Prevalence of cytomegalovirus in paid and unpaid blood donor population in Tirana.
Cytomegalovirus (CMV) is one of the most transmitted infectious agents through blood transfusion. There were no reports on the prevalence of CMV in our donor population.
The aim of the study was to determine the epidemiology of CMV infection in blood donors and to compare the prevalence of CMV antibodies in paid and unpaid blood donors.
Materials and methods
The blood donor population was divided in paid blood donors (PBD, 1308) and unpaid blood donors (UBD, 415). Total CMV antibody assay results were analyzed and correlated with donor age, sex and socio-economic status in the whole donor population and in both groups.
The CMV seroprevalence in blood donor population was 83%. The PBD showed significantly higher prevalence of total antibodies anti-CMV when compared with UBD, 92.9% vs. 51.8%.
Significant association of CMV seroprevalence with social class was noted, 88.3% "in low social class" towards 54.9%. The relationship between donor age and CMV status showed an increase in the percentage of seropositivity with age (65% in ages under 30 years old, 91.5% in ages more than 50 years old). The prevalence of the specific antibodies anti-CMV IgM was 5.5%.
This study showed that the population of blood donors is a population with high prevalence of CMV infection especially in PBD. Studies in patient populations are needed. Leucoreduction only might not be sufficient for all at risk patient populations.
Keywords: Cytomegalovirus, prevalence, blood donation, socioeconomic factors, population characteristics
Epidemiology (Health aspects)
Immunoglobulins (Social aspects)
Immunoglobulins (Health aspects)
Blood banks (Social aspects)
Blood banks (Health aspects)
Blood banks (Analysis)
Medical research (Social aspects)
Medical research (Health aspects)
Medical research (Analysis)
Medicine, Experimental (Social aspects)
Medicine, Experimental (Health aspects)
Medicine, Experimental (Analysis)
Infection (Social aspects)
Infection (Health aspects)
Prevalence studies (Epidemiology) (Social aspects)
Prevalence studies (Epidemiology) (Health aspects)
Prevalence studies (Epidemiology) (Analysis)
|Publication:||Name: International Journal of Health Science Publisher: Renaissance Medical Publishing Audience: Academic Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2009 Renaissance Medical Publishing ISSN: 1791-4299|
|Issue:||Date: Oct-Dec, 2009 Source Volume: 2 Source Issue: 4|
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Selection of cytomegalovirus (CMV)-seronegative blood is a recognized way of providing blood with a greatly reduced risk of CMV transmission. (1) This association has focused attention on the epidemiology of CMV infection in blood donor population.
Human CMV is a herpes virus which is present as a latent infection in a majority of population in many countries. It causes a potentially dangerous infection that may become fatal to immunocompromised patients. (2,3) Seropositivity differs in different parts of the world 40-100% (4,5,6) and is therefore very important to establish local epidemiology in order to assess the risk of CMV transmission through blood transfusion.
Primary CMV infection of CMV-seronegative patients can occur through transfusion of blood products from CMV-seropositive donors. In seropositive donors, latent CMV is found in peripheral blood monocytes (7), to a much lesser extent CMV exists as free virus in the plasma of window period donors. (8)
The prevalence of CMV in general population and among blood donors in Albania has not yet been documented. This work has been performed in order to determine the rate of seropositivity among blood donors in Albania, to compare the seropositivity among two groups of blood donors paid and unpaid and to use this data in developing proper strategies for reducing CMV infections through blood transfusion, especially in immunocompromised patients.
MATERIALS AND METHODS
National Blood Transfusion Centre in Tirana collects blood from two different groups of blood donors:
1--Paid blood donors
2--Unpaid blood donors which from their side are divided in:
a. Voluntary non remunerated blood donors
b. Family replacement donors
The population studied is the population of blood donors in Tirana during the years 2007-2008, divided as it is mentioned above in two groups of paid (1308) and unpaid (415) blood donors. Prevalence of anti-CMV is determined in total and divided according to age, sex, and social class in the blood donor population in general and also in each of the groups of donors. For determining the social class only the occupation of the donors was taken into account, and the donors were divided in workers/jobless (low/middle class) and intellectuals (high social class).
Serum from each donor was tested for total CMV antibody using the Abbott AxSYM System in which a micro particle enzyme immunoassay (MEIA) was utilized. Those resulted positive were further tested for anti-CMV IgM by the same method. Calibration procedures were performed and validated using positive and negative controls provided. Micro plates coated with human CMV strain (AD169) were incubated with test sera. After washing in Tris buffer, antihuman IgG conjugated with alkaline phosphatase was added, washed and reaction was probed with methylumbelliferyl phosphate. Positive and negative controls were provided and utilized for system calibration. Assay results less than 15 AU/ml were considered negative for IgG antibodies to CMV. Samples with results > 15 AU/ml were considered positive indicating the presence of past or current infection. The tests were performed and results were calculated according to the manufacturer's instructions. All samples were immediately separated on receipt and frozen at 30[degrees]C until tested. Thawing and freezing was kept to a minimum.
The test [chi square] was used for studying the association between the prevalence of CMV and gender, age-group, social-class. When the p value was <0.05, this was considered as a statistically significant result. All the statistical analysis of the data was done with SPSS (Statistical Package for Social Sciences) version 10.0 (Chicago, Inc).
The overall prevalence of CMV in our population of blood donors was 83%. Prevalence of CMV in paid blood donors resulted significantly higher in comparison to the prevalence of CMV in unpaid blood donors (92.9% vs 51.8%, Tables I-III and Figures I,II). We also studied the relationship of the prevalence of CMV with the donor sex, age- group and social-class. The evaluation of the relationship between donor sex and CMV status showed no significant difference (83.5% in females vs 82.5% in males, Table IV).
For the statistical analysis, the donors were grouped in age-groups in intervals of 5 years except from 18-30 which were grouped as <30 years old, and 50-65 who were grouped as >50 years old, because of the small number of donors in comparison to other groups, as shown in Table V. The evaluation of CMV prevalence and age-group showed an increase of seropositivity with the age in the general donor population (65%-91.5%). In the population of paid blood donors a high prevalence of CMV is noted since in early ages <30 years old (94.1%) that increased with the age up to 96% in the age group >50.
The relationship between the social class and the CMV seropositivity is shown in Table VI. In the social class of workers/ jobless there was a significantly higher prevalence of seropositivity in comparison to the class of intellectuals (88.3% vs. 54.9%). The incidence of anti-CMV IgM was 5.5% (79 in 1430, Figure III).
The prevalence of CMV in our population of blood donors in general resulted in 83%. The prevalence in the unpaid blood donors was 51.8% whereas in the paid blood donor population was 92.9% (Tables I-III and Figures I,II). The results indicate prevalence statistically significant higher in paid blood donors than in unpaid blood donors. A higher prevalence of infectious agents in paid blood donors is reported from different studies. (9,10) If we refer also to the fact that 99,6% of paid blood donors in our study belong to the "low/middle social class", then a relationship also with this fact is found. This fact is confirmed also from other publications, where the prevalence of CMV is higher in the lower social class. (1,11)
The relationship between the social class and the prevalence of CMV in our study is shown in Table VI. For determining the social class in this study we were based only in the occupation, and it was noted a statistically significant higher prevalence of CMV in the "Low-middle social class" than in the "high social class". As mentioned above according to the occupation our donors were divided in intellectuals "high social class" and in worker/jobless "low-middle social class". This division of social class based on the employment alone is referred also from other publications (1) but is very important to mention that employment is not the only parameter taken into account when you divide the social class, but also the social-economic and cultural components are very important.
No association was found between CMV seropositivity and donor sex Table IV. This is similar to the findings of other authors. (12) CMV seropositivity increases with age. This finding is in agreement also with other authors. (1,13) In our study, the seropositivity increases with the age of the donors (from 65% in the ages under 30 years old, to 91.5% in the ages over 50 years old, Table V). This local information is very important because if we select younger donors we can have more donations CMV neg. So if seroprevalence of CMV in the whole donor population was 83%, in the ages <30 years old was 65% and even more if we select the unpaid blood donors <30 years old the prevalence decreases to 27.5%. More efforts should be directed towards recruitment of unpaid blood donors, where the prevalence of CMV but also other infections is lower than in paid blood donors. (9,10) Prevalence of specific anti-CMV antibodies IgM resulted in 5,5% (79 from 1430, Figure III). In the literature, we find prevalence of IgM specific that varies 1-13%.14,15 No association was found between levels of IgM and total CMV antibody.
According to this data, the prevalence of CMV is very high in our blood donor population. The impact of this high prevalence of CMV in the "high risk" patient population is still not studied and reported, but it is sure that with this high prevalence of CMV in blood donor population, an urgent intervention is needed for preventing transfusion-transmitted CMV (TT-CMV) for patient at high risk for this disease. Since latent CMV is found in peripheral blood monocytes (7), there are a lot of studies that refer a decrease in the transmission of CMV by leukoreduction of blood components. (16, 17) Therefore, the interventions could be "universal leukoreduction of blood components" and of course "screening of all blood units for CMV" or both. The coming year we are going to begin with universal prestorage leukoreduction, because this has come as a necessity. First of all, for preventing TT- CMV, based on the data of this study, but also for preventing febrile non-hemolytic transfusion reactions in multi-transfused patient populations (major beta thalassemia patients). The question is if leukoreduction only is enough in preventing TT-CMV for patients with high risk. From the literature, there are a lot of studies, which show that TT-CMV has occurred after leukoreduction. (18,19,20) The residual risk of leukoreduction only, versus CMV seronegative units only, has been 2.73% vs. 1.45% respectively (21) and there are no studies until now that compare seronegative/leukoreduced versus leukoreduced only blood components. Therefore, in many countries e.g. Ireland and the UK where universal leucoreduction has been introduced, patients who require CMV 'safe' products are receiving both CMV seronegative and leucoreduced blood components. This is shown also from the meta-analysis conducted from Vamvakas EC (21) who concludes that seronegative/ leukoreduced give the level of protection needed and should be used in preference to CMV-unscreened/leukoreduced components for patients of SCT (stem cell transplantation) setting, seronegative pregnant women and intrauterine fetal transfusions who are the patients at the highest risk for TT-CMV disease.
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Since about 83% of blood donors in our country are seropositive for CMV, it would be very useful to screen all blood donors for CMV, to identify the CMV-seronegative blood donors and maintain an inventory of them for use as donors for immuno-suppressed individuals that belong to the highest risk groups (SCT patients, seronegative pregnant women and intrauterine fetal transfusions), whereas for other patient populations (preterm infants, cancer patients, HIV infected patients etc) we might go on only with leukoreduction, because the use of seronegative/leukoreduced blood components in all patient populations at risk for TT-CMV will imply an important change in blood banking practice in Tirana with significant financial implications.
The general observation of this study is that our donor population has a high prevalence of CMV antibodies, in this situation developing and maintaining an inventory of CMV-seronegative blood donors might be the right solution for selected at the highest risk patient population. Studies should be done also in patient populations in order to assess the impact of this high prevalence of CMV in blood donors.
More efforts should be directed towards recruitment of unpaid blood donors as a safer population of donors not only for CMV infection but also for other infections. Relationship between CMV seroprevalence and donor sex, age and social class resulted in our study as reported before in the literature.
Conflict of interest: None declared.
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Irena Seferi , Pal Xhumari , Genc Burazeri 
 National Blood transfusion Centre of Tirana, Albania
 Department of Haematology, University Hospital of Tirana, Albania
 Department of Public Health, University Hospital of Tirana, Albania
Corresponding author: Irena Seferi, NBTC, Tirana, Rruga Lord Bajron, Lapraka, Albania Telephone number: +355 4 2389901, +355682000124 Email: email@example.com.
Table I. CMV prevalence in the general donor population (paid and unpaid donors) Number Percentage No 293 17.0 Yes 1430 83.0 Total 1723 100.0 Table II. CMV prevalence in unpaid donors Number Percentage No 200 48.2 Yes 215 51.8 Total 415 100.0 Table III. CMV prevalence in paid blood donors Number Percentage No 93 7.1 Yes 1215 92.9 Total 1308 100.0 Table IV. CMV prevalence in general population (paid andu npaidd onors) according to donor sex Donor sex Total Femal Male CMV No 136 157 293 16.5% 17.5% 17.0% Yes 689 741 1430 83.5% 82.5% 83.0% Total 825 898 1723 100.0% 100.0% 100.0% Table V. CMV prevalence in the general population (paid and unpaid) according to age-group Age-group <30 31-35 36-40 41-45 46-50 >50 CMV No 105 47 52 39 31 19 35.0% 16.4% 15.3% 12.3% 12.4% 8.5% Yes 195 240 288 278 220 206 65.0% 83.6% 84.7% 87.7% 87.6% 91.5% Total 300 287 340 317 251 225 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% Table VI. CMV prevalence in general population of donors (paid and unpaid) according to social class Social class Low/Middle High CMV No 170 123 11.7% 45.1% Yes 1280 150 88.3% 54.9% Total 1450 273 100.0% 100.0% Figure III. Prevalence of IgM specific IgM specific Yes 79 No 1351 Note: Table made from bar graph.
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