Mercury and measles virus antibodies in US children, NHANES 2003-2004

Environmental toxins, pathogens and host susceptibility are cofactors that may interact to contribute to disease. In vitro mercury exposure inhibits antiviral cytokines in human cells; however, little is known about the relationship between mercury and viruses in children. Children are particularly susceptible to mercury neurotoxicity; lower vitamin B-12 and folate levels and higher homocysteine levels may represent susceptibility cofactors. This study aimed to evaluate associations between total blood mercury (Hg) and measles antibodies, and the influence of susceptibility cofactors. Cross-sectional data on these analytes, including methylmalonic acid (MMA, indicator of B-12 deficiency), were obtained from the 2003-2004 National Health and Nutrition Examination Survey for children aged 6-11 years with measles seropositivity (n=692). We used linear regression to evaluate relationships between measles antibodies and continuous Hg and Hg quartiles (Q, µg/L) {Q1: Hg<=0.20; Q2: 0.20-0.40; Q3: 0.40-0.80; Q4: > 0.80}, stratified by sex, MMA>=, folate <, and homocysteine>= sample medians, adjusted for demographic, nutritional and environmental cofactors. Continuous Hg was inversely associated with measles antibodies in non-stratified analysis, yet positively associated among the subset of boys with higher MMA and lower folate (n=98); among subset boys with higher homocysteine levels (n=61), correlations were positive across all Hg quartiles relative to Q1: Q2: ß=6.25 (2.45, 10.04); Q3: ß=8.69 (6.39, 11.00); Q4: ß=5.62 (3.09, 8.15) (ptrend=0.037). These results suggest that mercury may be associated with levels of serum measles antibodies. This is important because additional research is needed to clarify this relationship.