Humoral immunity following chickenpox is influenced by geography and ethnicity.

OBJECTIVES: To investigate the contribution of ethnicity and geographical location to varicella-zoster virus (VZV) serostatus and antibody concentrations. METHODS: The presence and concentrations of antibodies to VZV were measured in 639 Bangladeshi women born in Bangladesh (BBB), 94 Bangladeshi women born in the UK (BUK) and 262 White women born in the UK (WUK). The results were analysed in relation to demographic and social data. RESULTS: BBB women were significantly less likely to be VZV seropositive at all ages than both BUK and WUK women. However, the odds of a Bangladeshi-born woman being seropositive increased by 1.04 for each year under the age of 15 spent in the UK. In contrast, antibody concentrations were significantly lower in ethnic Bangladeshi women, irrespective of country of birth. White, but not Bangladeshi women, showed evidence of antibody boosting over time despite the latter having more exposure to children. CONCLUSION: Geographical location during childhood is the major influence on age of primary infection with VZV while the level of antibody is related to ethnicity. Since the risk of re-infection with VZV following both natural infection and vaccination is increased as antibody concentrations fall, these results have implications for VZV vaccination programmes particularly in non-White populations.

Development and evaluation of Varicella zoster virus ELISA for oral fluid suitable for epidemiological studies.

An enzyme-linked immunosorbent assay (ELISA) for detection of Varicella zoster virus (VZV) antibodies in oral fluid is described. The assay was optimised and evaluated using paired serum and oral fluid from healthy adult volunteers (n = 205) and preschool children (n = 98), oral fluid samples collected for routine measles, mumps and rubella testing (n = 537) and samples from a study of atopic dermatitis (n = 252). As chickenpox is predominantly a childhood disease and most adults are immune, it was crucial to have samples from children aged 1-5 years to evaluate the assay. Mixture modelling of the oral fluid results was used to determine the optimum cut-off, sensitivity and specificity of the assay. Compared to paired sera tested by the same ELISA the sensitivity of the oral fluid assay was 93% and specificity 95.7% overall, varying slightly with age group. The assay was shown to have good potential for use in large-scale epidemiological studies.

The molecular epidemiology of varicella-zoster virus: evidence for geographic segregation.

Of 75 varicella-zoster virus (VZV) isolates obtained from patients in Africa, Asia, and the Far East, 74 (98.6%) were found to be positive for a BglI restriction site in gene 54. By contrast, <22% of strains from patients in the United Kingdom and in North and South America were positive for the BglI restriction site. Viruses positive for BglI were significantly more common in zoster occurring in patients of nonwhite origin (P<.05). Irrespective of the country in which the sample was obtained, 98% of strains positive for BglI clustered within a single phylogenetic group, which we termed "group A"; the exception was 1 strain that appeared to be recombinant genotype C/A. We used the BglI site to examine both the spread of type A viruses in the United Kingdom and the patterns of VZV infections within persons from different ethnic groups who grew up in the United Kingdom or abroad.