Academic journal article Central European Journal of Public Health

Cytomegalovirus Immunoglobulin G Avidity Index among Blood Donors in Alexandria, Egypt

Academic journal article Central European Journal of Public Health

Cytomegalovirus Immunoglobulin G Avidity Index among Blood Donors in Alexandria, Egypt

Article excerpt

INTRODUCTION

Transfusion transmitted diseases (TTD) are a major challenge to transfusion services all over the world (1). Transfusion of unscreened cellular components leads to a TTD incidence of approximately 30% in seronegative recipients (2). The presence of viruses in blood cells or plasma of asymptomatic donors is the major risk factor for transmitting infectious agents through blood transfusion. The main viruses associated with transfusion related infections are hepatitis viruses, retroviruses and cytomegalovirus (CMV) (3).

CMV is the largest member of the herpesviridae family (4). It has the ability to remain latent within the T-cells, endothelial cells and monocyte-derived macrophages and may be reactivated from latently infected cells after blood transfusion (5, 6). CMV seems to have a large impact on immune parameters in later life and may contribute to increased morbidity and eventual mortality (7).

Several studies have reported that CMV immunoglobulin G (CMV IgG) is transmitted by blood transfusion from healthy seropositive donors to susceptible recipients (8-10). Vulnerable groups to serious illness caused by this virus are immunocompromised hosts, neonates and pregnant women (5, 6). Exclusion of seropositive blood units and leucodepletion are the two main strategies to minimize CMV transmission to high risk recipients (11).

CMV has a worldwide distribution. It is more widespread in developing countries and in communities with lower socioeconomic status. Between 50-80% of adults in developed countries and up to 100% in developing countries are infected with human CMV. It represents the most significant viral cause of birth defects in industrialized countries (12). Several studies have demonstrated a strong link between primary CMV infection of the mother and in utero CMV transmission. The risk of congenital infection is approximately 40% in babies born to mothers who acquire a primary (initial) CMV infection after conception; in contrast, the risk is only about 1% in infants born to mothers who have evidence of CMV infection (i.e. circulating CMV antibodies) before conception. The established link between primary CMV infection during pregnancy and congenital infection makes identification of primary CMV infection an important goal in maternal and neonatal health care (13). Applying this concept to donated blood - safe blood for transfusion would be that without evidence of primary CMV infection (11).

As it has the ability to remain latent, CMV infection in im- munocompetent persons is subclinical and the diagnosis mainly relies on serology (12).

CMV specific IgM is an extremely sensitive marker of primary CMV infection. Unfortunately, CMV IgM detection is not specific for primary infection due to its production following reinfection or reactivation in some individuals. Likewise, demonstration of increasing levels of CMV IgG overtime is an impractical approach since most patients already show high IgG levels in the first tested serum sample. Therefore, when IgM is detected, it is advisable to use a complementary test to establish the date of CMV infection. The most useful test is the measurement of the IgG avidity index which has been shown to help in distinguishing primary from past or recurrent infection (14).

As CMV screening is not included in routine screening tests done for donated blood in blood banks in Egypt, the detection of CMV Ig G avidity needed to be tested for being a useful tool to diagnose recent infection among blood donors. This work aimed to study CMV Ig G avidity index among blood donors.

MATERIALS AND METHODS

This cross sectional study was carried out through a three month period from July to September 2010. It involved 88 volunteer blood donors who attended the Alexandria Regional Blood Transfusion Centre (ARBTC), one of the Ministry of Health and Population Centres.

Non remunerated volunteer blood donors were selected according to the standard operating procedures adopted by the Donor Care Department (DCD) in ARBTC (15, 16). …

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