillance. Persistent HDV hotspots suggest the need for targeted interventions.

Lessons from global experience, such as Italy’s vaccine-driven decline, Pakistan’s targeted screening initiatives, and the inclusion of HDV in the WHO hepatitis elimination strategy are highly relevant. The 2030 WHO targets for viral hepatitis explicitly recognize HDV infection, underscoring the need for integration into national policies[28]. In India, aligning with this agenda would involve incorporating HDV screening into existing hepatitis programs, particularly in high-prevalence regions and among patients with advanced liver disease.

From a public health perspective, our findings highlight the urgent need to address HDV in India and similar endemic settings. Although HDV infects a minority of HBV carriers, its impact on disease progression and prognosis is disproportionately large. Current WHO and European Association for the Study of the Liver guidelines recommend screening all HBsAg-positive individuals for anti-HDV antibodies[28]. Incorporating routine HDV testing into India’s National Viral Hepatitis Control Programme could enable earlier diagnosis, closer monitoring, and timely management. This would be particularly valuable in guiding prognostic counselling and access to antiviral therapy, including emerging agents such as bulevirtide where available.

Ultimately, HDV control is intrinsically linked to HBV prevention. Strengthening HBV vaccination, especially birth-dose coverage and catch-up immunization, remains the most effective strategy, as HDV cannot establish infection without HBV. Complementary measures such as harm reduction for people who inject drugs, safe blood transfusion and injection practices, and expanded HBV screening will further contribute to reducing HDV transmission.

Limitations

The interpretation of our pooled estimate should be approached with caution, given the extremely high heterogeneity across the included studies (I² = 93.5%), which significantly limits the generalizability of the findings.

Several factors likely contribute to this variability: First, population differences: Some studies targeted high-risk or symptomatic groups (e.g., patients with cirrhosis, hepatocellular carcinoma, or high-risk behaviors) in whom HDV prevalence is expected to be higher, while others sampled general HBsAg-positive carriers, often asymptomatic. For example, patients with advanced liver disease or those attending hepatology clinics have been reported to have HDV rates of up to approximately 16%[19], whereas community-based screenings often yield much lower rates.

Second, geographic variation: India’s vast and diverse regions differ in HBV epidemiology, healthcare access, and vaccination coverage. Some areas have historically reported high HDV burdens[28], while others show consistently low prevalence.

Third, temporal and methodological factors: Older studies conducted before the implementation of widespread HBV vaccination may overestimate current prevalence. Furthermore, differences in diagnostic approaches (anti-HDV antibody serology vs HDV RNA detection; commercial kits vs in-house assays) likely influenced case detection rates. Small sample sizes in certain studies may also have exaggerated extreme prevalence values particularly in case series from high-risk cohorts.

Taken together, these factors suggest that the pooled estimate reflects the presence of HDV infection in India at a non-zero but non-uniform rate, rather than indicating a consistent risk level nationwide. This extreme heterogeneity highlights significant knowledge gaps and underscores the need for more systematic, community-based studies to assess the true prevalence of HDV beyond tertiary care settings. Mapping regional and demographic patterns (e.g., age, gender, co-infections) would help direct resources more effectively. In the meantime, health authorities should operate under the assumption that HDV is not negligible. At minimum, clinicians managing HBV patients should consider HDV co-infection, and public health programs should integrate HDV into screening, awareness, and prevention strategies. With new diagnostic tools and emerging therapies, earlier detection could meaningfully improve patient outcomes.

CONCLUSION

In India, 5.05% of HBsAg-positive individuals are co-infected with HDV a prevalence slightly above the global average but representing a considerable absolute burden given the size of the HBV reservoir. Marked heterogeneity across regions and populations underscores the need for targeted surveillance and standardized HDV testing, particularly in high-risk groups. Integrating HDV screening into national hepatitis programs and reinforcing HBV vaccination and prevention strategies remain essential to curb transmission and improve long-term liver health outcomes. Aligning these measures with the WHO 2030 viral hepatitis elimination targets will be critical to reducing the clinical and public health impact of HDV in India.

ACKNOWLEDGEMENTS

We are grateful to the ESCMID study group for Vital hepatitis (ESGVH) chair for the constant support during the study and agreeing to support in the publication process.