Prevalence of cytomegalovirus antibodies in blood donors at the national blood transfusion centre, Nairobi - Kenya
Background Cytomegalovirus (CMV) is known to be associated with significant morbidity and mortality following homologous blood transfusion in neonates and other immune compromised persons. Documentation of the status of antibodies to cytomegalovirus in the blood donor pool in our setting is vital to the understanding of the potential likelihood of transmission through donor blood and for determining the best transfusion practices to prevent transfusion-acquired CMV infection. There is little information available with regards to the level of Cytomegalovirus antibodies in donor blood at the National Blood Transfusion Centre in Nairobi. Objective To determine the prevalence of CMV infection among blood donors at the National Blood Transfusion Centre (NBTC). Design and Setting A cross sectional study conducted at the National Blood Transfusion Centre, Nairobi and the University of Nairobi immunology laboratory. Methods Four hundred eligible blood donors, as defined by the NBTS criteria, were studied. Demographic data (age, gender, marital status, level of formal education, geographical area of residence and monthly income) was obtained by direct interviews. Documentation of laboratory results for Human Immunodeficiency Virus (HIV), syphilis, hepatitis B and hepatitis C was done from donor registers at the NBTC. Enzyme-linked immunosorbent assay (ELISA) tests for anti-CMV IgG and IgM antibodies were carried out at the UON immunology laboratory. 1 Data handling The data collected and that generated from the laboratories were entered in pre-designed study questionnaires. This data was then entered into a computer data base from which spreadsheets were generated and transferred to the SPSS (version 15) statistical software for analysis. Summary of the statistics was determined during the analysis and presented as proportions and percentages in the form of tables and graphs. Results A total of 400 blood donors were recruited into the study out of whom 57.9% were male and 42.1% were female. The age group pattern showed that: 42.5% were in the 16 to 20 years age bracket, 24.3% in the 21-25, 14.4% in the 26-30 and 17.2% were above 30 years of age. The unmarried participants constituted 78.5% whereas 20.5% were married and 0.8% were divorced. The educational level profile was as follows; only primary school education 5.4%, secondary school 54.8%, college 33.9% and university 5.9%. Their monthly incomes were; 31.1% less than Kshs 5,000, 66.1% between 5,000 and 50,000 and 2.9% between 50,000 and 100,000. Of all the participants 60.5%, were sexually active while 39.5% recorded that they were not. There were 97.0% and 3% of the studied participants who tested positive and negative respectively for anti-CMV IgG antibodies. Those who tested positive for anti-CMV IgM were 3.5% while 96.5% tested negative. All the participants who tested positive for anti- CMV IgM antibodies also tested positive for anti-CMV IgG antibodies. Female blood donors showed a higher prevalence of anti-CMV IgG than male donors (p=0.016). There was however no statistically significant difference in the prevalence of IgM between the genders (p=0.955). The study did not show any statistically significant difference in sero- prevalence (of both IgG and IgM) with age, marital status, education level, income or occupation. Those who tested positive for HIV were 1.3% while 98.7% tested negative. There were 0.3% participants who were positive for syphilis and 99.7% who were negative. Hepatitis B positive participants were 2.3% and 97.7% were negative. Those positive for Hepatitis C were 1.0% while 99.0% were negative. 2 Conclusions This study shows that the prevalence of anti-CMV antibodies in blood donors at the NBTC was 97% and 3.5% for IgG and IgM respectively. Female blood donors showed a higher prevalence of anti-CMV IgG compared to the male donors. The study does not demonstrate any significant influence of age, marital status, education or even the sexual status on the prevalence of anti-CMV antibodies. Infection with other transfusion transmissible infections does not show any significant relationship with infection with CMV. Recommendations It is important to screen donor blood for anti-CMV IgM especially that which is intended for transfusion to patients at the risk of severe morbidity from CMV disease. Further studies will be necessary to determine the reasons for the difference in the sero- prevalence of IgG between female and male donors as well as to determine the age of seroconversion of (and therefore the earliest exposure to) CMV. It is also recommended that the high risk groups who have been transfused be evaluated to determine if they may have acquired transfusion-transmitted CMV.