Brief Reports

Brief Reports

Indian Pediatrics 1999;36: 1248-1250

Seroprevalence of Antibodies to Hepatitis A Virus among Children in Northern India

Rakesh Aggarwal, Sita Naik, S.K. Yachha, S.R. Naik

From the Departments of Gastroenterology and Immunology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow 226 014, India.
Reprint requests: Dr. Rakesh Aggarwal, Asso- ciate Professor, Department of Gastroenterology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow 226 014, India. E-mail: [email protected]
Manuscript received: May 10, 1999;
Initial review completed: June 10, 1999;
Revision accepted: July 12, 1999

Hepatitis A virus (HAV) and hepatitis E virus (HEV) are responsible for enterically-transmitted acute viral hepatitis. Infection with both HAV and HEV are endemic in developing countries. HAV infection is transmitted predominantly by close person-to-person contact(1). In endemic areas, HAV infection is common during childhood. In this age group, the infection is usually mild and asymptomatic, and induces anti-HAV antibodies, which confer life-long immunity against reinfection(1). On the other hand, HAV infections in adults are more often symptomatic and severe. It is generally believed that most residents of endemic areas are exposed to HAV infection by early adulthood and are therefore immune to it; if so, vaccination against HAV may have little role to play in these areas. HEV infection, on the other hand, appears to be transmitted predominantly through contaminated water(2) and person-to-person transmission is infre-quent(3). Exposure to this infection appears to be less frequent among children as compared to HAV infection(4).

Early studies of HAV seroprevalence in India showed that 90% of Indian children in the age group of 5-10 years had anti-HAV anti-bodies(5). This observation is of particular interest because of recent availability of an effective vaccine against HAV. However, more recent reports from our country show that anti-HAV antibody may not be as frequent in children and young adults as was previously believed(6-7). In light of these conflicting observations, we decided to study the preva-lence of anti-HAV among a group of northern Indian children.

Methods

Sera were obtained from 73 children (6 months to 18 years old) who had attended our institution for minor non-infective illnesses. These sera were tested for the presence of anti-HAV antibody using a commercially available immunoassay (Abbott), which was performed as per the manufacturer's instructions. Sera testing indeterminate were retested; those that tested indeterminate again were considered negative. Anti-HEV IgG status of these sera has been previously reported by us(8).

Relationship of anti-HAV antibody status with increasing age was studied by applying Chi-square test for trend to antibody prevalence in three different age groups, namely 0-5, 6-10, and 11-18 years.

Results

Of the 73 sera, 61 (84%) tested positive for anti-HAV, whereas 45 (62%) tested positive for anti-HEV. Anti-HAV prevalence rates were similar among boys and girls (34/38 and 27/35, respectively; p >0.05). Anti-HAV positivity rates in different age groups showed a progressive rise with age (Table I; p <0.02; Chi-square test for trend).

Table I^__ Prevalence Rates of Antibodies to Hepatitis A Virus Among Healthy Children in Different Age Groups.

Age group(years)	Number of study subjects	Anti-hepatitis A virus antibody positive* Number (%)
0-5	28	19 (68)
6-10	22	20 (91)
11-18	23	22 (96)

* Chi-squared test for trend; p <0.02

Discussion

Our data show that anti-HAV antibody prevalence in this cohort of children increased with age, and reached 96% by late childhood. Our data are in contrast to those reported recently from other Indian centers, which showed much lower anti-HAV positivity rates. In a study conducted in Mumbai, anti-HAV was detected in only 77.5% and 83.3% of children in the age groups of 6-10 and 11-15 years, respectively(6). Corresponding anti-HAV prevalence rates for these age groups among a subgroup of children belonging to middle and upper socioeconomic strata drawn from a private clinic were 75% and 65%, respectively, whereas those among children of lower socioeconomic stratum were 78.8% and 91.3%, respectively(6). Similarly, in a study from Delhi, anti-HAV antibody prevalence rate among 11 to 20 year old healthy subjects was only 39.8%(7), again being lower in persons with higher socioeconomic status than those with lower socioeconomic status (30.8% and 51.2%, respectively). Both these studies included children from larger cities of Mumbai and Delhi in contrast to the present group.

Differences between our data and those of others(6,7) may relate to differences in HAV epidemiology in different population groups. Our hospital, being a paying hospital, caters primarily to children belonging to middle and higher socioeconomic classes. A high anti-HAV prevalence rate in this group is therefore unlikely to be related to socioeconomic factors. Our data may thus suggest that children living in smaller non-metropolitan cities may have greater chances of exposure to HAV. This may be related to differences in water supply systems, population densities, playing and mixing habits of children, educational status of parents, etc. On the other hand, it is possible that, prevalence of anti-HAV antibodies in different regions of the country is different. Larger epidemiologic studies are necessary to elucidate the true reason for differences in prevalence of anti-HAV in different studies from our country.

Based on recent reports of relatively low anti-HAV prevalence in young adults in India, it has been suggested that hepatitis A vaccination may be indicated in our popula-tion(9). Our data indicate that these suggestions based on small studies from limited geographi-cal areas may not be true for the entire country. Our data thus emphasize the need for intensive, well-planned, population-based epidemiologic studies in different parts of the country; these alone will allow formulation of cost-effective strategies for the use of hepatitis A vaccines which have recently become available but are still quite costly.

References

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2. Krawczynski K, Aggarwal R. Hepatitis E. In: Schiff's Diseases of the Liver, 8th edn. Eds. Schiff ER, Sorrell MF, Maddrey WC. Philadelphia, Lippincott-Raven, 1999; pp 849-860.

3. Aggarwal R, Naik SR. Hepatitis E: Intrafamilial transmission versus waterborne spread. J Hepatol 1994; 22: 718-723.

4. Arankalle VA, Tsarev SA, Chadha MS, Alling DW, Emerson SU, Banerjee K, et al. Age-specific prevalence of antibodies to hepatitis A and E viruses in Pune, India, 1982 and 1992. J Infect Dis 1995; 171: 447-450.

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6. Dhawan PS, Shah SS, Alvares JF, Kher A, Shankaran K, Kandoth PW, et al. Seroprevalence of hepatitis A virus in Mumbai and immu-nogenicity and safety of hepatitis A vaccine. Indian J Gastroenterol 1998; 17: 16-18.

7. Das K, Kar P, Chakravorty A, Gupta S, Das BC. Is a vaccination program against hepatitis A needed in India? Indian J Gastroenterol 1998; 17: 158.

8. Aggarwal R, Shahi H, Naik S, Yachha SK, Naik SR. Evidence in favor of high infection rate with hepatitis E virus among young children in India. J Hepatol 1997; 26: 1425-1426.

9. Kar P. Hepatitis `A' virus epidemiology is changing in India. Trop Gastroenterol 1997; 18: 45-46.