Cytomegalovirus Infection in Ireland

Cytomegalovirus (CMV) infections occur worldwide and primary infection usually occurs in early childhood and is often asymptomatic whereas primary infection in adults may result in symptomatic illness. CMV establishes a chronic latent infection with intermittent periods of reactivation. Primary infection or reactivation associate with increased mortality and morbidity in those who are immunocompromised. Transplacental transmission may result in significant birth defects or long-term sensorineural hearing loss. We performed a study to determine the CMV seroprevalence and the association between HLA Class I alleles and frequency of CMV infection in Ireland. The presence of CMV IgG, a marker of previous CMV infection, was determined for a cohort of 1849 HLA typed solid organ transplant donors between 1990 and 2013. The presence of CMV IgG was correlated with HLA type. The CMV seroprevalence in solid organ transplant donors was 33.4% (range 22–48% per annum) over the time period 1990 to 2013. Multivariate logistic regression analysis showed that both age and HLA alleles were associated with CMV seropositivity. A significant and positive relationship between age and CMV seropositivity was observed (OR1⁄4 1.013, P< 0.001, CI [1.007, 1.019]). Chi-square analysis revealed that the female gender was independently associated with CMV seropositivity (P< 0.01). Seroprevalence in women of reproductive age (20–39 years) was significantly higher than men of the same age (37% vs 26%, P< 0.01). The frequencies of HLA-A1, HLA-A2, and HLA-A3 in our cohort were 40.8%, 48.8%, and 25.9%, respectively. Logistic regression analysis showed that the presence of HLA-A1 but not HLA-A2 or HLA-A3 was independently associated with CMV seronegativity (P< 0.01). Interestingly, individuals who cohD, FRCPath, Ma D, FRCPath, MD, FRCPath respectively. The presence of the most common inherited haplotype in the Irish population, HLA-A1, B8 was significantly associated with CMV seronegativity (OR1⁄4 1.278, P< 0.001, CI [1.049, 1.556]). CMV seroprevalence is lower in Ireland compared with other countries. The high frequency of HLA-A1 in the Irish population may, in part, have a role in the reduced susceptibility to CMV infection. (Medicine 95(6):e2735) Abbreviations: CI = confidence interval, CMV = cytomegalovirus, HLA = human leucocyte antigen, IFN = interferon, Ig = immunoglobulin, OR = odds ratios. INTRODUCTION C ytomegalovirus (CMV) is a member of the herpes virus family. It is a 235-kb double-stranded linear DNA virus and is transmitted via saliva, urine, and most other bodily fluids of infected individuals. In addition, CMV can be transmitted through infected organs and blood products. This ease of transmission results in particularly high seroprevalence in certain parts of the world. However, seroprevalence differs greatly from country to country ranging from 50% up to 90% depending on many factors including ethnicity and socio-economic status. Primary CMV infection gives rise to lifelong latency and reactivation can occur. Congenital cytomegalovirus infection, which has an occurrence of between 0.2% and 2.5% worldwide, may result from primary infection, reactivation of maternal CMV infection, or reinfection with another CMV strain. Primary infection is associated with increased morbidity and mortality for the fetus. Publications describing CMV seroprevalence have generally restricted the population cohorts studied to pregnant women. A meta-analysis among women of reproductive age showed that globally CMV seroprevalences ranged from 40% to 100%. 1 The highest seroprevalence rates were observed in Africa, Asia, and South America and the lowest rates were observed in Western Europe and North America. A study examining pregnant women in Ireland in 2002 found that CMV seroprevalence in Irish women at 30.4% was significantly lower than that in non-Irish pregnant women (89.7%) who were mostly from Sub-Saharan Africa, Eastern Europe, and Asia. CMV infection in immunocompetent individuals is usually asymptomatic, although symptomatic infection is more common as age at primary infection increases. CMV IgG seropositivity is considered the best laboratory measure of past CMV infection. However, cell-mediated immunity is more important than humoral immunity in controlling CMV infection. Cellular immune responses measured as the in vitro production of IFN-g ytes in response to CMV peptides has s a biomarker associated with the risk of ease post-transplant. As these cellular www.md-journal.com | 1 (OR1⁄4 1.013, P< .001, CI[1.007, 1.019]). Chi-square analysis revealed that female gender was independently associated with CMV seropositivity (P< 0.01). Overall women showed a Medicine Volume 95, Number 6, February 2016 immune responses are restricted by HLA Class I alleles for peptide recognition, in addition to determining the CMV seroprevalence rate in Ireland, the association of CMV seropositivity with HLA Class I alleles was also examined. MATERIALS AND METHODS