INTRODUCTION

    Hepatitis virus infections are an increasing problem,

with millions people all over the world being infected. It is

accepted as a significant public health problem with several

life altering complications. Five viruses are usually associated

with hepatitis in humans: hepatitis A virus, hepatitis B virus,

hepatitis C virus, hepatitis D virus and hepatitis E virus [1].

In addition to these viruses as etiological agents of hepatitis,

Sehgal and Sharma said that there remained a number of

patients with hepatitis in whom no virus could be identified

and it was therefore postulated that there may be other agents

which may be causing hepatitis [1].

    Recently, new viruses have been identified for their

association with hepatitis. Hepatitis SEN is a single-chain

DNA virus which represents a newly discovered virus.

Epidemiological data indicate that the virus can be transmitted

via blood/blood products. However, there are limited reports

on the prevalence of SEN infection among the blood/blood

products. The purpose of this study is to summarize the

prevalence of SEN infection, defined as SEN DNA positive,

among the voluntary blood donors in the previous reports.

MATERIALS AND METHODS

    This study was designed as a descriptive retrospective

study. A literature review on the papers concerning SEN

infection among the voluntary blood donors was performed.

The author performed the literature review to find the report of

prevalence of SEN infection, given definition as positive for

SEN DNA or viremia, from database of the published works

cited in the Index Medicus and Science Citation Index. The

literature review was focused till October 2004. The reports

without complete data, those not focusing on the voluntary

blood donor (such as paid and commercial donors) and those

lack for English text, were excluded.

    According to the literature review, 4 available reports [2

- 5] were recruited for further study. The summarization of

the prevalence of SEN infection from all included reports

was performed. Descriptive statistics, including range and

percentage, were used in summative analysis. Chi Square test

was used to assess the association between race of the subjects

and prevalence of infection. All the statistical analyses in this

study were made using SPSS 7.0 for Windows Program.

RESULTS

    Due to this study, there have been at least 4 literatures

reporting [2 – 5] (Table 1). Of 511 documented voluntary

donors, there were 88 cases with SEN DNA positivity (Table

1). The summative percentage for SEN DNA positivity was

17.2 %. There is no significant association between the race

and the prevalence of SEN DNA positivity (p > 0.05).

DISCUSSION

    SEN is a newly documented hepatitis virus [1]. Infection

with this virus is common and frequently persists in humans

[1]. Similar to many hepatitis viruses, transfusion of viremic

blood/blood product can be the route of this viral infection. At

present, SEN hepatitis virus is identified as a single-stranded

circular, non-enveloped DNA virus of approximately 3600

to approximately 3800 nucleotides with at least three open

reading frames (ORFs) [6]. SEN infection is widely studied

for the clinical association with acute or chronic hepatitis [6].

Further researches for the possible diseases caused by this

viral infection are continuously performed.

    Sagir et al said that although parenteral transmission of

SEN was very likely, other routes of transmission could not be

excluded. Mother to infant transmission has been demonstrated

[7]. They noted that theå effect of SEN infection on chronic

liver diseases had been studied and the influence of SEN

infection on the response to HCV therapy was investigated

with contradictory results [7]. Screening for SEN DNA in

the donated blood can be a good tool to detect viremia and

prevention for SEN transmission by blood transfusion [8 - 9].

    Here, the author reports the summative prevalence of SEN

DNA positivity from screening of voluntary blood donors.

The prevalence of SEN viremia in this study is about 18 %.

However, there is no significant association between race

and the positivity. According to this study, the SEN infection

seems to highly distribute in many countries, implying the

global importance of this hepatitis virus infection. Screening

for SEN DNA might be an important screening in blood bank