Prevalence of human papillomavirus infection of 65,613 women in East China

The infection with human papillomavirus (HPV) is strongly associated with genital disease. Type-specific persistent infection with high-risk (HR) HPV is the major reason of cervical squamous intraepithelial lesions as well as cervical cancer [1‐3]. According to its relationship with cervical cancer and precancerous lesions, HPV genotypes are divided into HR-HPV and low-risk (LR) HPV genotypes [4]. These different HPV genotypes have different pathogenicity [5]. The HR-HPV genotypes may lead to cervical carcinogenesis, while the LR-HPV are associated with benign or low-grade changes in cervical cells, such as genital warts [6, 7].

There are many reports on the prevalence of HPV in different populations. The prevalence of HPV infection varies greatly by country, region within country, and population [8, 9]. Therefore, understanding the prevalence characteristics of HPV in different regions is very important for the early detection and prevention of local cervical cancer. In the present study, we made a comprehensive analysis of the prevalence characteristics of HPV in both outpatient women and healthy women who were recruited from Jiangsu, China.

Epidemiological studies had shown that persistent cervical HR-HPV infection is correlated with an increased risk of developing a high-grade cervical intraepithelial lesion (e.g., cervical cancer) [11]. Fortunately, the successful development of HPV vaccines would help to prevent the occurrence of cervical cancer. Population-based epidemiological data would assist to develop HPV vaccines for a specific population.

Most of the previous researches on HPV epidemiology were only based on outpatient samples. Since the outpatients usually come to the hospital for some medical problems, the HPV prevalence is different from that of healthy women who participate in normal medical examinations. In our study, both outpatients and healthy participants were recruited from Jiangsu, China. In the 45,736 outpatient women, the prevalence of HPV was 17.7% and the HR-HPV prevalence was 15.7%. Compared with similar studies in China, the prevalence in our study was higher than that in Beijing (9.9%) [12] and Yunnan (12.9%) [13], but lower than that in Fujian (38.3%) [14] and Zhejiang (20.54%) [15]. The different HPV prevalence might be explained by different economic conditions, cultural diversity, geographical regions and survey period. Regarding the 19,877 healthy women, the overall HPV prevalence and HR-HPV prevalence was 10.6 and 10.1%, respectively. It was fully explained that more attention should be paid to the healthy women infected with HR-HPV.

The analysis of HPV prevalence showed that the most commonly identified HR-HPV genotypes were HPV 16, 58, 52, 39 and 18 among the outpatient women. It was different from the healthy women, where HPV 58, 16, 52, 39 and 56 were the five most commonly detected HR-HPV genotypes. The present study showed that HPV16, 58 and 52 were the top three detected HR-HPV genotypes in the two populations, which was similar to the other studies conducted in China, despite the prevalence varied widely [13, 16, 17]. However, it was different from the result of a meta-analysis which summarized global reports and indicated that HPV16, 18 and 45 were most commonly detected genotypes [18]. With a relatively lower prevalence for HPV 18, the vaccines against HPV16, 58 and 52 should be developed for Chinese women.

In the outpatient women with multiple HPV infection, the most commonly identified combinations of HPV types were HPV16 + 58, HPV52 + 58 and HPV39 + 52. While the top three combinations of types were HPV16 + 52, HPV52 + 58 and HPV39 + 58 for the healthy women. It was easy to note that these top three multiple-type infections were the different combinations of HPV 16, 39, 52 and 58. We also found that the vaccines targeting HPV 16/39/52/58 will protect more women in East China, when four HPV types were included in vaccines (Additional file 1: Table S1). If three HPV types were included, HPV 16, 52 and 58 were the recommended combination. When two HPV types were included, HPV 16 and 58 were the recommended combination. 4.6, 3.9 and 2.9% women will be protected by vaccines targeting HPV 16/39/52/58, HPV 16/52/58, and HPV 16/58, respectively. Because the 2v, 4v, and 9v HPV vaccines on the market do not provide protection against type 39, and the different prevalence of HPV types was observed between women in China and the other countries, it is necessary to develop HPV vaccines specific for Chinese women. The HPV vaccines that covered the four additional HR-HPV types (HPV16/39/52/58) may be more meaningful for a HPV vaccination program in China.

The peak prevalence rate of overall HPV, single HPV and HR-HPV was observed in healthy women aged 50–59 years. This was very different from the findings in outpatients of China. Previous studies have reported that HPV prevalence had two peaks in terms of age, while the peak age varied in different studies [19‐21]. The two peaks were generally found in younger and menopausal women. Wang et al. found that HR-HPV infection showed higher rates in younger groups and lower rates in middle age groups and the highest prevalence in individuals aged 15–19 years [22]. Tang et al. reported that individuals aged 21–40 years had highest HPV prevalence [23]. Our data suggested that the highest HPV prevalence was found in outpatient women at the ages of < 20 or ≥ 60 years.

In the present study, we presented the data on the prevalence characteristics of HPV in both outpatient women and healthy women who were recruited from Jiangsu province, east of China. Such data could guide interventions to control prevalence of HPV. Vaccines against HPV58/16/52/39 should be developed for Chinese women specifically. 50–59 years old women had highest HPV prevalence and should be paid more attention.