Summary
Introduction: Epstein-Barr virus (EBV), also known as human herpesvirus 4, is the causative agent of infectious mononucleosis. Infection with EBV is associated with multiple malignancies. The aim of this study was to determine the seroprevalence and risk factors for seropositivity.
Materials and Methods: This study was conducted in Haydarpaşa Numune Training and Research Hospital in İstanbul between August 2012 and October 2012. Epstein-Barr virus viral capsid antigen IgG antibody was measured using ELISA in 500 cases. Age, gender, occupation, education level, family income, the area and type of residence, and chronic illness of the participants were also evaluated. Differences between risk groups were statistically analyzed.
Results: The mean age of the 500 study participants was 47.7±19.1 (15-87) years and 289 (57.8%) were male. Mean EBV seropositivity was 96.4%, and 91% of the cases became seropositive for EBV by 15 years of age. No significant associations with age, gender, occupation, education level, family income, area and type of residence, and chronic illness were detected.
Conclusion: Epstein-Barr virus seropositivity rates were very high and about 91% of the cases become seropositive for EBV by 15 years of age. There was no significant relationship between risk factors and seroprevalence of EBV.
Introduction
The serologic profile of EBV infection is determined using specific antibodies against the major antigens of the virus including EBV nuclear antigen, early antigen, and viral capsid antigen (VCA)[2]. Viral capsid antigen IgM is found in the serum for 4-8 weeks during the active phase of the disease. In contrast, EBV VCA IgG appears early in acute infection and remains positive for the lifetime of the patient. Therefore EBV VCA IgG is commonly used in epidemiologic studies[3]. Epstein-Barr virus seropositivity rates in adults in Turkey have been reported as 80-99.4%[3, 4].
Due to the oncogenic potential of EBV and its known role as an etiologic factor for many idiopathic diseases, determining EBV seropositivity is important for identifying individuals at risk[5]. The present study was conducted with individuals over the age of 15 living in İstanbul, where receives immigrants from many regions of Turkey. The aim was to determine EBV seroprevalence and identify any significant differences in seroprevalence based on age, sex, occupation, education level, economic status, chronic diseases, and place and type of residence.
Methods
A venous blood sample of about 5 cc was obtained from the participants and the serum samples were preserved at -20 ˚C until analysis. Micro-ELISA was used to measure EBV VCA IgG antibody levels (NovoTec NovaLisa EBV VCA IgG ELISA (Dietzenbach, Germany) as per the manufacturer"s instructions. The formula n=t²pq/d² was used to calculate the sample size required to determine the EBV VCA IgG seroprevalence in the adult Turkish population.
Statistical Analyses
Statistical analyses were done using the "Number Cruncher Statistical System" 2007 Statistical Software package (Utah, USA). Data were analysed using descriptive statistics (mean, standard deviation) and categorical data were compared using Chi-square and Fisher's exact test. The results were evaluated at a significance level of p<0.05.
Results
Analysis of seropositivity rates in terms of participants" occupation, education level, and income levels revealed no statistically significant differences (p>0.05 for all) (Tables 4, 5, 6). There were no statistical differences in seropositivity according to the participants" place of and type of residence (p>0.05) (Table 7). The presence of a chronic disease was also not significantly associated with EBV VCA IgG positivity (p>0.05) (Table 8).
Table 6: Epstein-Barr virus viral capsid antigen IgG positivity distribution by monthly income level
Discussion
It is known that having an EBV infection at an early age has harmful effects. Burkitt lymphoma is more common among infants who have primary EBV infection at very early ages and the accompanying high EBV viremia[8]. Many studies have shown that EBV seroprevalence increases with age[7, 9-11]. In our study, presence of EBV IgG antibodies was analysed in individuals aged 15 years and over. The EBV IgG positivity rate was 90.77% in the 15-25 years group and 97.78% in participants over 75 years old, with no statistically significant differences between age groups. This lack of significant age-related differences in seropositivity may be due to the participants having encountered a large number of viruses before the age of 15.
We also analyzed sex differences in EBV seropositivity and found that seropositivity rates were higher in males than in females. However, the difference was not statistically significant. In a study conducted with students of Edinburg University, Higgins et al.[12] determined seropositivity rates of 68.1% in males and 78.5% in females, which was a statistically significantly difference. In another study of children between 6-19 years of age, EBV seroprevalence was found to be higher in girls than in boys (68.9%, 64.2%)[13]. A study by Özkan et al.[3] demonstrated that women had similar rates to men.
In the present study, we investigated the relationship between EBV seropositivity and education level as well. The participants were classified as illiterate, literate without formal education, primary school graduate, secondary school graduate, high school graduate, and university graduate/postgraduate. No statistically significant association was found between educational level and seroprevalence. This result is consistent with that reported by Özkan et al.[3]. In contrast, Balfour et al.[9] analyzed the relationship between family education level and seropositivity and found that seropositivity was 72% for those who did not attend high school, 63% for high school graduates, and 56% for those with education beyond high school. Another study showed that EBV seropositivity in individuals with education below high school, at the high school level, and beyond high school was 83.5%, 69.5%, and 59%, respectively[13]. As suggested by these studies, higher education level has been linked to better hygiene habits and consequently a lower risk of virus transmission. High levels of transmission in childhood indicated the importance of family education.
Being infected with EBV is known to be affected by socioeconomic status[3]. A study analyzing the correlation between income level and EBV seropositivity reported rates of 81% in the lowincome group, 75% in the mid-level income group, and 53.9% in the high-income group[13]. In a seroprevalence study including 283 individuals in Brazil, it was reported that EBV seropositivity increases with decreasing socioeconomic level of the families[14]. However, the findings of our study indicate that EBV seropositivity does not change significantly according to income level.
A limitation of our research is that our analysis only included adults, and did not include children. Therefore, we were unable to identify differences in seroprevalence among children, among whom EBV exposure is the highest and general manifests with subclinic infection, and we could not determine the risk factors that affect seropositivity in this age group.
Conclusion
Ethics
Ethics Committee Approval: Ethics Committee approval was obtained from the Haydarpaşa Numune Training and Research Hospital Ethical Council (Decision number: HNEAH. KA.EK-2012/50).
Informed Consent: Consent form was filled out by all participants.
Peer-review: Externally and internally peer-reviewed.
Authorship Contributions
Surgical and Medical Practices: J.A., Concept: J.A., S.E., D.Ö.E., S.Ö., S.Ş., A.İ, Z.A.D., Design: J.A., S.E., D.Ö.E., Data Collection or Processing: S.Ö., S.Ş., A.İ, Z.A.D., Analysis or Interpretation: J.A., D.Ö.E., Literature Search: J.A., D.Ö.E., Writing: J.A., S.E., D.Ö.E., S.Ö., S.Ş., A.İ, Z.A.D.
Conflict of Interest: No conflict of interest was declared by the authors.
Financial Disclosure: The authors declared that this study received no financial support.
