Immune profiles of hepatitis A in patients with chronic liver disease across three major hospitals in Sri Lanka

INTRODUCTION

Chronic liver disease (CLD) is a progressive condition marked by the gradual decline of liver function for over six months due to chronic liver injury, leading to inflammation and, eventually, irreversible fibrosis. If untreated, it develops into cirrhosis, the disease's end stage.^[1] Globally, about 1.5 billion people were affected by CLD in 2017, with non-alcoholic fatty liver disease (NAFLD) (60%) as the leading cause, followed by viral hepatitis B (29%) and C (9%).^[2] The clinical presentation varies with disease progression. Early stages have nonspecific symptoms, while advanced stages manifest severe complications such as ascites, variceal bleeding, jaundice, and hepatic encephalopathy. Diagnosis is challenging, with liver biopsy as the gold standard, though non-invasive methods like serum biomarkers (aspartate aminotransferase, alanine aminotransferase, hyaluronic acid) and imaging techniques (ultrasound, magnetic resonance imaging) are commonly used for their greater sensitivity and specificity.^[3] Management requires a multidisciplinary approach addressing the underlying cause and complications. This includes antiviral therapy for viral hepatitis, nutritional support, avoiding hepatotoxic substances, and vaccinating against hepatitis A and B.^[4] Patients with CLD are at high risk of experiencing severe outcomes if they contract viral hepatitis, potentially leading to acute-on-chronic liver failure, a severe form of hepatic decompensation. Preventing viral hepatitis is therefore critical in managing CLD patients, and vaccination plays a significant role in this, particularly for hepatitis A and B, which are preventable through immunisation.^[5]

Despite the importance of vaccination, studies highlight inadequate vaccine coverage among CLD patients. In the United States, from 2013 to 2014, only 40% of adults with CLD had received the hepatitis A vaccine.^[6] A Sri Lankan study during the same period reported no hepatitis A vaccination coverage among adults with CLD.^[7] These findings underline the need for improving hepatitis A vaccination rates in CLD populations globally.

Viral hepatitis has emerged as a major public health problem across the globe. It causes considerable morbidity and mortality in the human population. Hepatitis A, B, C, D and E viruses are the major hepatitis viruses that cause viral hepatitis.^[8] Among them, only hepatitis A, hepatitis B and hepatitis D viral infections can be prevented by effective vaccination.^[8]

Hepatitis A virus (HAV) is a non-enveloped RNA virus from the picornavirus family, primarily transmitted through the fecal-oral route.^[9] It does not cause chronic disease but can lead to severe, and rarely fulminant, hepatitis. HAV infection is particularly common in regions with inadequate sanitation, where most children contract it early in life, usually without symptoms. Globally, regions such as South Asia and Sub-Saharan Africa are considered hyperendemic for hepatitis A, while countries like Western Europe and the United States report lower infection rates due to improved sanitation and widespread vaccination efforts.^[10] The Centre for Disease Control and Prevention (CDC) reports that hepatitis A accounted for 7,134 deaths globally in 2016, approximately 0.5% of all viral hepatitis-related deaths.^[11] Sri Lanka is classified as an intermediate endemic country for hepatitis A, with an estimated incidence of 15 cases per 100,000 population. While hepatitis A occurs sporadically in Sri Lanka, there have been significant outbreaks, including the largest in 2009 among the armed forces, which resulted in 13,477 cases.^[12] Limited studies on hepatitis A seroprevalence in Sri Lanka have provided valuable insights into the current situation. A study conducted in the Gampaha District, in western Sri Lanka in 2015-2016 reported an overall seroprevalence of 80.7% across all age groups.^[13] Similarly, a retrospective analysis at the Department of Virology, National Hospital Kandy, revealed an 88.8% seroprevalence in the central region during 2019-2021.^[14] These findings suggest that while many individuals have acquired immunity, there remains a need for ongoing vaccination efforts, particularly among vulnerable populations such as individuals with CLD.

HAV infection symptoms typically appear 14 to 28 days after exposure and range from mild to severe. They include fever, malaise, abdominal discomfort, diarrhea, and jaundice. Adults tend to experience more severe symptoms than children, with the risk of complications increasing with age. HAV infection is diagnosed through the detection of HAV-specific IgM antibodies in blood, while PCR testing can be used to detect HAV RNA if needed.^[9] The presence of HAV-specific IgG antibodies indicates serological evidence of immunity against the virus, either due to previous exposure or vaccination.^[11]

Although HAV infection is generally self-limiting and there is no specific antiviral treatment, supportive care is used to manage symptoms. Preventive strategies for hepatitis A include improving sanitation, ensuring a safe food supply, and vaccination.^[11] In Sri Lanka, where hepatitis A is endemic, a substantial portion of the population gains immunity early in life, reducing the need for widespread vaccination.^[12,13,15].

However, with improvements in sanitation, the seroprevalence of HAV IgG antibodies has declined, and the population is now more susceptible to infection. This highlights the ongoing importance of vaccination efforts, especially among vulnerable groups like those with CLD.

This study aimed to assess the seroprevalence of HAV immunity and evaluate hepatitis A vaccination coverage among patients with CLD attending three tertiary care government hospitals in Sri Lanka. By determining the proportion of naturally immune versus non-immune individuals, the study sought to inform targeted immunisation strategies, specifically, whether a selective vaccination approach for non-immune CLD patients may be more appropriate and cost-effective than implementing universal vaccination in this high-risk population.

MATERIAL AND METHODS

This study was a cross-sectional descriptive design and was conducted over a four-month period from February to June 2022. The focus was on patients diagnosed with CLD who were newly registered at gastroenterology clinics in three major government hospitals in three districts: National Hospital Kandy, Teaching Hospital Kurunegala, and General Hospital Kegalle in Sri Lanka. These hospitals serve as the main centres for the follow-up of CLD patients within their respective districts. Specimen processing and laboratory testing were carried out at the Department of Virology, National Hospital Kandy.

The sample size for this study was calculated using statistical formulas based on hepatitis A sero-prevalence rates. According to a prior study by Ariyarathna and Abeysena (2019), the sero-prevalence rate of hepatitis A was 89.7% among individuals aged 20 to over 80 years.^[16] Consequently, the final sample size for this study was determined to be 151 participants. Patients included in the study were those diagnosed with CLD by medical specialists in Gastroenterology at the relevant clinics using clinical, biochemical, imaging, and histopathological investigations. Each patient was given a unique identification number, which was used throughout the study to ensure accurate tracking of data. The inclusion criteria required patients to meet the case definition and provide informed consent, while those not meeting the criteria or refusing consent were excluded.

Recruitment of patients was carried out by the principal investigator during clinic registrations. Patients were identified through clinic records and other relevant medical records, with measures taken to avoid duplicate entries. Once identified, patients were informed about the study and given consent forms. Data collection involved the use of a questionnaire and the collection of venous blood samples. Demographic data such as age, gender, and area of residence were collected through patient interviews, while clinical data including duration of illness and vaccination status against hepatitis A and B were gathered from clinical records.

Blood samples were tested for hepatitis A immunity using chemiluminescence immunoassays on the LIAISON® XL Analyzer (Diasorin S.p.A, Italy). HAV-specific IgG antibodies were measured to assess immune status, ensuring high sensitivity and specificity. All procedures followed the manufacturer’s instructions and adhered to strict quality control measures.

Strict biosafety protocols were followed while handling potentially infectious clinical materials, and all biological waste was disposed of according to institutional protocols. Data collected was entered into an Excel spreadsheet, cleaned, and analysed using SPSS Version 25.0. Descriptive statistics such as frequencies and percentages were used for categorical variables, while mean and standard deviation were used for continuous variables.

RESULTS

Study participants were represented from three study settings. Both genders were included in the study sample. The sample size was 151 with a 100% response rate. The sociodemographic profile of the study participants was described at the initial stage and then the descriptive evaluation of anti-HAV IgG antibody detection was conducted.

1. National Hospital, Kandy

2. Teaching Hospital, Kurunegala

3. Teaching Hospital, Kegalle

Sero-prevalence of hepatitis A, and its associations

The majority of the participants tested positive for Hepatitis A IgG antibodies (n=120:79.4%).

The demographic characteristics of the study participants, including age and sex distribution, are summarised in Table 1. The association between HAV IgG seropositivity and participant age is presented in Table 2. Table 3 shows the relationship between hepatitis A immune status and gender of the study participants. The distribution of vaccination status and its association with hepatitis A immune status are detailed in Table 4.

Table 1: Age and sex distribution of the study participants.

Category	Frequency (N)	Percentage (%)
Age groups
< 40 yrs	9	6.0
41-50 yrs	12	7.9
51-60 yrs	47	31.1
61-70 yrs	68	45.0
>70 yrs	15	9.9
Gender
Male	89	58.9
Female	62	41.1
Total	151	100.0

Table 2: Association of HAV IgG with age of the study participants.

Age category	Positive (%)	Negative (%)	Total
<40	1(11.1)	8(88.9)	9
41-50	8(66.6)	4(33.4)	12
51-60	35(74.4)	12(25.6)	47
61-70	64(94.1)	4(5.9)	68
>71	12(80.0)	3(20.0)	15
Total	120	31	151

HAV: Hepatitis A virus

Table 3: Association of hepatitis A immune status with gender of the study participants.

HAV IgG	Positive N (%)	Negative N (%)	Total
Male	67(75.2)	22(24.8)	89
Female	53(85.4)	9(14.5)	62
Total	120	31	151

HAV: Hepatitis A virus

Table 4: Distribution of vaccination status and association of hepatitis A immune status with vaccination status.

	Vaccination status		Total
	Yes (%)	No (%)
Hepatitis A	1(0.7)	150(99.3)	151
HAV IgG	Positive 1	119	120
	Negative	31	31

HAV: Hepatitis A virus

The geographical locations of the study sites in Sri Lanka are shown in Figure 1, while the prevalence of HAV IgG among the study participants is presented in Figure 2.

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Figure 1:

Geographical locations of study sites in Sri Lanka.

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Figure 2:

Prevalence of HAV IgG among study participants. HAV: Hepatitis A virus

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The highest percentage of HAV antibodies was detected among the age group of 61 years to 70 years (N=64:94.1%). HAV antibody detection is significantly associated with age of the study participants (X²=34.6: p<0.001). The majority of the study participants below the age of 40 years were detected as negative for HAV antibodies (N=8: 88.9%).

The association of hepatitis A immune status and gender of the study participants were illustrated in Table 3. Females were presented more with HAV antibodies compared to males. The association between HAV antibody detection and gender was not statistically significant (OR=1.93:95%CI=0.82-4.54).

The prevalence of hepatitis A vaccination status (0.7%) is relatively low. Only one person was identified as vaccinated against hepatitis A among study participants. The vaccinated person was positive for HAV antibodies.

DISCUSSION

In Sri Lanka, CLD is increasingly driven by NAFLD, which has emerged as a significant global and national concern.^[17] NAFLD is a major cause of both CLD and hepatocellular carcinoma in the country. Ultrasound evidence indicates that more than half of middle-aged and elderly individuals in urban Sri Lanka are affected by NAFLD, with prevalence also observed in rural populations and children. Consequently, Sri Lankans face a heightened risk of CLD, with non-alcoholic steatohepatitis cirrhosis, a severe form of NAFLD, becoming the most common reason for liver transplant referrals.^[18] Traditionally, CLD in South Asia has been predominantly associated with viral hepatitis, particularly hepatitis B and C, along with contributions from hepatitis A. However, Sri Lanka stands out in the region for maintaining a notably low burden of chronic viral hepatitis. This positive trend is attributed to several public health measures, including national childhood immunisation with the hepatitis B vaccine, centrally managed state-regulated blood banks, safe handling of sharps, strengthened infection prevention and control practices in healthcare settings, low prevalence of intravenous drug use, and the limited use of intramuscular injections in clinical practice.^[17] Despite this low burden, hepatitis A infection remains a significant concern in patients with CLD, as it can exacerbate disease progression, leading to severe complications. These include an increased risk of cirrhosis and hepatocellular carcinoma, particularly in cases of co-infection with hepatitis B or C.^[11] Vaccination against hepatitis A is strongly recommended for all CLD patients to mitigate these risks.^[19] The hepatitis A vaccine is both safe and effective; however, its efficacy diminishes in advanced liver disease, underscoring the importance of early vaccination to ensure optimal immune response.^[20]

CONCLUSION

In summary, the study identified a high seroprevalence of HAV IgG antibodies (nearly 80%) among CLD patients in Sri Lanka’s Kurunegala, Kegalle, and Kandy districts. The findings suggest that assessing HAV immunity in CLD patients and selectively vaccinating non-immune individuals would be more cost-effective than universal vaccination, especially given the high natural immunity rate. This approach could provide a safer, targeted means of protecting CLD patients while conserving healthcare resources.