Human Papillomavirus Prevalence and Genotype Distribution in Dongguan, China

Abstract

Introduction:

Cervical cancer is strongly associated with human papillomavirus (HPV) infection. In this retrospective study, we analyzed the data of individuals who were tested for HPV at Binhaiwan Central Hospital in Dongguan.

Methods:

We retrospectively analyzed the data of 73,149 participants who underwent HPV examination at Binhaiwan Central Hospital in Dongguan. All participants were tested for HPV genotypes. We subsequently analyzed the infection rate and evaluated the distribution of HPV using the Chi-square test.

Results:

The results suggest that the five most common HPV infection genotypes for men in the Dongguan area are different from those for women. The five most common high-risk HPV infections in women were the HPV52, 16, 58, 53, and 68 genotypes, whereas the five most common genotypes in men were HPV52, 16, 51, 58, and 39. The highest HPV infection positivity rate for female patients (31.68%) was in the 31–40 year age group, whereas the highest HPV infection positivity rate for male patients (40.47%) was in the 21–30 year age group.

Conclusions:

These findings provide a theoretical basis for epidemiological investigations, clinical prevention, and treatment of HPV infection and HPV vaccination in the region. The results could provide valuable information for healthcare professionals and policymakers to develop targeted prevention and screening strategies for reducing the burden of HPV-related diseases in this population.

INTRODUCTION

Human papillomavirus (HPV) infection is a common genital tract infection that can cause a series of lesions on the skin/mucous membranes of the genital tract and is closely related to cervical cancer.[1,2] Currently, more than 200 types of HPV have been identified, more than 50 of which are associated with human genital tract infections.[3] Depending on their carcinogenicity,[4] according to IARC, they can be categorized as high-risk HPV (HR-HPV), including genotypes HPV16, HPV18, HPV31, HPV33, HPV35, HPV39, HPV45, HPV51, HPV52, HPV53, HPV56, HPV58, HPV59, HPV66, HPV68 and HPV70, and low-risk HPV (LR-HPV), including genotypes HPV6, HPV11, HPV40, HPV42, HPV43, HPV44, HPV54, HPV61, HPV72, HPV81, and CP6108.[5] Of these genotypes, 15 are high-risk infection types. These high-infection types are the main cause of cervical intraepithelial neoplasia (CIN). CIN is a precancerous lesion of cervical cancer that eventually progresses to invasive carcinoma of the uterus. The main low-risk types are HPV6 and HPV11, which are primarily associated with benign lesions such as human external genital lesions and condylomas.[6]

Cervical cancer is a common gynecological tumor and has become the second-most common malignant tumor in the world after breast cancer among all early-stage tumors in older women worldwide.[7] It is a serious threat to women’s life and health. Studies have reported that in Guangzhou city, Guangdong Province, HPV genotypes 52, 16, 58, 51, and 53 have high risks of HPV infection.[8] The prevalence of HPV varies considerably across regions, and in the Pearl River Delta region of China, there is high population mobility and many foreigners.[9] The internally migrant Chinese population is an understudied demographic group in this context. This study, which was conducted in Dongguan, China, represents one of the pioneering investigations of people with HPV within this migrant community.[10] Therefore, it is necessary to understand the prevalence of HPV in the Dongguan region. Its incidence rate is on the rise, specifically in the younger population. Regular screening and scientific follow-up management play key roles in the prevention and treatment of this disease. Therefore, determining the rate and characteristics of HPV-positivity in the Dongguan area is highly important for the prevention and treatment of cervical cancer.

The objective of this study was to identify more targeted strategies for the prevention, treatment, and elimination of cervical cancer and HPV-related diseases. In this study, we conducted a comprehensive and in-depth exploration of the patterns of HPV infection using data from 73,149 participants. The content of this study is thorough and has significant implications for guiding clinical practice.

Data sources

In this study, data from 73,149 patients from the Binhaiwan Central Hospital in Dongguan City between July 2015 and July 2022 were retrospectively analyzed. The local ethics committees approved each of the studies, and the patients were divided into two groups: men and women. HPV testing was used as a routine examination for suspected gynecologic conditions in higher-income families. HPV positivity was identified by polymerase chain reaction (PCR), and 17 HPV genotypes were tested, including 15 HR-HPV genotypes (HPV 16, 18, 31, 33, 35, 39, 45, 51, 52, 53, 56, 58, 59, 66, and 68) and 2 LR-HPV genotypes (HPV 6 and 11). The test kit was purchased from SANSURE BIOTECH INC for the High-risk HPV Nucleic Acid (Typing) Diagnostic Kit (PCR-Fluorescent Probing) and HPV (Type 6 and 11) DNA Fluorescence Diagnostic Kit (PCR-Fluorescent Probing). Owing to changes in the test kits, specific genotypes 6 and 11 can be differentiated from 2015 to 2017, but 6 and 11 cannot be differentiated from 2017 to 2022; thus, all LR-HPVs are denoted as 6/11, and the other genotypes are as described.

Statistical analysis

The prevalence of HPV infection, the presence of single or multiple HPV infections, and HPV genotypes were estimated through binomial distribution analysis. A Chi-square test was performed to compare the differences in the infection rates (the number of positive individuals among the corresponding whole population) of HPV or HR-HPV and the ratio of positive individuals (the number of positive individuals among the corresponding population) of HR-HPV or LR-HPV among the various patients. The Bonferroni method was used to adjust the P value for paired comparisons between the two groups. The time trend of the positive rate over the years was analyzed using the Mann–Kendall trend test. Statistical tests were two tailed. Statistical analysis was performed using R. These data were also stratified by age (≤20 years, 21–30 years, 31–40 years, 41–50 years, 51–60 years, and ≥ 61 years). Count data are expressed as frequencies or percentages. For all the statistical analyses, the P values were two-sided, and P < 0.05 was considered statistically significant. The statistical analyses were performed with SPSS version 13.0 (SPSS, IBM, NY, USA).

METHODS

Study subjects: The study population included patients who underwent routine cervical exams at Binhaiwan Central Hospital between 2015 and 2022 in Dongguan, China. All patients underwent genotyping for HPV and cervical cytological evaluation combined with colposcopy. The exclusion criteria were pregnancy, total hysterectomy, systemic infection or autoimmune diseases, surgery for uterine diseases within 3 days, or other cancers.

Specimen collection: Patients were asked not to urinate for 2 h before sampling. (1) The attending physician used a speculum and a cervical sampler to collect a sample of exfoliated cervical cells or male urethral secretions, which were preserved in a cytochemical preservation solution for examination. The standardized collection method for women is as follows: before sampling, excess secretions from the cervix were removed, the cervical brush was held firmly against the mucosa of the cervix, the cervical brush was gently rubbed to rotate the swab clockwise 3–4 times to obtain secretions and exfoliated cells, and the sample was placed in a sterile sample tube containing cytoplasmic preservation solution. The excess brush handle was removed at the mouth of the tube and the tube was sealed. For men, male urethral secretions were collected, and the excess secretions from the urethra were gently wiped clean with a cotton swab before sampling. The cotton swab was replaced with a saline-moistened cotton swab that was tightly applied to the mucous membrane of the urethra, and the samples were rotated with slight force for 2 weeks before the collected swabs were placed in sterile sample collection tubes and sent for testing in a closed container. (2) Sample processing: In the sample processing room, nucleic acid extraction reagents were used for nucleic acid release from exfoliated cervical cell samples. (3) PCR reagent preparation and PCR amplification: The PCR mixture was prepared according to the instructions of the kit (purchased from SANSURE BIOTECH INC); 25 µL of the treated sample was added to each of the PCR tubes, and the mixture was mixed with 25 µL of nucleic acid release reagent. The samples were subsequently added, after which PCR amplification was started. The PCR program was as follows: initial denaturation step at 95°C for 9 min; followed by 40 cycles of 95°C for 20 s, 55°C for 30 s, 72°C for 30 s, and a final extension at 72°C for 5 min. The PCR results were automatically saved after the reaction; the start value, end value, and threshold value of the baseline were adjusted according to the analyzed image; a click analysis was performed; and then the Ct value was recorded. Genotyping was performed through hybridization of the PCR products to a gene chip containing 15 h-HPV and 2 LR-HPV genotype-specific oligonucleotides, and the genotype was analyzed using SANSURE BIOTECH INC. This kit did not require the DNA in the sample to be extracted separately during the entire experimental process; instead, the sample was mixed directly with the nucleic acid-releasing agent, which can be used as the template for PCR amplification, avoiding environmental contamination in the process of conventional nucleic acid extraction. This detection system involved uracil DNA glycosylase + dUTP anticontamination measures, which fully degrade the possible contamination products, avoiding false-positive results. The chip can identify 15 h-HPV genotypes and 2 LR-HPV genotypes. The final results were detected by colorimetric changes on the chip under direct visualization, and blue – purple spots were recognized as positive for HPV.

For quality control, PCR amplification of the samples was performed in strict accordance with the manufacturer’s instructions; hybridization, color development, and other treatments were performed in strict accordance with the operating procedures of the manual. The results were interpreted on the premise that the CC point (coloring quality control point; positive means the hybridization process is normal) and PC point (internal reference point; positive means the sampling, DNA extraction, and PCR process is normal) all presented blue colouration.

RESULTS

Human papillomavirus prevalence among 73,149 patients

Among the 73,149 patients, 13,367 (18.3%) were positive for HPV infection, among whom 9171 (68.6%) were positive for a single-genotype infection and 4196 (31.4%) for multiple infections [Figure 1].

Figure 1.

Human papillomavirus prevalence among 73,149 people

Human papillomavirus infection and genotype distribution

A total of 73,149 patients were investigated, of whom 9171 were positive, resulting in a total infection rate of 12.54%. The five most common high-risk genotypes were HPV52, 16, 58, 53, and 68, with infection rates of 4.68%, 2.95%, 2.45%, 1.75%, and 1.70%, respectively. The LR-HPV infection rate was 4.45% (4334/48,573) [Figure 2c]. Among the 69,024 female patients investigated, of whom 11326 were positive, yielding an infection rate of 16.41% in this group. The top five HR-HPV genotypes for female patients were HPV52, 16, 58, 53, and 68, with infection rates of 4.58%, 2.76%, 2.36%, 1.67%, and 1.59%, respectively. The LR-HPV infection rate among females was 2.38% [Figure 2a]. There were 4125 male patients investigated, 2041 of whom were positive, resulting in an infection rate of 49.48%. The five HPV genotypes with the highest infection rates among males were HPV52, 16, 51, 58, and 39, with infection rates of 6.38%, 6.18%, 4.02%, 3.95%, and 3.66%, respectively. The LR-HPV infection rate among males was 39.15% [Figure 2b]. This large gap between male and female infection rates is due to sample error, with approximately 17 times as many women as men being tested. Therefore, to analyze the characteristics of HPV infection in males in the Dongguan area, more data need to be collected, which will be one of the directions of our future research.

Figure 2.

Human papillomavirus (HPV) Infection and genotype distribution in Dongguan from 2015 to 2022. (a) HPV infection and genotype distribution in females, (b) HPV infection and genotype distribution in males, (c) total HPV infection and genotype distribution. The first 15 were high-risk HPV genotypes, and the last was a low-risk genotype

Age distribution profile of patients with human papillomavirus infection

When the patients were divided according to age into six groups and analyzed within the overall patient population, the 31–40 year age group had the greatest rate of HPV infection positivity, at 31.96%. The 21–30 year age group had the second highest percentage, at 31.62%. This distribution pattern was the same as that of the female patient group. The HPV infection positivity rates of female patients were 31.68% and 30.03% in the 31–40 and 21–30 years age groups, respectively; however, in the male patient group, the 21–30 year age group had the highest HPV infection positivity rate, at 40.47%. The 31–40 year age group was the second largest at 33.51% [Figure 3].

Figure 3.

Age distribution profile of human papillomavirus (HPV) infection in Dongguan in 2015–2022. (a) Age distribution profile of HPV infection in women, (b) Age distribution profile of HPV infection in men, (c) Overall age distribution profile of HPV infection

Genotype distribution in the human papillomavirus-positive population in the female group

Because of the large gap between the male and female samples in this study, with the female samples being much more numerous than the male samples, the HPV genotype infections in the different age groups in the table below are represented by the female group. As presented in Table 1, the most common genotypes of HPV infection were HPV52 (19.55%, 3164/16186), HPV16 (11.75%, 1902/16186), HPV6 or 11 (10.14%, 1642/16186), and HPV58 (10.08%, 1632/16186).

Table 1.

Distribution of different types of human papillomavirus in each age group (women)

Age groups	≤20	21–30	31–40	41–50	51–60	≥61	Total
HPV16	118	557	551	451	172	53	1902
HPV18	47	184	202	133	44	8	618
HPV31	30	100	118	82	38	7	375
HPV33	37	139	153	152	66	20	567
HPV35	14	62	76	54	21	6	233
HPV39	65	335	273	207	106	11	997
HPV 45	12	50	36	37	11	5	151
HPV51	78	392	300	173	80	10	1033
HPV52	162	998	934	726	284	60	3164
HPV56	52	169	204	149	58	13	645
HPV58	85	449	516	397	146	39	1632
HPV59	39	124	91	74	27	2	357
HPV68	59	336	354	247	83	21	1100
HPV53	55	303	358	299	111	30	1156
HPV66	54	186	189	131	49	5	614
HPV6 or 11	203	616	464	258	89	12	1642
HPV	1110	5000	4819	3570	1385	302	16,186

HPV: Human papillomavirus

Human papillomavirus positivity rates from 2015 to 2022

Among the 73,149 patients, the positive rate of HPV infection decreased annually from 2015 to 2022, with the rate of infection in female patients ranging from 22.87% to 13.17% [Figure 4].

Figure 4.

Human papillomavirus positivity rates from 2015 to 2022. HPV: Human papillomavirus

DISCUSSION

The prevalence of HPV infection and its genotype distribution have been reported in different countries and regions around the world,[11] and there are notable geographic variations in the prevalence of HPV, which is related mainly to factors such as ethnicity, regional differences, economic level, medical care level, environment, and living habits.[12] Therefore, it is important to analyze the characteristics of HPV infection in the region to facilitate the development of prevention and treatment strategies to meet local needs, and these findings are conducive to this goal. The genotypes of HPV infection in this study were more consistent with those of other developed cities in China, such as those in the Wuhan, Guangzhou, and Ningbo regions (HPV52, HPV16, and HPV58).[13] Internationally, the incidence of HPV ranges from 6% in Southeast Asia to 32% in East Africa.[14] The prevalence of HPV infection among the 73,149 patients in this study was 18.27%, which is higher than that reported in Malaysia and Southeast Asia (14.00%).[15] However, it is lower than that reported in Argentina (30.7%),[16] Mexico (54.17%),[17] and Iran (38.68%).[18] This may be due to insufficient knowledge of HPV healthcare among patients in the Dongguan area. The level of community health knowledge about HPV and the prevalence of vaccination are much lower than those reported in Malaysia and higher than those reported in Argentina, Mexico, and Iran. In the female patient population, monoinfections predominated, but in male patients, multiple infections dominated. Therefore, the focus of HPV infection protection in the Dongguan region needs to be on monoinfection protection and treatment in the female population. It has been shown in the literature that a single HPV infection has a differential effect on the developmental role of cervical cancer. The authors showed that coinfection of HR-HPV with LR-HPV conferred a lower risk of cervical cancer than infection with HR-HPV alone.[19,20] Patients with CIN1 combined with multiple HPV infections have a greater risk of developing CIN2 than patients with single HPV infections do, the authors showed that multiple HR-HPV infections increased the risk of developing CIN lesions compared to a single infection.[21] In our present study, multiple infections are those in which not one infection is categorized as multiple infections, we did not distinguish whether multiple infections with only HR-HPV genotypes or multiple infections with combined HR and LR-HPV. This will be an issue that we need to closely monitor in the future.

Some studies have shown a bimodal pattern of age trends in HPV infection, and the second peak around menopause has been hypothesized to be associated with age effects (i.e. impaired immune response, changes in sexual behavior, or reactivation of latent infections) or birth cohort effects (i.e. particular sexual behavior, and attitudes or contraceptive usage).[22] The reason for this difference may be that Dongguan is a city with a large number of migrant workers and generally employs young people. This should urge government policymakers to increase the promotion of sex education for young people, increase vaccination efforts for people of the recommended age, and popularize free cervical cancer screening for people over 35 years of age.[23] The age distribution of HPV shows that the 21–40 year age group accounts for a large part of the positivity rate of HPV infection, which may be related to the fact that the young group is sexually active and does not pay attention to personal hygiene, which leads to HPV infection.[24] Thus, it is important to carry out appropriate sex education, and young people need to learn to protect themselves and pay attention to their own physical health and safety.

Because of the limitations of the test kits we used, we only detected a total of 15 HR-HPV genotypes instead of the 23 types of HPV test kits that are commonly available on the market today, which may not be as comprehensive for HPV typing in the Dongguan area. The number of male patients is considerably lower than the number of female patients, so HPV infection in Dongguan should be discussed and analyzed in terms of males and females.

In recent years, the cervical cancer vaccine has also been a major social hotspot. Currently, there are bivalent, quadrivalent, and 9-valent HPV vaccines on the market; the bivalent vaccine targets HPV types 16 and 18; the quadrivalent vaccine targets HPV types 6, 11, 16, and 18; and the 9-valent vaccine adds five genotypes–31, 33, 45, 52 and 58–on the basis of the quadrivalent vaccine.[25] HPV vaccines can effectively prevent HPV infection and further reduce the probability of occurrence of cervical cancer.[26] In recent years, with the launch of the 9-valent HPV vaccine, people have gained a better understanding of HPV[27] and more people have begun to pay attention to cervical cancer screening; however, the cervical cancer vaccine can only play a preventive role and does not have a therapeutic effect on patients who have already been infected with HPV.[28] There are some studies that have shown that adjuvant HPV vaccination reduces the risk of recurrence of HPV-related preinvasive diseases. This study highlights the role of prophylactic HPV vaccines in the secondary prevention setting, which could pave the way to a new era in the management of HPV-related diseases.[29] Receiving the vaccine does not mean that individuals will no longer be infected with HPV.[30] Owing to the publicity and increasing popularity of the HPV vaccine in recent years,[31] the infection rate of HPV has shown a decreasing trend in the Dongguan area. This finding shows that the HPV vaccine has played a preventive role to a certain extent. In summary, analyzing the HPV infection situation in a specific region will enable us to more accurately carry out cervical cancer screening and education in the region according to its characteristics, popularize correct health knowledge, and publicize vaccine knowledge to reduce infection risk.

CONCLUSIONS

This study describes the baseline type and age-specific HPV prevalence among females and males in Dongguan, which may provide a baseline HPV prevalence.

The highest rate of positivity was found in the 30–50 year age group. This may be related to women’s awareness of health care and financial independence in this age group; the highest number of tests are also performed in this age group. While postmenopausal women are more susceptible to HPV infection due to lower immunity, the rate of postmenopausal HPV infection is not high in Dongguan due to economic, religious, personal, and family factors. Therefore, there is a need for increased attention and targeted interventions in this age range. We need to better classify patients infected with HPV to provide useful information for prognosis and tailor the most appropriate treatment regimen for these patients.

Research quality and ethics statement

The present study obtained ethical approval (no. Z2025001) from the Ethical Committee of Binhaiwan Central Hospital of Dongguan, in accordance with the Helsinki Declaration. Due to its retrospective design, a waiver of participant informed consent was granted by the Ethical Committee of Binhaiwan Central Hospital of Dongguan.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

This work was supported by grants Dongguan Science and Technology of Social Development. Program 20231800940062 (Shayan Chen was the recipient) and grant BS2023001 (Shayan Chen was its recipient) from the Doctoral Research Foundation of Binhaiwan Central Hospital in Dongguan.