Childhood seroprevalence of hepatitis a in the United Arab Emirates

Introduction

Hepatitis A (HAV) is now in a transitional or intermediate endemicity in much of the world, and, paradoxically, these areas are at risk for rising disease incidence and large outbreaks. ¹ Although it is usually a self-limiting disease, human suffering may be considerable in areas of transitional endemicity.^1–3

The incidence of HAV is inversely related to socioeconomic development, and seroepidemiological studies show that the prevalence of anti-HAV antibodies in the general population varies from 15% to close to 100% in different parts of the world ² The Middle East is considered to be an intermediate to high endemic area, with documented prevalence rates of up to 80% by the age of 12 years^3,4

The aim of this cross-sectional study was to determine the prevalence of HAV A in childen aged <12 years in the United Arab Emirates (UAE) – a region with rapid modernization and improveming living standards and health-care facilities.

Methods

Over a period of 12 months (January 2004 to January 2005) 367 samples of serum were obtained from children aged between 1–12 years who presented to our hospital. Sampling was convenience non-random sampling. Paediatricians were asked to enrol any patient who had nonhepatic related consultations. Patients were recruited from both inpatient and oupatient services, as well as from the emergency room. All of the 367 samples were tested using a microparticle enzyme immunoassay for the detection of total antibody to HAV (IgG anti-HAV) in serum (AxSYM HAVAB 2.0, Abbot, Wiesbaden, Germany). This test has a sensitivity of 99.74% and a specificity of 98.96%. Informed consent was obtained from all the patients’ parents or guardians.

Results

Out of 367 children aged between 1–12 years (56% boys and 44% girls), 74 tested positive for IgG anti-HAV. The overall seroprevalence rate was 20.1% (95% confidence interval [CI] 16.4–24.6%). With subgroup analysis, the seroprevalence rate in children aged between 1–6 years (n = 196) was 10.2% (95% CI 6.7–15.2%) and in children aged 6–12 years (n = 171) it was 31.5% (95% CI 25.1–38.9%) (Table 1). There was no statistically significant difference between the sexes even though the proportion of boys was 15.1% greater the 6–12 year group (95% CI: 0.76–29.44%, P = 0.051).

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Table 1

Childhood seroprevalence of hepatitis A (HAV) in the United Arab Emirates

Age	Positives (IgG anti-HAV)/ Total	% of IgG anti-HAV (95% CI)
1–6 years	20/196	10.2 (6.7–15.2)
6–12 years	54/171	31.5 (25.1–38.9)
Total	74/367	20.1 (16.4–24.6)

UAE, United Arab Emirates

Discussion

Our study demonstrated that the seroprevalence rate in children of Abu Dhabi (UAE) aged between 1–12 years of age was 20.1%, confirming its transitional endemicity in this region. Selection bias included non-random sampling in an urban setting on only national patients (UAE passport holders, i.e. about one-third of the population). Even though the sample was from just one institution, our hospital is a tertiary centre which receives patients regularly from all the other six emirates within the UAE. The lower prevalence compared to children in other Middle Eastern countries most likely reflects the improving socioeconomic conditions and sanitation standards in the UAE.^4,5

In highly endemic countries where the lifetime risk of infection is greater than 90%, most infections occur early in childhood and exposure to HAV is almost universal before the age of 10 years. ² Most of these infections are asymptomatic and, thus, clinically apparent HAV is rarely seen in these countries and therefore large scale vaccination programmes are not recommended. ² In countries of intermediate endemicity, disease transmission occurs primarily from person to person in the general community, with periodic outbreaks. In these countries many individuals escape early childhood infection but are exposed later in life when clinical hepatitis occurs more frequently and presents a significant public burden.^1,2 In such areas, childhood immunizations may be considered as a supplement to health education and improved sanitation. Research to determine the cost effectiveness of routine HAV immunization in childhood needs to be undertaken.

Note The results of this work were published in part at the 4th World Congress of the World Society for Paediatric Infectious Diseases, Warsaw, Poland, 1–4 September 2005 [abstract]