QUEBEC CITY – The incidence of herpes simplex virus type 2 in the United States has remained stable within gender and ethnic groups over the past two decades, with young black women remaining at the highest risk for infection, according to an analysis of data from the National Health and Nutrition Examination Surveys for 1988-1994 and 1999-2008.
Herpes simplex virus type 2 (HSV-2) infections have a 16% seroprevalence among 14- to 49-year-olds in the United States, said Dr. Sarah M. Gerver of Imperial College, London, who presented the findings at a congress of the International Society for Sexually Transmitted Diseases Research.
Dr. Gerver and her associates at Imperial College and the Centers for Disease Control and Prevention in Atlanta combined NHANES data with a predictive model to estimate HSV-2 incidence per 100 person-years at risk.
Overall, the age-adjusted incidence rates over the past 20 years were stable in all sex and ethnic groups with two exceptions, the researchers noted. Incidence rates in Mexican-American women and non-Hispanic white women had decreased after 2001 and 2002, respectively.
The age-adjusted incidence of HSV-2 in non-Hispanic white men, non-Hispanic black men, and Mexican-American men remained stable at approximately 0.4, 1.4, and 0.7 per 100 person-years at risk, respectively. Non-Hispanic black women had the greatest incidence of HSV-2, which held steady over the study period at approximately 2.2 per 100 person-years at risk.
The incidence rate among 25-year-old non-Hispanic black women was more than 13 times greater than in white men of the same age, the researchers noted.
From 1988 to 2008, HSV-2 incidence rates peaked between ages 25-35 years for all sex and ethnic groups with the exception of Mexican-American men, for whom the incidence remained stable by age.
In 2007-2008, the most recent year included in the study, an estimated 753,519 new HSV-2 infections occurred among 14- to 49-year-olds in the United States, including 392,208 in men and 361,311 in women. Approximately 53% of the new infections in men occurred in non-Hispanic whites, and half of these occurred in men aged 18-29 years.
More than half of the HSV-2 infections in women occurred in those aged 14-24 years (204,550); including 40,520 in girls aged 14-17 years and 164,030 in young women aged 18-24 years.
And among women, "nearly 60% of all new infections were in non-Hispanic blacks, a group that accounts for less then 15% of the female population [in the U.S.]," the researchers noted.
The findings were limited by the researchers’ assumption of perfect comparability of the HSV-2 seroprevalence estimates across age, race, and time. But the stability of the long-term trends in HSV-2 incidence suggests a need for more targeted intervention programs, especially for those at highest risk, the researchers said.
"This information on the detailed distribution of new infections can help improve the efficiency of interventions," they wrote.
The researchers reported having no financial conflicts to disclose.