Among the more than 320 million people in the United States, there was a prevalence estimate of 67.6 million sexually transmitted infections at the time of assessment in 2018, according to the results of an epidemiologic study using multiple data sources, including the National Health and Nutrition Examination Survey (NHANES).
In addition, almost half of the incident STIs occurred in the 15- to 24-year age bracket, according to a report published online in Sexually Transmitted Diseases. Researchers estimated the combined number of prevalent and incident infections of eight STIs in the United States in 2018: chlamydia, gonorrhea, trichomoniasis, syphilis, genital herpes (caused by herpes simplex virus type 2 [HSV-2]), human papillomavirus (HPV), sexually transmitted hepatitis B virus (HBV), and sexually transmitted HIV.
The estimated incidences of these STIs in this update, the first since 2008, were made using more recent data and improved estimation methods to provide updated STI prevalence and incidence estimates for 2018, both overall and by disease. “Having a combined estimate is crucial for policy purposes to illustrate the importance of STIs in the United States,” according to Kristen M. Kreisel, PhD, an epidemiologist at the Centers for Disease Control and Prevention, division of STD prevention, and colleagues.
The number of prevalent and incident infections were obtained by multiplying each STI’s updated per capita estimates by the 2018 full resident population estimates from the American Community Survey.
Detailed results
Chlamydia. The prevalence of chlamydia was estimated using 2015-2018 NHANES data, which was then used to create a modeled prevalence in 2018, according to the authors. There were an estimated 2.4 million prevalent urogenital chlamydial infections among persons aged 15-39 years in 2018; 1.1 and 1.3 million infections among men and women, respectively. Individuals aged 15-24 years comprised 56.7% and 75.8% of all infections in men and women respectively.
Gonorrhea. The prevalence of gonorrhea was estimated using ordinary differential equation based modeling. The number of prevalent urogenital gonococcal infections in 2018 among 15- to 39-year-olds was 209,000 overall; 50,000 in men and 155,000 in women. Of these, 113,000 (54.1%) occurred in 15- to 24-year-olds.
Trichomoniasis. The prevalence of trichomoniasis was estimated using 2015-2018 NHANES data, which was then used to create a modeled prevalence in 2018, according to the authors. The number of prevalent Trichomonas infections among 15- to 59-year-olds was 2.6 million, with 470,000 in men and 2.1 million in women. Persons aged 15-24 years comprised 15.6% of all prevalent infections, according to the authors.
Syphilis. The number of estimated prevalent syphilitic infections (all stages) among 14- to 49-year-old persons in 2018 was 156,000, with infections in men comprising 71.8% of all infections. Infections in both men and women aged 14-24 years accounted for about 25% of all infections, with 36,000 total prevalent syphilitic infections among 14- to 24-year-olds in 2018.
Genital herpes. The prevalence of genital herpes (caused by HSV-2) was estimated using 2015-2018 NHANES data, according to the authors. In persons aged 15-49 years in 2018, there were 18.6 million prevalent HSV-2 infections; 6.4 million among men and 12.2 million among women. Infections in 15- to 24-year-olds comprised 7.1% of all prevalent HSV-2 infections.
HPV. The prevalence of HPV was estimated using 2013-2016 NHANES data, which was assumed to reflect stable prevalence in 2018, according to the authors. Among 15- to 59-year-olds, the estimated number of persons, men, and women infected with one or more disease-associated HPV types in 2018 was 42.5, 23.4, and 19.2 million, respectively, with an estimated 9.0 million (21%) 15- to 24-year-olds infected,
HBV. NHANES 2013-2018 data were used to estimate the prevalence of sexually transmitted chronic HBV infections in 2018, according to the authors. The estimated number of infections among persons aged 15 years and older in 2018 was 103,000 (51,000 men and 52,000 women). There small sample size of individuals aged 15-24 years in the NHANES database made it impossible to obtain an accurate estimate for this group, according to the authors.
HIV. Data from the National HIV Surveillance System were used to estimate the prevalence and incidence of sexually transmitted HIV infections for persons aged 13 years and older in 2018. A total of 984,000 individuals aged 13 years and older were estimated to be living with sexually transmitted HIV at the end of 2018, according to the authors. Nearly 80% were men. In the 13- to 24-year-old age bracket, there were an estimated 45,400 living with sexually transmitted HIV.
Billions in costs
Commenting on the study by the CDC researchers, Raul Romaguera, acting director for CDC’s division of STD prevention, stated in a press release: “There are significant human and financial costs associated with these infections, and we know from other studies that cuts in STI prevention efforts result in higher costs down the road. Preventing STIs could save billions in medical costs, but more importantly, prevention would improve the health and lives of millions of people.”
“About 20% of the total U.S. population had an STI at a given point in 2018, while nearly half of all incident infections occurred in people aged 15-24 years. Focusing STI prevention efforts on the 15- to 24-year-old population may be key to lowering the STI burden in the U.S.,” the researchers concluded.
The authors reported that they had no disclosures.