Seroepidemiology of hepatitis A virus in Hyderabad, South India

Abstract

The present study was carried to determine the prevalence of He-patitis A virus (HAV) IgM antibody among general population in Hyderabad since January 2002 to December 2011. A total of 4571 subjects were selected and divided into groups on the basis of age. The serum samples were screened for the presence of HAV IgM antibodies (anti-HAV IgM) using a commercially availa-ble enzyme linked immunosorbent assay (ELISA) kit. Of the 4571 serum samples, 4257 were negative and 314 (6.87%) were posi-tive for the HAV IgM assay. The disease predominance was more in males (212) with 67.51% compared to females (102) with 32.48%. Anti-HAV seroprevalence was measured for the following age groups: Early (≤20 years), Middle (21-40 years) and Late (≥41 years). Average age-wise IgM-anti-HAV positivity from 2002-2011 was 234 of 314 in ≤20 years, 74.52%), 73 of 314 (21-40 years, 23.24%), and 7 of 314 (≥41 years, 2.22%). The present study will provide insights to the recent epidemiologic features of HAV infec-tion in South India. [PUBLICATION ABSTRACT]

Headnote

Abstract

The present study was carried to determine the prevalence of He-patitis A virus (HAV) IgM antibody among general population in Hyderabad since January 2002 to December 2011. A total of 4571 subjects were selected and divided into groups on the basis of age. The serum samples were screened for the presence of HAV IgM antibodies (anti-HAV IgM) using a commercially availa-ble enzyme linked immunosorbent assay (ELISA) kit. Of the 4571 serum samples, 4257 were negative and 314 (6.87%) were posi-tive for the HAV IgM assay. The disease predominance was more in males (212) with 67.51% compared to females (102) with 32.48%. Anti-HAV seroprevalence was measured for the following age groups: Early (≤20 years), Middle (21-40 years) and Late (≥41 years). Average age-wise IgM-anti-HAV positivity from 2002-2011 was 234 of 314 in ≤20 years, 74.52%), 73 of 314 (21-40 years, 23.24%), and 7 of 314 (≥41 years, 2.22%). The present study will provide insights to the recent epidemiologic features of HAV infec-tion in South India.

Key words: HAV, ELISA, epidemiology

© 2012 Deccan College of Medical Sciences. All rights reserved.

Viral hepatitis, caused by any of the six hepa-totropic viruses, viz. hepatitis A virus (HAV), hepatitis B virus (HBV), hepatitis C virus (HCV), hepatitis D virus (HDV), hepatitis E virus (HEV) and hepatitis G virus (HGV), represents a major health problem worldwide. Among these, hepatitis A virus (HAV) is a most common causa-tive agent of human acute hepatitis and is consi-dered to be one of the epidemiologically important viruses. HAV is a positive-strand RNA virus be-longs to the family Picornaviridae, genus Hepatovi-rus1. HAV has a worldwide distribution, and ac-counts for more than 1.4 million cases of viral he-patitis annually2,3. Disease incidence varies over time and geography, with differences among coun-tries and even cities. Seroepidemiological data contributes significantly for a better understanding of the changing epidemiology of this infection. HAV infections are transmitted through feco-oral route, either by direct contact with an infected person or by consumption of contaminated water or food. Low Socio-economic status, high density housing and inadequate water treatment contribute to a pattern of high endemic in developing countries in which more than 90% of the population has ac-quired natural immunity before the age of 10 often from an asymptomatic infection. In such countries, explicit forms of hepatitis A are relatively rare with only exceptional severe cases4. Infected children who become infected are usually asymptomatic or with mild symptoms while infected adults with he-patitis A can develop fever, asthenia and jaundice.

The epidemiological pattern of hepatitis A infection is currently declining in many developing countries with improved sanitary conditions and hygiene practices. In recent years India and other transi-tional economies are showing a significant epide-miological shiftof HAV infection from high ende-micity to intermediate endemicity5,6. Increasing numbers of youth and adults, especially in urban developed areas, are now susceptible to HAV with considerable increase in morbidity with rare mortality.

The present study examines the current seropreva-lence of hepatitis A in South India and describes the seroepidemiological shiftover the past ten years. Useful epidemiological information can be drawn upon which new measures/strategies can be adopted that will prevent and limit the spread of hepatitis A.

Materials and Methods

From January 2002 to December 2011, serum samples were collected from 4571 hospitalized subjects for a variety of reasons at the department of gastroenterology in Deccan College of Medical Sciences, Hyderabad. In the outpatient department the subjects were identified with symptoms of jaundice, fever, loss of appetite, abdominal pain, scleral icterus, altered sensorium, encephalopathy and fatigue. A detailed history of each patient in-cluding travel history, blood transfusion, and food intake and water from outside sources was record-ed.

Subjects were categorized according to their age into three specific groups: early (≤20 years), middle (21-40 years) and late (≥41 years). Blood samples were collected from all the subjects and controls after taking the informed consent. Centrifugation was performed at 5000 rpm to separate the serum and stored at -80°C for further analysis. The study was approved by the institutional ethics committee of Deccan College of Medical Sciences, Hydera-bad. The age groups in both controls and subjects varied from 4 months to 75 years. All 4571 of the serum samples were tested using commercially available Hepavase MA-96 (anti-HAV IgM, Gene-ralbiologicals Corp, Taiwan Roc) for hepatitis A based on HRP conjugate.

In order to asses' co-infection of Hepatitis E Virus (the most common epidemic-causing virus in India) all the HAV positive samples along with controls were screened for anti-HEV IgM antibodies using EQUIPAR kit.

Results

Of the 4571 serum samples, 4257 were negative in the assay (used as controls) and remaining 314 (6.87%) samples were found to be positive for HAV IgM antibody (Fig 1, Table 1). The male predomin-ance was more with 67.51% (212 males) com-pared to females by 32.48% (102 females).

According to age groups ~74.52% of subjects in ≤ 20 years, 23.24% of subjects in 21-40 years and 2.22% of subjects in ≥41 years were seropositive for anti-HAV IgM antibody including both males and females. The HAV seroprevalence was found to be more in males in age groups ≤ 20 years and 21-40 years but was less in ≥41 years when com-pared to the females throughout the recent dec-ades (from 2002-2011).

In co-infection assay for Hepatitis E Virus, 28 sub-jects (8.91%) were found to be reactive for anti-HEV IgM antibodies in positive HAV patients and were highest in ≤ 20 years and least in ≥41 years of age groups in the years 2002-2011 (Table 2).

Discussion

Viral hepatitis continues to be a major public health problem in India and other developing countries. Ever since the first epidemics of hepatitis that had occurred in 1955 at Delhi7, several outbreaks of hepatitis have continued to occur. In India, availa-ble epidemiological data on HAV infection is li-mited. However, many recent reports have pub-lished the changing scenario for seroepidemiologi-cal patterns of hepatitis A infection in India8.

The World Health Organization (WHO) recom-mends for epidemiological and cost-benefit studies for HAV immunization2. Therefore, we decided to conduct a serological study on HAV infection pat-tern in different age groups form the year 2002-2011 in India and found 6.87% prevalence rate for anti-HAV IgM antibody. Our study observed high-est prevalence rate, during the year 2011, in ≤ 20 year age group which is similar to the situation prevailing in other developing countries9-11.

The risk of acquiring HAV infection is high for trav-elers to high HAV endemic areas in developing countries12. Seroprevalence of HAV infection va-ries among countries in Asia. The countries with low endemicity include Japan, Taiwan, Singapore and Hong Kong, whereas those with moderate en-demicity include Thailand, Sri Lanka and Malaysia. Countries with high endemicity for HAV infections include India, China, Nepal, Bangladesh, Pakistan, Myanmar and the Philippines13. The epidemiology of HAV infection over the last 20 yr shows that there were shifting patterns in the prevalence of antibodies to HAV throughout Southeast Asia and China from high to moderate (74.06% to 45.34%) and from moderate to low endemicity (45.34% to 3.01%)14,15. The epidemiological data on hepatitis A though limited from northern and western India, suggest that there has been a gradual shiftin the epidemiology of hepatitis A in India, like the Euro-pean countries16,17.

The distribution of anti-HAV seroprevalence by age group might reflect current hepatitis A status in various countries and regions18,19. HEV/HAV co-infection has been implicated as an important etio-logical agent for sporadic fulminant hepatic failure (FHF) in developing countries. Although HEV and HAV have a common route of transmission, these mixed infections could worsen the prognosis in patients with preexisting impaired liver function and may lead to acute hepatic failure (AHF) or FHF.

The present study will provide insights into the re-cent epidemiologic features of HAV infection in south India. Further community based surveillance studies are needed to define the endemicity of the disease.

Conclusion

The present study investigated hepatitis A virus (HAV) infection is shifting from early childhood (≤20) to adolescence 21-40 and adulthood ≥ 41 years due to occupational reasons and community living conditions. In our study we have also identi-fied prevalence of HAV and HEV co-infection, to prevent severe forms of disease when a subject with acute hepatitis A presents with an atypical clinical course such as hepatic encephalopathy. There is limited epidemiological data available on HAV infection from Hyderabad, Andhra Pradesh. In our study we have identified more prevalent HAV IgM Positivity in early age group. This study may help decision making on public health policies and vaccination strategies for the control of hepatitis A in India. In conclusion, more studies on sero-epidemiology of hepatitis A virus are required to evaluate the most appropriate age of HAV vaccina-tion in developing countries.

Acknowledgments: None

Conflict of interest: None

References

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