Seroepidemiology of hepatitis B virus (HBV) and hepatitis C virus (HCV) and relationship to alanine transferase (alt) in saudi workers at yanbu industrial city.

OBJECTIVES: To study the epidemiology of Hepatitis B virus (HBV) and Hepatitis C virus (HCP) in a relatively new industrial community in Yanbu, and to find out whether any relationship exists between increased serum Alanine Transferase (ALT) and HBV infection.
METHOD: A group of Saudi male workers (n=332) (mean age = 32 years) were screened for Hepatitis B core antibody (anti-HBc), Hepatitis B surface antigen (HBsAg), Hepatitis C virus antibody (anti-HCV), and Alanine Transferase (ALT) level and the results were correlated with age and marital status.
RESULTS: Overall, the prevalence of anti-HBc, HBsAg, and anti-HCV were 23.2%, 7.7% and 0.6% respectively. Age-related HBsAg carrier rates were 7.8%, 6.4% and 9.4% for age groups 18-20, 21-30 and over 30 years respec-tively. Anti-HBc positivity rates lucre 7.8%, 24.3% and 23.1 M for the same age groups. Anti-HCV was positive in only two cases (0.6%) of all subjects. Con-sidering marital status, HBsAg and anti-HBc positivity rates were 7.8% and 20.5% for single subjects compared with 7.4% and 24.5% for married subjects (P=> 0.5 and > 0.5). Twenty-two percent of all subjects had ALT levels above 35 U/L with no correlation between the increase of ALT and anti-HBc or HBsAg positivity.
CONCLUSIONS: THE FINDINGS OF THIS WORK: (1) Support the notion of relatively low prevalence of HCV in the Saudi Population as compared to HBV. (2) Provide clues regarding possible routes of transmission of HBV in Saudis that may help in vaccination policies for control of HBV infection. (3) Emphasize the fact that ALT level is an independent factor of HBV infection, and (4) Signify the need to screen industrial workers fir non-viral causes of liver disease.

INTRODUCTION

Saudi Arabia is considered an area of endemic HBV infection. By adult age, 7% of the population has HBsAg and about 70% has one or more HBV markers.12 The epidemiology of HBV in Saudi Arabia has largely been established. Probably no further large-scale studies are needed to determine the prevalence of HBV in the country.

Studies on the prevalence and epidemiology of HCV infection in Saudi Arabia have also been conducted3–7 but further studies are still needed. Also still warranted are studies on the epidemiology of HBV in areas which have not yet been screened. Earlier studies on the major modes of transmission of HBV have justified and led to the establishment of a national mass neonatal HBV vaccination programme in Saudi Arabia in October 1989 as a part of the Expanded Programme of Immunization (EPI) following a Royal decree in 1988.8

Such a vaccination programme should eventually lead to the control of HBV infection in Saudi Arabia, however, questions on expanding the HBV vaccination programme to include other population groups have occasionally been raised, warranting the need for more understanding of the major modes of transmission of HBV in different population groups. This study represents an effort to address these concerns.

MATERIAL AND METHODS

Over a period of three months during 1994, Saudi males working in Yanbu industrial city and listed as potential blood donors were randomly selected for this study. Each subject completed a brief questionnaire with personal data that included age, nationality, sex and marital status.

Blood was collected from each subject and serum separated within 1 hour and analyzed freshly for ALT level. Aliquots were stored at -70°C until further serological analysis. ALT was measured using an International Federation of Chemistry recommended reagent (Boehringer: Mannheim, Germany) on a Hitachi chemistry analyzer. HBsAg, anti-HBc, and anti-HCV were measured using commercial enzyme immunoassays (for anti-HCV, second generation enzyme immunoassay-Elisa) from Abbott Laboratories (Chicago, USA).

Statistical analysis of the results, where applicable, was performed by constructing contingency tables and calculating the chi-squares (with Yates correction when applicable).

RESULTS

The prevalence of anti-HBc was 23.2% (77/332) reflecting mostly the overall exposure rate to HBV infection in this group of the study. HBsAg carrier rate was 7.7% (25/332). The anti-HCV prevalence rate, however, was approximately 0.6% (2/332), which is comparatively much lower than the HBV infection rate.

Age-specific analysis of these results, shown in Table 1 and Figure 1, indicated an anti-HBc prevalence of 7.8% (1/13) for the age group 18-20 years, 24.3% (49/202) for the age group 21-30 years and 23.1% (27/117) for the age group over 30 years. The age-specific prevalence of HBsAg was 7.8% (1/13) for age group 18-20 years, 6.4% (13/202) for the age group 21-30 years, and 9.4% (11/117) for the age group over 30 years.

Table 1

Distribution of HBV exposure and carrier rates by age and marital status

Figure 1

Age related HBV exposure and carrier rates

Categorizing the subjects by marital status (Table 1 and Figure 2), the anti-HBc prevalence rate was 20.5% (21/102) and 24.5% (56/230) while the HBsAg prevalence rate was 7.8% (8/102) and 7.4% (17/230) for single and married subjects respectively.

Figure 2

HBV exposure and carrier rates in relation to marital status

Assessment of ALT as a marker of dis-turbed liver in relation to HBV infection is summarized in Table 2. ALT levels higher than 35 U/L were found in 22% (73/332) of all subjects. At a cut-off value of 45 U/L, high ALT levels were found in 15% (51/332) of the subjects. ALT values higher than 70 U/L were found in 4.5% (15/332) of all subjects. Categorizing the subjects into two groups of normal (<35 U/L) and high ALT level, anti-HBc positivity rates were 23.5% (61/259) and 22% (16/73), and HBsAg carrier rates were 7.7% (20/259) and 6.8% (5/73) for both groups respectively. Using the 70 U/L of ALT as a cut-off, anti-HBc was positive in 40% (6/15 of subjects with ALT > 70 U/L compared to 22.4% (71/317) of subjects with ALT < 70 U/L. HBsAg was also positive in 20% (3/15) of subjects with ALT > 70 U/L compared to 6.9% (22/317) of subjects with ALT < 70 U/L.

Table 2

Distribution of HBV exposure and carrier rates by ALT level

DISCUSSION

During the last 15 years, various studies have been conducted in Saudi Arabia to examine the epidemiology of HBV and HCV among other hepatitis viruses and their relationship to liver disease in the Kingdom. A large volume of data has been collected by analysis of blood donors, school children, and outpatient populations from urban and rural areas all over the country.9–17 The average overall prevalence of HBsAg in Saudi Arabia was estimated to be about 8.3% which puts the Kingdom among the highly endemic areas in the world. The HBV exposure rate was estimated to range from 30% to 80% in different regions of the Kingdom.1 Our results of an HBsAg carrier rate of 7.7% and anti-HBc positivity rate of 23.2% support the nationally estimated rates of HBV infection through the 1990s.

The overall prevalence of anti-HCV in this group was 0.6%. Al-Mofarreh3 et al and Fathalla6 et al reported a similar low incidence of anti-HCV (1.24% and L 15%,) among Saudis in Riyadh and Dammam respectively. The relatively low number of subjects did not help meaningful epidemiological study for HCV in this group.

Studies on the transmission routes of HBV infection in Saudi Arabia demonstrated that perinatal transmission plays a minimal role, if any, in the transmission of HBV and that HBV infection occurs mainly horizontally with a first peak during the preschool childhood age and a second peak around the early adulthood ages of 20-30 years.9–131819

Our results of age-specific HBV infection fates continue to suggest a peak of HBV infection early in life, before 18 years, contributing for the most part to the establishment of the HBsAg carrier status in the population. This early peak is followed by a second peak of HBV infection during the early adulthood ages of 20-30 years.

Folk traditions in Saudi Arabia like circumcision by folk practitioners, “hijama,” skin cautery20 and head shaving with non-disposable razors, are potential contributing factors to the transmission of HBV in the Kingdom. “Hijama” is letting blood by incising the skin, mostly on the back. Heterosexual contact has been suggested as possibly responsible for the second peak of HBV infection in the Kingdom.1 Interestingly, our results suggest that marital status, being the major means of heterosexual contact in Saudi Arabia, did not seem to correlate statistically with the risk of acquiring HBV infection or developing HBsAg carrier status. Thus, although premarital screening may be optional at the individual level, it may not be cost-effective to adopt it as a national health policy. Alternatively, however, a precollege screening program may be more beneficial to implement for 12-15 years to come until the first generation who have been vaccinated during their neonatal age, reach the pre-college age.

The analysis of the ALT results suggests that HBV infection and increased ALT are not necessarily predictors of each other. Interestingly however, at a level of ALT higher than 70 IU/L, a statistically significant correlation with HBV infection is present. Noticeably, the majority of subjects with increased ALT were negative for HBsAg and anti-HBc. Since the study has been conducted in an industrial community, it will be interesting to look for possible chemically or environmentally induced toxic liver disease in Yanbu Industrial city.

In conclusion, this study allows new insights into the epidemiology of HBV and liver disease in Saudi Arabia and prompts further studies for the future.