Shuangshuang Che, Bo Zhang, Qin Zhang, Xincai Wei, Peng Wu, Hongbin Lan, Xueqian Lin

Abstract This study analysed the epidemiological characteristics of the syphilis epidemic in Nanchong City of Sichuan Province to provide a theoretical basis for syphilis prevention and control. The syphilis epidemic data reported in the China Disease Control and Prevention Information System within the Nanchong City from 2017 to 2021. Chi-squared test and linear trend Chi-squared test were used to analyse the distribution of syphilis in terms of time,region,population and development stage. From 2017 to 2021, a total of 16,819 syphilis cases were reported in Nanchong City, with an average incidence rate of 52.35 × 10-5. The number of reported cases and the incidence rate showed an increasing trend and then decreasing. There were 8315 males with an incidence rate of 51.45 × 10-5 and 8504 females with an incidence rate of 53.26 × 10-5. The male to female ratio is 0.98:1. The age group is mainly middle-aged and older people over 50 years old. Occupations are primarily farmers, houseworkers and unemployed workers. Conclusions: In the past five years, the incidence of syphilis has first increased and then decreased in Nanchong City,but the epidemic situation remains severe.In order to effectively curb syphilis epidemic as soon as possible. It is necessary to increase comprehensive intervention efforts for high-risk groups, propose feasible measures to control the epidemic. An effective coordination mechanism needs to be established and extensively mobilise the whole society to participate in publicity and cooperate. At the same time, develop an efficient follow-up service to control the spread of syphilis and to improve the health of syphilis patients.

Keywords: Syphilis; epidemiology; control measures; Nanchong; China

Introduction

Syphilis is a sexually transmitted disease (STD) caused by Treponema pallidum, The main routes of transmission are sexual contact,blood and mother-to-child transmission. Serious harm to human tissues and organs [1]. It is a Class B infectious disease that is legally reported in my country. The report data on China’s Class A and B statutory infectious disease show that syphilis incidence ranks third in the country [2]. When studying the occurrence, development and prognosis of diseases, we should not only pay attention to physiological factors, but also do not ignore the influence of psychological factors that reflect social factors, and combine the natural and social attributes of human beings to investigate. Only in this way can we reveal the essence of life vitality, to find out the regularity of human’s struggle against disease. Syphilis as a typical representative of venereal diseases. In recent years, the syphilis epidemic has become an important public health and social problem in the world and in China question.Timely, accurate and scientific analysis of surveillance data to fully grasp the epidemiological characteristics and risk factors of the disease is crucial for disease prevention and control [3].Syphilis not only threatens people’s physical and mental health and safety, but also threatens the health of the next generation. Medical staff are the front-line personnel who find syphilis cases and provide

patients with knowledge of syphilis prevention. Their knowledge and mastery of syphilis knowledge are not only related to the treatment effect of patients, but also a key factor in determining the implementation effect of syphilis transmission prevention projects. Since 2005, China has implemented an online direct reporting system for infectious diseases. Nanchong City is a large city with a large number of floating population and migrant workers. It is of great significance to improve the population’s awareness to prevent the spread of syphilis and to minimise the impact of syphilis on the health of key populations such as women and children. It is of great significance to improve women and children’s quality of life and health. In order to grasp the epidemiological characteristics and trend of syphilis in Nanchong City, late syphilis occurs about two years after infection and is highly destructive to the body. It can damage vital organs such as the eyes, cardiovascular, skeletal, and nervous systems, resulting in disability and death. This paper analyses the syphilis epidemic data from 2017 to 2021 and provides a basis for formulating prevention and control strategies and raising public awareness.

Materials and methods

Objects

Information on syphilis patients was collected using the Infectious Disease Surveillance Information System of China Information System for Disease Control and Prevention. China Information System for Disease Control and Prevention is a real-time network monitoring system for notifiable infectious diseases established by the Chinese Center for Disease Control and Prevention. With the approval of the Center for Disease Control and Prevention of Nanchong City, we downloaded the historical report data.Data are collated and analysed by downloading historically reported data. The research subjects selected syphilis cases at their current address in Nanchong City from January 1, 2017, to December 31, 2021. Diagnosis of syphilis cases was performed according to the Diagnostic Criteria for Syphilis (WS 273-2018).Demographic data come from Nanchong Statistical Yearbook.

Data analysis

Data processing and statistical analysis were performed using Excel 2016 and SPSS 17.0 software. The incidence of syphilis patients was analysed by trend Chi-squared test. P＜0.05 was considered to be statistically significant.

Results

Syphilis case reporting

During the five years from 2017 to 2021, a total of 16,819 syphilis cases were reported in Nanchong City, with a sex ratio of 0.98:1.With the exception of 2021, the reported incidence of syphilis in women was lower than in men, and the reported incidence in women was higher than in men in all other years. The total reported annual average incidence of females (53.26 × 10-5) was slightly higher than that of males (51.45 × 10-5). In each year, the reported incidence rate of gender showed a trend of first increasing and then decreasing, and the difference was statistically significant (Table 1).

Staging of syphilis patients

Most cases of syphilis reported each year were latent syphilis, and the composition ratio increased year by year. The average composi-tion from 82.12% in 2017 to 91.24% in 2021, Followed by a slight decrease in the proportion of primary syphilis. The incidence of primary syphilis each year is higher than that of secondary syphilis,while tertiary syphilis and fetal syphilis are relatively rare. There were relatively constant distribution characteristics in each year (Table 2).

Table 1. Incidence of syphilis by gender in Nanchong City from 2017 to 2021

Table 2. Reported incidence of syphilis in Nanchong City from 2017 to 2021

Regional distribution of syphilis patients

The reported cases of syphilis are mainly distributed in Nanbu County and Langzhong City, with a total of 6,821 cases were reported accounting for 40.56% of the total number of syphilis reports.Peng’an County, Xichong County and Gaoping District reported relatively few cases. The average annual incidence rate was higher in Langzhong City, Nanbu County and Shunqing District (Table 3).

Age distribution of syphilis patients

The incidence and composition ratio of the age group under ten years old decreased year by year from 2017 to 2020; In 2020, no cases were found under the age of ten years old, and the proportion of the age group under the age of ten in 2021 was 0.07%. The incidence and composition ratio of the age group over 50 years increased; The composition ratio of the other age groups didn’t change much. In 2021, the incidence trend is still dominated by middle-aged and older people over 50 years old, and the incidence and composition ratio has increased. The age is mainly concentrated in 45-80 years old, accounting for 60.91%; The middle-aged and older people over 50 years old accounted for 62.56%. The 60 years old above age group accounted for 44.40%(Figure 1).

Occupational distribution of syphilis patients

Various occupations were reported from 2017 to 2021, and the number of reported occupations as farmers increased more from 1940 to 2957 cases. Each year, farmers, housework and the unemployed are the main ones, and the composition ratio of each occupation changes little. The top three are farmers accounting for 54.48%, housework and unemployed accounting for 26.07%, and retirees accounting for 6.29% in 2021 (Figure 2 and Figure 3).

Discussion

Syphilis patients not only suffer from physical pain but also suffer from heavy pressure and burden mentally. Three months after Treponema pallidum infection, symptoms such as mild fever, fatigue and loss of appetite appeared throughout the body. Then, it causes red rashes or mucosal erosions on the body and raised eczema. The clinical manifestations are complex and diverse, and it is easy to cause misdiagnosis and missed diagnosis. It has become a serious social and public health problem [4, 5]. With the transition to the bio-psycho-social medical model, the role of psychological factors in the occurrence of diseases has attracted more and more attention,especially the specific group of patients with sexually transmitted diseases [6]. Therefore, psychological counselling should be widely carried out for STD patients to prevent, detect, and treat psychological problems as soon as possible to improve the quality and effect of STD treatment such as syphilis.

Through the data analysis of the citywide’s epidemic network direct reports, the syphilis epidemic in our city as a whole is in a trend of rising first and then falling from 2017 to 2021. The annual growth trend before 2019 is consistent with the reported incidence trend of syphilis in Xiqing District of Tianjin city and Qinghai Province[7,8]. The reasons for the increase may be related to the following factors. First, the syphilis screening for various groups of people has increased yearly, and the number of screened syphilis-positive people has increased yearly. In recent years, while carrying out AIDS publicity work, it is also publicising sexually transmitted diseasessuch as syphilis and hepatitis C. Various groups of people are aware of and take the initiative to test for syphilis. In addition to expanding HIV testing, medical institutions also test for syphilis. Secondly, due to the standardised diagnosis of syphilis and the strengthening of the management of infectious disease epidemic reporting, the number of syphilis case reports has increased. The level of diagnosis and treatment of some medical staff is not high, and insufficient attention to this work may also be an influencing factor. Occasionally, a small number of institutions have inaccurate grasp of the laboratory diagnostic criteria for syphilis, and syphilis case reports are not standardized, overreported and repeated.

Table 3. The number and incidence of cases in counties and urban areas of Nanchong City from 2017 to 2021

Figure 1. Syphilis is distributed by all ages in 2017-2021

Figure 2. Occupational distribution of syphilis in Nanchong from 2017 to 2021 about Composition ratio(%)

The data shows that the syphilis cases are dominated by recessive syphilis in Nanchong City, accounting for 85.81%, which is consistent with the results of other related domestic studies [9-12]. It may be related to seeking non-professional doctors, leading to misdiagnosis and lack of formal treatment. It was discovered that large number of physical examinations of undiagnosed and unreported early syphilis (including primary and secondary syphilis) evolved into asymptomatic but infectious latent syphilis.

A total of 2,957 syphilis cases were reported in Nanchong city in 2021 (including 2,698 cases of recessive syphilis, accounting for 91.24%). And the reported incidence rate was 45.95 × 10-5, which was lower than the average annual reported incidence of syphilis reported 56.68 × 10-5in Anning City [13]. However, it is higher than the reported annual average incidence rates of 25.96 × 10-5and 37.13× 10-5in Xiqing District of Tianjin and Wenzhou City, respectively [7,14]. In 2020-2021, the syphilis epidemic showed a downward trend.Except for stage III syphilis and fetal syphilis, the number of reported cases of other types of syphilis decreased. The first reason for the decline is that it may be affected by the control of the Novel Coronavirus Pneumonia Epidemic and the people’s increased awareness of protection. It is necessary to further implement and strengthen case management. Second, a small number of medical staff didn’t perform their duties and lacked consulting skills, and the service ability and quality of grass-roots personnel needed to be further improved.In terms of regional distribution, there are large regional differences in syphilis reports in various counties (cities, districts) in our city from 2017 to 2021. Nanbu County and Langzhong City reported most cases, which may be related to the increase in migrant workers in recent years. The age group is mainly in the age group over 50 years old, and the incidence and composition ratio have both increased; It is suggested that we should continue to increase the publicity of health education on the prevention and treatment of syphilis,gonorrhoea and other sexually transmitted diseases (especially highrisk and vulnerable groups). To improve the self-protection ability of the crowd, and especially strengthen knowledge training for migrant workers and the elderly to improve the city’s quality of work to prevent syphilis transmission.

There are slightly more women than men in all syphilis cases,with a male-to-female ratio of 0.98:1. Which is consistent with that reported by the Jinning District of Kunming City and so on [15,16].However, this is contradicted by reports from Nanchang and Qingyuan [17, 18]. Because women’s immunity is lower than that of men, they are more susceptible to syphilis, resulting in an upward trend in female syphilis cases. The occupational distribution showed that farmers, houseworkers, the unemployed and retired people accounted for a higher proportion, which was consistent with the occupational distribution of syphilis reported in Jinzhong City, Shanxi Province and other places [2,19,20]. It may be related to the high mobility, low education level, less daily publicity and intervention,and weak awareness of STD protection. Prompt and special attention should be paid to the prevention and control of syphilis in such occupational groups.

Limitations of this study: The influencing factors of morbidity have not been further researched, and targeted prevention and control strategies need to be deeply analyzed. The new coronavirus pneumonia epidemic affects the real situation of the city to a certain extent.

Conclusion

Finally, although the syphilis prevention and control work has achieved specific results in Nanchong City, the syphilis epidemic situation is still severe. Based on the actual situation of our city, we will focus on the following work for the prevention and control of syphilis in the future: Increase comprehensive interventions for key groups, such as needle exchange and methadone replacement therapy for injecting drug users; Promote issue condoms to prostitutes and clients of prostitutes and so on. To reduce their risky behaviour and reduce the spread of syphilis; Strengthen leadership, strengthen the construction of syphilis and gonorrhoea prevention and control teams, strengthen technical training, improve the professional level of professional and technical personnel were needed. Promoting the comprehensive and in-depth development of prevention and control work in the city’s nine counties (cities, districts). We will set up a work leading group, organise meetings promptly, study the problems existing in work on time, and put forward rectification opinions to ensure the smooth development of this work. Extensively mobilise the whole society to cooperate closely in the division of labor and cooperation. An effective coordination mechanism and strict information reporting system were established. Tracking services will be standardised to control the spread of the syphilis epidemic and improve the health of syphilis patients.