Cytomegalovirus seroprevalence, recurrence, and antibody levels: Associations with cadmium and lead exposures in the general United States population

Background: The ubiquitous metals cadmium and lead are immunotoxic, but little is known about their relations to cytomegalovirus (CMV), a widespread herpesvirus. Although CMV infections are mostly asymptomatic, congenital infections are a leading cause of birth defects. In otherwise healthy individuals, there is also some evidence linking subclinical reactivations to accelerated age-related declines in immune function and chronic disease.

Methods: Our objective was to evaluate associations of blood cadmium and lead biomarkers with CMV infection in a representative sample of the United States population. In seropositive individuals, we also examined associations with CMV-specific immunoglobulin G (IgG) antibody levels and suspected CMV recurrences. Using cross-sectional data from the 1999-2004 National Health and Nutrition Examination Surveys, we fit multivariable survey-weighted regression models accounting for potential confounding by sociodemographic and lifestyle factors and stratifying by age group to allow for heterogeneity. CMV recurrences were defined according to (1) the presence of either CMV-specific immunoglobulin M in sera or CMV viral DNA in urine, and (2) high CMV-specific IgG avidity.

Results: We observed null associations for blood cadmium. Increasing blood lead quartiles were related to CMV seropositivity and higher CMV IgG levels (both P _trend < 0.01), but not CMV recurrence, only among individuals who were 20-29 years of age.

Conclusion: Blood cadmium levels do not appear to be related to immunological markers of CMV infections. The possibility that lead exposures increase the risk of CMV infection and impair immune control of the virus in young adults was suggested. Prospective studies are needed to confirm.