At the time of varicella vaccine introduction in the United States, an estimated 4 million episodes of varicella occurred annually. This survey of varicella seroprevalence is the first to describe immunity to a vaccine-preventable disease prior to vaccine introduction in the United States population. The objective of this analysis is to describe patterns of naturally-acquired varicella and understand characteristics associated with infection in the varicella vaccine-naive United States population. A nationally representative cross-sectional health examination survey that included venipuncture was conducted among 21,288 U.S. participants aged 6 years and older from 1988 through 1994. Serologic evidence of varicella-zoster virus infection was measured by enzyme immunoassay of varicella-zoster virus-specific IgG antibody. The seroprevalence of IgG antibody to varicella-zoster virus increased from 86.0% in children aged 6 through 11 years to 99.6% in adults aged 40 through 49 years. Immunity to varicella remained at 99% or higher in Americans aged 50 years and older. Among persons aged 6 through 19 years, non-Hispanic black children were 40% less likely to be seropositive compared with white children (odds ratio [OR], 0.6; 95% confidence interval [CI], 0.4-0.8). Among young adults aged 20 through 39 years, women with a history of live birth (OR, 4.3; 95% CI, 2.1-8.7) and married men (OR, 2.7; 95% CI, 1.2-5.7) were more likely to have naturally-acquired immunity to varicella. This study found that, prior to use of varicella vaccine in the United States, age, race, and marital characteristics were independently associated with naturally acquired varicella. Future varicella serosurveys in Americans will provide essential information to interpret the population impact of varicella vaccine.
To evaluate the relationship between Helicobacter pylori infection and the subsequent risk and severity of endemic Vibrio cholerae O1 diarrhea among rural Bangladeshis, 285 children and adults with cholera (cases) and 881 contemporaneously selected community controls were studied. Cases and controls were contrasted for H. pylori infection, as manifested by serum IgG anti-H. pylori antibodies. Although the overall risk of cholera was not significantly increased among H. pylori-infected subjects, the risk of cholera of life-threatening severity was significantly elevated (relative risk [RR] = 1.61; 95% confidence interval [CI] = 1.07-2.42). A significant increase in the risk of severe cholera was seen in subjects who lacked natural serum vibriocidal antibodies (RR = 2.88; 95% CI = 1.28-6.48) but not in those with such antibodies. Thus, H. pylori infection was associated with a significant increase in the risk of life-threatening cholera, but only among persons lacking natural vibriocidal immunity.
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