Seroprevalence of hepatitis B and C in Nepal: a systematic review (1973–2017)

Introduction Hepatitis B and C represent an important co-infection for people living with HIV worldwide. Nepal wants to be part of the international mobilization for viral hepatitis elimination, and has pursued better understanding of the epidemic in its territory through scientific research. Methods We performed a systematic review of seroprevalence studies hepatitis B and C in Nepal following the PRISMA 2009 Flow Diagram. Results Fifty-four scientific publications and reports were selected for this review. Nearly a quarter of these documents have been issued in recent years and many are authored by non-governmental organizations in Nepal. The collective of information displays a wide range of alarming prevalence rates, particularly for girls and women survivors of human trafficking and a progressive participation of civil society in viral hepatitis epidemiology research in the country. Conclusion This paper presents a most complete review of hepatitis B and C and HIV co-infection prevalence studies in different population groups from 1973 to 2016. A comprehensive analysis of the epidemiology and apparent trends in public health research and policy making in Nepal are also addressed in this document. We expect this to be a most important tool for improvements in future interventions for both epidemics in the country.


Background
Viral hepatitis has become a leading cause of death and disability worldwide -estimated to be responsible for over 1.4 million deaths every year. Chronic viral hepatitis, mostly represented by the hepatitis B and C viruses infections (HBV and HCV, respectively), is a major cause of increasing events of high morbidity and mortality such as cirrhosis, end-stage liver disease and hepatocellular carcinoma. Both viruses are more easily transmissible than HIV [1].
The Sustainable Development Goals (SDG) establishes the year of 2030 as a desirable deadline for the end of many epidemics, including viral hepatitis. Nepal, a landlocked central Himalayan country in South Asia, has committed to the seventeen ambitious goals of SDG, and pursues to graduate from the least developed country rank by 2022.
Nepal already presented remarkable achievements in infectious diseases, particularly the HIV response [2][3][4]. However, the understanding of viral hepatitis impacts to the country is limited. There is no national plan devised for the elimination of viral hepatitis and hepatitis C has only been briefly mentioned in the National HIV Strategic Plan 2016-2021 (Nepal HIVision 2020) [5].
Multiple community-and facility-based seroepidemiological surveys for viral hepatitis and co-infections have taken place in Nepal since 1973 [6][7][8]. Studies have assessed different population groups mostly in urban areas of Kathmandu Valley and to a lesser extent in other development regions.
As new National Guidelines for Viral Hepatitis are being developed, the Joint United Nations Programme on HIV/ AIDS in Nepal (UNAIDS Nepal) understands this comprehensive review is a most welcome tool for future research. We expect this document to be useful for mathematical models, advocacy for key populations, improvements in public health policy, and setting priorities for successful elimination of hepatitis B and C.

Methods
We conducted a systematic review of seroprevalence studies of hepatitis B and C following the PRISMA 2009 Flow Diagram [9]. Our main sources of data for this research were: 1) PubMed (Medline), through the following search expression "(("Hepatitis B" [Mesh] OR "Hepatitis B, Chronic" [Mesh] OR "Hepatitis B virus" [Mesh] OR "Hepatitis B Surface Antigens" [Mesh] OR "Hepatitis B Antibodies"[-Mesh] OR "Hepatitis B" [Text] OR "Hepatitis C" [Mesh] OR "Hepatitis C, Chronic" [Mesh] OR "Hepatitis C Antibodies" [Mesh] OR "Hepatitis C"[Text]) AND ("Nepal" [Mesh] OR "Nepal"[Text]))"; 2) reports provided by the Government of Nepal (GoN); 3) reports authored by international agencies and non-governamental organizations (NGOs); and 4) personal correspondence to authors.

Study selection
Two researchers took part in all steps of the reviewing process. We assessed our initial search results for eligibility through title, abstract and full-text analysis. Duplicates were not identified, but two publications were found to be supplemental to previously evaluated studies. One review obtained during the search presented additional data for three studies unavailable in digital media. Personal correspondences were sent to authors to obtain additional information. We could not identify any repetition of datasets.
Publications were considered eligible for inclusion if they presented own and original data (absolute numbers or percentage) for any population group, Nepalese or residing in Nepal, at any given site and time for at least one of the following outcomes of interest: 1) hepatitis B seroprevalence, active infection or exposure; and 2) hepatitis C seroprevalence as detected by anti-HCV tests.
Selected publications were excluded if full-text material could not be retrieved, if published before 1981 and if abstract could not provide sufficient information for any of the three outcomes of interest.

Data extraction
The following data were then extracted from each eligible study included in this review: year of publication, population group, site, month and/or year of data collection, sample size, numbers/percentage of positive results for hepatitis B, C, HIV and syphilis; and authors' name.
Seven studies did not provide details of which tests were used to define active HBV infection [7,[10][11][12][13][14][15]. One study identified did not provide details about which tests were used to define seroprevalence of exposition to HBV [16]. We chose to display results for every study total population and for as many subgroups as possible. Figures were obtained through full-text analysis and personal correspondence with authors. All numbers were thoroughly revised.

Results
This review selection process is depicted in Fig. 1, as adapted from the PRISMA 2009 Flow Diagram [9]. Initial search expression resulted in ninety different records with no duplicates. Forty-two citations were excluded after title, abstract and full-text screening and one citation was found to be supplemental. One report from Asian Network of People Who Use Drugs (ANPUD), one from HEPA Foundation/United Nations Office on Drugs and Crime (UNODC), one from United Nations Development Program (UNPD), two from Nepal Red Cross Society (NRCS) and six from Ministry of Health of Nepal (MoH), including the Global AIDS Response Progress Report 2015 (GARRP), were added to the group of forty-eight eligible citations, resulting in fifty-nine documents.
Five records were excluded because full-text could not be retrieved and their abstracts did not have data on any of the three outcomes of interest. Three additional documents from 1987 to 1990, which were not listed in PubMed, were identified from a review and later included in the collective. Fifty-seven documents relevant to fifty-five relevant prevalence studies were selected for this review. Table 1 presents the collective of viral hepatitis prevalence studies with stratified population groups according to WHO key terms. Table 2 presents an analysis of the reviewed data and Cochran's Q tests performed by Weill Cornell Medical College in Qatar. Estimated prevalence and heterogeneity has been presented for five population groups: PWID, populations at intermediate risk, populations at low risk (general population), populations with liver-related conditions and special clinical populations [17].

Population groups
Candidates for blood donation account for just seven prevalence studies and yet represent approximately 90 % of the population evaluated for viral hepatitis in Nepal since 1973. This overwhelming presence of candidates for blood donation in seroprevalence studies does not contribute to the understanding of populations at increased risk of HBV, HCV and HIV co-infection in Nepal as they rarely present seroprevalence rates higher than 1 % [12,13,[18][19][20][21][22].
It is understood that people at increased risk of HBV, HCV and HIV co-infections should be properly represented in our review. We have succeeded to identify studies for most groups of interest: general population, children, adults, pregnant women, people who inject drugs (PWID), patients attending healthcare services, sexual and household contacts of people chronically infected by HBV, sex workers (SW), healthcare workers (HCW), migrant workers, refugees/displaced persons and survivors of human trafficking.
We found only one survey of viral hepatitis in lesbian, gay, bisexual or transgender population (LGBT), including men who have sex with other men (MSM); and another in people with history of incarceration. All collected documents only referred to drug use as injection and did not acknowledge people who use drugs (PWUD) or different methods of drug administration (e.g. smoking heroin). [23,24].
Children, adults and general population cohorts also present interesting ranges for figures of hepatitis B seroprevalence. Older age groups present higher values for HBsAg [20,34] and children born after vaccine implementation display reduced disease prevalence. [35].
Unfortunately, only one document presents viral hepatitis prevalence in LGBT population (MSM included), but it lacks important information on sample size and number of positive tests.
Exposure to hepatitis B virus, defined by anti-HBc (antibody against core antigen), has been assessed only in one key population -PWID, in two studies nearly twenty years apart. In 1996, more than 80 % of PWID had positive results for anti-HBc [25] and in 2015, when less than 45 % had positive results for the same marker [8].

Hepatitis C
One of the most important causes of morbidity [36] and mortality, particularly for people living with HIV (PLWH), [37] hepatitis C seroprevalence has been featured in thirty-one studies, in a total of approximately one million people in Nepal. Prevalence rates range from zero to more than 80%, with highest figures found in PWID (85.5 in males; 24.6 in females), [38] PLHIV (43.3) and patients with hepatocellular carcinoma (17.6). [27,38,39].
Regardless of key population status, different prevalence rates have been observed in males and females [40]. Statistically significant differences according to gender can be verified in studies by Shrestha            Age has been fundamental to the design of hepatitis C public health policies in many countries. It is known that age can relate to many factors in the epidemic: year of introduction of the virus, availability of tests and distribution of contaminated blood products, cumulative exposure (such as injection drug use, unprotected sexual activity across adult life), and status of harm reduction   [40,44].
HIV co-infection prevalence The first HIV prevalence study in Nepal dates 1989, [44] 1 year after the first case of HIV was detected in the country [45]. So far, eighteen prevalence studies also assessed at some time the HIV infection in their population, almost half a million people and roughly half of the population evaluated for HBV or HCV infection since 1985, the year of debut of anti-HIV ELISA tests. As stated previously for overall population, candidates for blood donation represent the majority of the population tested for HIV co-infection in Nepal in the fifty-five viral hepatitis prevalence studies of this review. Yet, regardless of age and/or gender subgroups, candidates for blood donation have failed to present HIV seropositivity rates above 0.2% [20,12,18], constituting themselves a population of low prevalence for HIV co-infection. This data must not considered a proxy for general population, as candidates for blood donation have shown to be a "poor control group for non-genetic studies of diseases related to environmentally, behaviourally, or socially patterned exposures", [46] but a reason to pursue further detection of viral hepatitis in priority populations.
As we evaluate the remaining studied population, we find that the highest rates of HIV infection found in this review do not belong to PWID, but sex trafficked girls and women, at an approximate 30% rate of infection in 2008 (74/246) [7). This is closely followed by PWID attending Recovering Nepal services, if accounted the participation of those with previously defined HIV status, with rates as high as 23.17% in 2015. Such findings are consonant with latest numbers of Family Health International data for HIV prevalence in PWID in Kathmandu (21% in 2009) [3] and increase of HIV and sexually transmitted infections in survivors of sex traffic, particularly for Nepalese girls and women [47][48][49].

Discussion
This review collects all available surveys performed in Nepal or with Nepalese population. It provides relevant information to policy makers, researchers and activists.

Developments of improved strategic information
It has been 44 years since the first viral hepatitis prevalence study took place in Nepal. Since then, sixty different publications, of which fifty-five are available in this review, have dedicated themselves to the better understanding of these epidemics.
Almost a quarter of these scientific publications and reports have been issued in the last 3 years. While there is still much to investigate, it is undeniable that Nepal's civil society organizations and academia have been successful in their struggle to improve the reactive approach to viral hepatitis and HIV, shaping public health policy and visibility of key populations.
Superior strategic information and overall engagement to the epidemics lead to additional victories: the inclusion of LGBT issues in government policies, the return of harm reductions strategy in 2007, increase in donor funding for the response to HIV, and stronger ties between emerging and existing networks of key populations and representatives, healthcare professionals, academia, UNAIDS and GoN [50][51][52][53][54][55]. Such echoing common voice for change lead to the preliminary discussion of National Viral Hepatitis Guidelines and negotiation of licensed generic drugs for hepatitis C treatment at a fraction of prices offered to other developing countries [41,[56][57][58][59]. This recent collective represents a cornerstone for viral hepatitis in Nepal.

Gaps and key populations
It would seem to be that the shared modes of transmission of viral hepatitis and HIV, and the resulting similar epidemiological profiles, could translate into one equally successful public health intervention for both epidemics. This is hardly the truth. Regardless of improvements in blood safety, availability of harm reduction services and assistance to sexually transmitted and reproductive tract infections, with significant drops in HIV prevalence since the last decade, many key populations sustain subpar decrease in hepatitis C numbers. Such is the case of PWID in Nepal: hepatitis C exceeds three times the HIV prevalence in several cohorts.
Since 2000, PWID, PLHIV, sex workers and LGBT have figured in no less than seventeen different viral hepatitis prevalence studies, almost a third of studies collected in this review, contributing without precedents to the national strategic information and deeper understanding of the response to public health interventions. Additional publications also developed initial data for other population groups such as refugees/misplaced persons and survivors of sex traffic.
Our research could not retrieve any studies regarding transgender population, male sex workers or incarcerated persons in Nepal.

Hepatitis B vaccine coverage and elimination of vertical transmission (EVT)
Hepatitis B is a highly contagious, yet preventable disease [60,61]. In recent years, many countries have chosen to scale up maternal and newborn care in order to secure a generation 'free of hepatitis B'.
Our review provided two studies depicting hepatitis B in infancy in Nepal. The first study states hepatitis B is responsible for approximately 5 % of the cases of acute hepatitis in children 0-15 years [14]. The second study describes observed benefits of hepatitis B vaccine introduction to children in Nepal in 2002. While no routine for hepatitis B immunoglobulin in prevention of vertical transmission has been implemented in Nepal, the rates of acute hepatitis related to HBV infection in children are quite different than the prevalence values of HBV in pregnant women (0.32%), an indicator that perhaps household exposure during infancy, and not mother-tochild transmission, is the reason for new but likely overlooked exposure during infancy (households).
Commercial vaccines for hepatitis B have been available worldwide since 1981 [62]. In Nepal, however, it has only been introduced in 2002. After fifteen years and despite recommendations issued by GoN, the country still struggles to provide appropriate vaccine coverage [35,63].
Official government reports state that from 2002 until 2009, third-dose hepatitis B vaccine coverage for children 12-23 months stood at approximately 80%. [63,64] World Health Organization (WHO) and United Nations Children's Fund (UNICEF) estimate improved coverage in 20,012 and 2013, slightly above 95%. [65] Such higher vaccine coverage numbers are not homogenous in Nepal -not all municipalities have immunization plans or appropriate structure at their disposal [63,64]. Moreover, the intervention requires timely birth-dose vaccination for a most successful response, [66] and faces many other obstacles [67].
Hepatitis B vaccine is available to healthcare workers (HCW) in many countries. In Nepal, HCW are featured in two studies as an alternative to controls, with HBsAg seropositivity rates of 1.38 and 1.69% [26,68]. These figures are lower than the ones presented by key populations, but still higher than those of candidates for blood donation. Further investigation reveals that HCW and students in Nepal have largely mishandled biosafety procedures while at high risk of exposure to the infective agent. Studies in tertiary care centers have shown frequent needle-stick and sharps-related injuries, and incomplete or fully ignored vaccination and post prophylaxis procedures [69][70][71].
Nevertheless, UNAIDS understands that the strengthening of the immunization plan and maternal health must be accompanied of a nationwide awareness campaign for HCW and future health professionals.

Community and the strengthening of health systems
Communities were the first responders to the HIV epidemic, nearly thirty years ago. They have continuously played an essential role in development of research, health services and shaping of public health policy worldwide, expanding their activities to sustainable and affordable vaccines and medicines for viral hepatitis.
Moreover, these collectives of advocates, researchers, clients or providers have the ability to work unisonous with marginalized populations, increasing the reach and quality of health systems and health services, often detecting overlooked issues such as stigma and discrimination. Whether leading research or promoting health services, civil society engagement improves awareness, prevention, diagnosis and retention in care. This has been the case of both viral hepatitis and HIV epidemic.
In Nepal, these initiatives are considered to be just as important as developments provided by academia, government and international agencies. It is clear that these endeavors provide a unique opportunity to fill critical gaps such as strategic information, low immunization coverage rates and elimination of mother-to-child and household transmission.

Conclusion
The present review illustrates different turning points in viral hepatitis and HIV co-infection epidemiology in Nepal. Since 1973, when the first study on viral hepatitis in the country was published, there have been many changes in the understanding of these epidemics.
These include the indirect effects of successful public health policies aimed towards HIV, such as the decrease of viral hepatitis prevalence in PWID, and their limitations, revealing overlooked population groups and issues in viral hepatitis that require public health policies of their own.
The review also allows one to witness the progressive scientific development by Nepalese researchers and institutions, and civil society representatives' participation. Such collaboration correlates with increased number of studies and sample sizes in recent years including the survey of key populations, and will be fundamental for the success of the National HIV Strategic Plan 2016-2021 and achieving the SDG by 2030.