Increase in congenital syphilis cases and challenges in prevention in Japan, 2016-2017

In Japan, the increase in congenital syphilis (CS) notifications has become a public health concern. We conducted a case series study to describe the characteristics of CS patients and their mothers. Of the 13 mothers who consented to participate, seven had regular prenatal care visits, including four who had tested negative at their first trimester syphilis screening. Only three mothers noted that their partners were tested, with all three partners being diagnosed with syphilis. Raising awareness for syphilis prevention during pregnancy, partner testing, and considering additional syphilis testing at the third trimester of pregnancy during times of increased syphilis prevalence is imperative.

A Genome Epidemiological Study of SARS-CoV-2 Introduction into Japan

After the first case of coronavirus disease 2019 (COVID-19) in Japan on 15 January 2020, multiple nationwide COVID-19 clusters were identified by the end of February. The Japanese government focused on mitigating the emerging COVID-19 clusters by conducting active nationwide epidemiological surveillance. However, an increasing number of cases continued to appear until early April 2020, many with unclear infection routes and no recent history of travel outside Japan. We aimed to evaluate the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genome sequences from the COVID-19 cases that appeared until early April 2020 and to characterize their genealogical networks in order to demonstrate possible routes of spread in Japan. Nasopharyngeal specimens were collected from patients, and reverse transcription-quantitative PCR tests for SARS-CoV-2 were performed. Positive RNA samples were subjected to whole-genome sequencing, and a haplotype network analysis was performed. Some of the primary clusters identified during January and February 2020 in Japan descended directly from the Wuhan-Hu-1-related isolates from China and other distinct clusters. Clusters were almost contained until mid-March; the haplotype network analysis demonstrated that the COVID-19 cases from late March through early April may have created an additional large cluster related to the outbreak in Europe, leading to additional spread within Japan. In conclusion, genome surveillance has suggested that there were at least two distinct SARS-CoV-2 introductions into Japan from China and other countries.IMPORTANCE This study aimed to evaluate the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genome sequences from COVID-19 cases and to characterize their genealogical networks to demonstrate possible routes of spread in Japan. We found that there were at least two distinct SARS-CoV-2 introductions into Japan, initially from China and subsequently from other countries, including Europe. Our findings can help understand how SARS-CoV-2 entered Japan and contribute to increased knowledge of SARS-CoV-2 in Asia and its association with implemented stay-at-home/shelter-in-place/self-restraint/lockdown measures. This study suggested that it is necessary to formulate a more efficient containment strategy using real-time genome surveillance to support epidemiological field investigations in order to highlight potential infection linkages and mitigate the next wave of COVID-19 in Japan.

Syphilis in heterosexual women: case characteristics and risk factors for recent syphilis infection in Tokyo, Japan, 2017-2018

In response to an increase in heterosexual syphilis notifications in Tokyo, we conducted a questionnaire-based case-control study among women aged ≥20 years and sexually active in the past six months who sought a syphilis test in Tokyo during 2017-2018. Cases were women diagnosed as recent syphilis infection based on serological tests. Controls were serologically non-reactive or those with only a past syphilis infection. We described cases and assessed for risk factors of recent syphilis using logistic regression. A total of 524 women (60 cases, 464 controls) were enrolled. Notably, among cases, 10 (16.7%) were students, 3 (5.0%) had a history of syphilis, and 14 (23.3%) had a single sex partner in the past six months. Female sex worker (FSW) status was strongly associated with syphilis (odds ratio [OR] = 3.40; 95% confidence interval [CI] = 1.96-5.90). In multivariable analysis, recent syphilis was associated with inconsistent condom use for vaginal/anal sex among FSWs (adjusted OR [aOR] = 3.42; 95%CI = 0.92-12.70) and among non-FSWs, with younger age (aOR = 0.36; 95%CI = 0.19-0.70; increase per category from 20-24, 25-29 to ≥30 years) and ≤high school education (aOR = 5.24; 95%CI = 1.95-14.10). A notable proportion of cases were those with first time infection and those with only a single partner. Moreover, risk factors differed between FSWs and non-FSWs, and a multi-pronged approach to prevent syphilis is required.

Rubella outbreak among workers in three small- and medium-size business establishments associated with imported genotype 1E rubella virus-Shizuoka, Japan, 2015

On 12 February 2015, a local health department (LHD) in Shizuoka prefecture identified two reported rubella cases in its jurisdiction as employees of the same company. As other employees at the company resided both inside and outside of the health department's jurisdiction, it began collaborating with two additional LHDs and the National Institute of Infectious Diseases to investigate and respond to the outbreak, which subsequently identified cases in two additional companies. We obtained epidemiological, clinical, and outbreak response information from the national epidemiological surveillance of infectious disease system's database, the local health departments, and the associated companies. One specimen for genetic sequencing was collected from each of the three companies. The outbreak included a total of twenty-five cases, with seventeen confirmed and eight probable cases from three companies. Among them, 24 (96%) were male, 22 (88%) were employees of one company (Company X), and none had rubella vaccination history. The median age was 45 years (interquartile range: 40-51). Epidemiological information did not reveal the source of infection nor transmission route. All rubella viruses sequenced from the three specimens were classified into genotype 1E. The nucleotide sequences in the 739 bp-window region were completely identical in two specimens, with only one nucleotide difference in the third specimen. According to phylogenetic analysis, these strains were closely related to the Southeast and East Asian lineage. This rubella outbreak at three companies, ranging in size from small- to medium-size, in Japan occurred among unvaccinated employees aged at least 30 years, most of whom were male. Virologic analyses suggest all cases were infected with the same viral strain imported from Southeast Asia. Similar to these companies, most employees at small- and medium-size businesses in Japan are males with no vaccination history for rubella, which poses a serious risk for associated cases of congenital rubella syndrome (CRS).

A shigellosis outbreak associated with a sports festival at a kindergarten in Kitakyushu City, Japan

INTRODUCTION

Shigellosis cases have decreased gradually in Japan in recent years, but indigenous shigellosis outbreaks sometimes occur in childcare facilities. From national surveillance data, we identified a shigellosis outbreak involving a kindergarten.

METHODS

After detecting Shigella sonnei in Kitakyushu City, we conducted active case finding and epidemiological investigation in Kindergarten Z, including stool specimen collection and interviews. The stool specimens were cultured, and isolated strains were subjected to pulsed-field gel electrophoresis (PFGE) and multiple-locus variable-number tandem-repeat analysis (MLVA).

RESULTS

Between September 1 and December 31, 2014, we identified 19 cases: 14 confirmed, 2 suspected, and 3 asymptomatic. Of the 19 cases, 16 were epidemiologically associated with Kindergarten Z (10 pupils, 5 family members, and 1 teacher). On October 19, a pupil with gastrointestinal illness participated in the kindergarten's sports festival, in which the pupils were split into "red" and "white" teams; the pupil in question belonged to the red team. Attack rates of the red and white teams were 8% (7/82) and 0% (0/108), respectively (relative risk, 10.5; 95% confidence interval, 1.3-82.1). PFGE patterns were identical or similar for the isolates in all 17 cases; 7 isolates were identical, and the others had one locus difference on MLVA.

CONCLUSIONS

We concluded that contact during the sports festival could have been responsible for spread of the shigellosis outbreak at the kindergarten, although the infection source was not determined. It is vital to inform guardians immediately after detection of shigellosis cases that symptomatic pupils should not participate in activities such as sports festivals.

Severe Acute Respiratory Syndrome Coronavirus 2 Infection among Returnees to Japan from Wuhan, China, 2020

In early 2020, Japan repatriated 566 nationals from China. Universal laboratory testing and 14-day monitoring of returnees detected 12 cases of severe acute respiratory syndrome coronavirus 2 infection; initial screening results were negative for 5. Common outcomes were remaining asymptomatic (n = 4) and pneumonia (n = 6). Overall, screening performed poorly.

Epidemiology of a workplace measles outbreak dominated by modified measles cases at Kansai international airport, Japan, during august-september 2016

OBJECTIVES

In August 2016, a measles outbreak at Kansai International Airport was the first workplace measles outbreak since Japan was verified as having achieved measles-elimination status in March 2015. We investigated this outbreak with a focus on evaluating the ability of vaccinated individuals to transmit measles virus (MV).

METHODS

We considered a case of laboratory-confirmed measles with onset between August 9 and September 29, 2016, among workers of Kansai International Airport. History of vaccination status with measles-containing vaccine (MCV) was confirmed by reviewing records. The potential sources of each MV infection were assessed by interviewing each infected worker about the clinical course of their infection and their behavioral history.

RESULTS

Of 30 affected ground crews identified, 16 (53%) were vaccinated with ≥ 1 dose of MCV, 2 (7%) were unvaccinated, and 12 (40%) had an unknown vaccination status. The index case, a patient with classical measles with unknown vaccination status, presumably transmitted MV to all the subsequent 29 cases. The majority of patients (23, 77%; 15 vaccinated, 8 in unknown vaccination status) were diagnosed with modified measles due to mild illness. Modified measles were characterized clinically by signs of catarrh (4/23, 17%) in a few cases, with a median incubation period of 16 (range, 11-21) days. No onward transmission from vaccinated cases was suggested. An overseas traveler who visited the airport with measles symptoms was identified as the possible primary source of this outbreak.

CONCLUSIONS

The low MV transmission ability of vaccinated individuals was reaffirmed. Contact tracing of vaccinated modified measles cases can be limited to a person at high risk of infection (e.g., households, person with immunosuppression). To maintain measles-elimination status, completing two doses of MCV should be ensured, especially for international travelers and for those who are frequently exposed to these travelers, such as airport workers.

SARS-CoV-2 Genome Analysis of Japanese Travelers in Nile River Cruise

Japan has reported 26 cases of coronavirus disease 2019 (COVID-19) linked to cruise tours on the River Nile in Egypt between March 5 and 15, 2020. Here, we characterized the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genome of isolates from 10 travelers who returned from Egypt and from patients possibly associated with these travelers. We performed haplotype network analysis of SARS-CoV-2 isolates using genome-wide single-nucleotide variations. Our analysis identified two potential Egypt-related clusters from these imported cases, and these clusters were related to globally detected viruses in different countries.

SAT0124 RISK OF SERIOUS INFECTION, MALIGNANCY, OR DEATH IN JAPANESE RHEUMATOID ARTHRITIS PATIENTS TREATED WITH A COMBINATION OF ABATACEPT AND TACROLIMUS: A RETROSPECTIVE COHORT STUDY

Background:

Both Abatacept (ABT) and Tacrolimus (Tac) suppress T cell immunity, but it is unknown whether combinations of these will increase the risk of adverse events.

Objectives:

To evaluate whether combining ABT and Tac increases the risk of infection and malignancy compared to their individual use in Japanese rheumatoid arthritis (RA) patients.

Methods:

We conducted a retrospective cohort study of RA patients using the multicenter database in Japan (NinJa). The dataset was clinical information at a certain point within each year, and the point was any point selected by a registered physician. RA was clinically diagnosed in the dataset. (1)

We analyzed the data from RA patients registered in NinJa during the period from April 2010 to March 2019. In this study, we compared three groups who received Tac, ABT or a combination of both. We included patients who had just begun initiating treatment with ABT or Tac, and we excluded patients who used TNF inhibitors, IL-6 inhibitors, and Jak inhibitors in the first year. The primary outcome was defined the composite events including infections that require hospitalization, newly diagnosed malignancy, and death from any cause after initiation of ABT or Tac. We assessed whether the combination contributed to increase the risk of outcome by performing a Cox regression analysis.

Results:

Among the 27032 RA patients in the registry, 2009 patients were included. The Tac, ABT and combination groups consisted of 1328, 563 and 118 patients, respectively. (Figure 1) (Table 1) Primary outcomes occurred in 149 (13.4%), 62 (13.5%), 14 (13.9%) patients, of the Tac, ABT and combination groups, respectively. The incidence between groups was not significantly different (p= 0.638). (Figure 2) A Cox regression analysis was adjusted for the following parameters: age, sex, disease duration, modified health assessment questionnaire, disease activity score 28-CRP, CRP, use of prednisolone, and use of methotrexate. The analysis revealed no significant differences between groups. The hazard ratio (95% confidence interval) was as follows: Tac 1.00 (Ref), ABT 1.02 (0.74-1.40), and combination 1.15 (0.65-2.05).

Table 1.

baseline characteristics

TacrolimusAbataceptCombinationp valueN (person-year)1328 (2505)563 (944)118 (193)age (median [IQR])69.00 [60.00, 76.00]70.00 [61.00, 76.00]67.00 [59.00, 74.00]0.169*sex female (%)1038 (78.2)468 (83.1)97 (82.2)0.039†disease duration (yr) (median [IQR])9.00 [4.00, 18.00]11.00 [5.00, 21.00]11.00 [7.00, 20.00]0.002*Steinbrocker stage (%)I285 (23.5)82 (15.6)12 (12.1)<0.001†II361 (29.8)125 (23.8)25 (25.3)III232 (19.1)150 (28.5)31 (31.3)IV334 (27.6)169 (32.1)31 (31.3)mHAQ (median [IQR])0.25 [0.00, 0.75]0.38 [0.00, 1.00]0.50 [0.00, 1.13]<0.001*DAS28CRP (median [IQR])2.58 [1.88, 3.40]2.77 [2.09, 3.62]3.01 [2.27, 3.98]<0.001*CRP (mg/dL) (median [IQR])0.30 [0.10, 1.02]0.35 [0.13, 1.10]0.30 [0.14, 0.82]0.590*RF positivity (%)708/895 (79.1)331/400 (82.8)57/71 (80.3)0.314†Tacrolimus (mg/d) (median [IQR])1.50 [1.00, 2.00]0.00 [0.00, 0.00]2.00 [1.00, 2.50]<0.001*MTX use (%)619 (46.6)264 (46.9)32 (27.1)<0.001†PSL use (%)749 (56.4)299 (53.1)71 (60.2)0.253†

Abbreviations: anti-CCP, anti-cyclic citrullinated peptide; mHAQ, modified Health Assessment Questionnaire; MTX, methotrexate; PSL, prednisolone; RF, rheumatoid factor * Kruskal-Wallis test; † chi square test; ‡ analysis of variance (ANOVA)

Conclusion:

The combination of ABT and Tac does not increase the risk of adverse events in patients with rheumatoid arthritis in Japan when compared to the use ABT or Tac alone. Further evaluation is needed.

References:

[1]Matsui T, et al. Ann Rheum Dis 2007;66:1221–6.

Disclosure of Interests:

Kenichiro Tokunaga: None declared, Kunihiko Matsui: None declared, Hideto Oshikawa: None declared, Toshihiro Matsui Paid instructor for: Chugai Pharmaceutical Co., LTD., Janssen Pharmaceutical K,K,, Shigeto Tohma: None declared

Human psittacosis in Japan: notification trends and differences in infection source and age distribution by gender, 2007 to 2016

PURPOSE

Psittacosis is a bacterial zoonosis caused by Chlamydia (Chlamydophila) psittaci that infects birds. Although potentially fatal, infections can be reduced by controlling the source of infection. We therefore described the epidemiology of psittacosis, focusing on the infection source.

METHODS

We descriptively analyzed psittacosis cases reported through national surveillance in Japan from 2007 to 2016. We also analyzed Chlamydia psittaci prevalence among captive psittaciformes during the same period.

RESULTS

One hundred eleven cases were reported, and the annual number and notification rate of psittacosis declined. While 58% were male and the median age was 61 years, the median age differed by gender (males: 63 years, females: 53 years), with more female cases in those aged <50 years. In addition, the most common infection source differed by gender (men: columbiformes; women: psittaciformes). The decline in notifications was associated with a decline in psittaciformes-associated cases, with a concomitant decline in female cases. The prevalence of C. psittaci among captive psittaciformes also decreased over the period.

CONCLUSIONS

We found important differences in the epidemiology of psittacosis by gender, and the recent decrease in notifications correlated with decreasing C. psittaci prevalence in birds. Risk communications for psittacosis should consider the current epidemiology regarding gender, age, and infection source.

Risk of Seasonal Influenza by Occupation in a Railway Company in a Metropolitan Area of Japan during Three Influenza Seasons

Station staff may be at high risk for influenza due to high frequency contact with other people. We examined the risk of influenza by occupational group in a railway company. A retrospective observational study was conducted among employees at a branch office of a railway company in eastern Japan, located in a metropolitan area, for 2012/13, 2013/14, and 2014/15 influenza seasons. The study population included employees who had received influenza vaccination for the season in question and the previous season. Outcome was defined as self-reported influenza illness during the respective season, identified through the vaccine screening questionnaire in the following season. Study participants included employees whose outcome information could be obtained. Standardized morbidity ratios (SMRs) by occupational group (station staff, engineers, train crew) for each season were calculated. For 2012/13, 2013/14, and 2014/15 seasons, attack rates were 4.7% (19/403), 5.2% (21/407), and 7.8% (31/397), respectively. Among the participants, SMRs of station staff were lower in the 2012/13 (SMR = 57; 95% confidence intervals [CI] = 18-133) and 2014/15 (SMR = 75; 95%CI = 36-138) seasons and similar to other groups in the 2013/14 season. Enhanced countermeasures, regardless of occupational group, may be effective in preventing the spread of influenza infection.

Sociodemographic characteristics and clinical description of congenital syphilis patients and their mothers in Japan: a qualitative study, 2016

Background In Japan, congenital syphilis (CS) notifications have increased recently. However, little is known about the CS cases or the clinical and sociodemographic characteristics of the patients' mothers.

METHODS

Twelve cases of CS were reported through national surveillance in the period March-December 2016, and the mothers of seven patients were included in this study. The patients' mothers and physicians completed a self-administered questionnaire, providing sociodemographic and clinical information of the patients and their mothers. In addition, we explored the awareness and knowledge of, attitudes towards and practices regarding CS occurrence through semistructured interviews with the mothers.

RESULTS

Of the seven CS patients, three were asymptomatic, with a range of non-specific clinical manifestations in the rest. The mothers tended to be of young age, unmarried and to have a history of commercial sex work, other sexually transmissible infections (STIs) and no or irregular prenatal care visits during pregnancy. Of the four mothers who had had regular prenatal care visits, two had tested negative for syphilis at the first trimester antenatal screening. Themes emerged that indicated challenges in preventing CS, including a lack of guidance or guidelines for physicians to consider testing for syphilis after the first trimester, lack of physicians' awareness or experience of syphilis or CS and a lack of awareness or knowledge in pregnant women regarding STIs.

CONCLUSIONS

Key characteristics of recent CS patients and their mothers in Japan were revealed, identifying previously reported factors as well as new challenges. A holistic approach, designed to address challenges at the level of the healthcare system, healthcare provider and the pregnant woman and her partner will be important in preventing CS.

Randomized clinical trial of extensive intraoperative peritoneal lavage versus standard treatment for resectable advanced gastric cancer (CCOG 1102 trial)

BACKGROUND

A survival benefit of extensive intraoperative peritoneal lavage (EIPL) has been reported in patients with gastric cancer with positive peritoneal cytology. The hypothesis of this study was that EIPL may reduce peritoneal recurrence in patients with advanced gastric cancer who undergo surgery with curative intent.

METHODS

This was an open-label, multi-institutional, randomized, phase 3 trial to assess the effects of EIPL versus standard treatment after curative gastrectomy for resectable gastric cancer of T3 status or above. The primary endpoint was disease-free survival (DFS); secondary endpoints were overall survival, peritoneal recurrence-free survival and incidence of adverse events.

RESULTS

Between July 2011 and January 2014, 314 patients were enrolled from 15 institutions and 295 patients were analysed (145 and 150 in the EIPL and no-EIPL groups respectively). The 3-year DFS rate was 63·9 (95 per cent c.i. 55·5 to 71·2) per cent in the EIPL group and 59·7 (51·3 to 67·1) per cent in the control group (hazard ratio (HR) 0·81, 95 per cent c.i. 0·57 to 1·16; P = 0·249). The 3-year overall survival rate was 75·0 (67·1 to 81·3) per cent in the EIPL group and 73·7 (65·9 to 80·1) per cent in the control group (HR 0·91, 0·60 to 1·37; P = 0·634). Peritoneal recurrence-free survival was not significantly different between the two groups (HR 0·92, 0·62 to 1·36; P = 0·676). No intraoperative complications related to EIPL were observed.

CONCLUSION

EIPL did not improve survival or peritoneal recurrence in patients who underwent gastrectomy for advanced gastric cancer. Registration number: 000005907 (http://www.umin.ac.jp/ctr/index.htm).

Correlates of laboratory-confirmed measles in Japan, 2011-2015

BACKGROUND

With the progressive decline in the incidence of measles in Japan, its diagnosis has become challenging, with fewer physicians having experience in examining measles patients. We aimed to determine the correlates of laboratory-confirmed measles to help physicians improve their measles diagnosis.

METHODS

This study was conducted using the National Epidemiological Surveillance of Infectious Disease (NESID) system data during 2011-2015. Among clinically suspected measles patients reported to NESID, measles virus (MV)-positive patients were compared with MV-negative patients. The odds ratios (OR) and associated 95% confidence intervals (CI) were determined using logistic regression.

RESULTS

A total of 4168 laboratory-tested patients were notified to NESID. We analysed 618 MV-positive patients (median age, 17 years; interquartile range [IQR], 4-30 years) and 600 MV-negative (median age, 10 years; IQR, 1-29 years) patients after excluding those that met the exclusion criteria or were reported during the rubella epidemic period (the 18th epidemiological week of 2012 to the 46th week of 2013). Having an epidemiological link with a measles patient within 14 days of onset (OR, 14.9; 95% CI, 10.0-23.3), a history of recent international travel (OR, 11.7; 95% CI, 6.9-19.9), and unvaccinated/unknown vaccination status for measles-containing vaccine (MCV; OR, 3.7; 95% CI, 2.3-5.7) were significantly associated with MV-positive status. International travel (adjusted OR, 10.2; 95% CI, 5.9-17.7) and unvaccinated/unknown MCV vaccination status (adjusted OR, 5.8; 95% CI, 3.5-9.8) remained significantly associated with MV-positive status after adjusting for age, sex, and each other.

CONCLUSION

In low-incidence Japan, having an epidemiological link, international travel, and lack of MCV vaccination were correlates of laboratory-confirmed measles. The findings of this study could potentially improve the clinical diagnosis of measles, which can lead to more efficient testing and earlier laboratory confirmation.

1201. A Prolonged Multispecies Outbreak of Carbapenemase-Producing Enterobacteriaceae Due to Transmissible Plasmid With Carbapenemase Gene

Background

In 2010, a multispecies outbreak of IMP type carbapenemase-producing Enterobacteriaceae (IMP-CPE) occurred at a large acute care hospital in Japan. The outbreak continued for years involving more than 100 patients mainly in surgical wards.

Methods

Because of the long period of the outbreak, investigation were focused on hospitalized patients whose clinical samples were positive for IMP-CPE between July 2013 and March 2014. A case–control study was conducted for cases who underwent abdominal surgery with controls from whom meropenem-susceptible Enterobacteriaceae were isolated. Pulsed-field gel electrophoresis (PFGE) was used for molecular typing. To evaluate genetic relationship among IMP-CPE isolates of different species, plasmid analysis using S1 nuclease to separate plasmid and chromosomal DNA followed by plasmid DNA extraction and whole-genome sequencing (WGS) was conducted.

Results

During the study period, 22 cases were identified and 22 IMP-CPE isolates which consisted of eight Escherichia coli, five Klebsiella oxytoca, five Enterobacter cloacae, three Klebsiella pneumoniae and one Enterobacter aerogenes were obtained. All five isolates of K. oxytoca had similar PFGE profiles which suggested clonal transmission. However, PFGE profiles of E. coli, E. cloacae and K. pneumoniae isolates were diverse. Plasmid analysis revealed that all 22 isolates shared ca. 50 kb IncN plasmid with bla_IMP-6 which implies interspecies transmission of it The case–control study which adjusted by days of hospitalization with 11 cases and 24 controls revealed that pancreato-duodenectomy (adjusted odds ratio (aOR) = 6.4, 95% confidence interval (CI) 1.3–32.4) and enteric fistula (aOR = 8.0, 95% CI 1.5–41.9) were associated with IMP-CPE acquisition. Use of endoscopy within the past six months was not associated with IMP-CPE (aOR = 0.8 95% CI 0.2–4.2). With a bundled infection control with Osaka City Public Health Office, the outbreak was contained in July 2016.

Conclusion

Dissemination of carbapenemase gene by transmissible plasmid can play a critical role to complicate epidemiology of CPE outbreak and made it difficult to control. Plasmid analysis using WGS technology is a promising tool to untangle it.

Disclosures

All authors: No reported disclosures.

673. Syphilis Outbreak in Women Who Have Sex with Men in Japan: A Case–Control Study in Tokyo, 2017–2018

Background

In Japan, syphilis notifications have increased sharply, with Tokyo accounting for a third of all cases. Importantly, the increase in women has been remarkable, with the majority being women who have sex with men. We therefore conducted a prospective case–control study to evaluate correlates of recent syphilis infection among women in Tokyo.

Methods

We employed a test-negative design case–control study among women who sought a syphilis test at a women’s health clinic in Tokyo, comparing socioeconomic status, medical history, and recent sexual behaviors/partnerships, between those who were diagnosed with recent syphilis infection based on clinical signs and serological test results (cases) vs. those who were nonreactive for the nontreponemal test (controls). Participants aged ≥20 years and sexually active in the past 6 months were recruited from June 2017 to March 2018 and completed a self-administered questionnaire. We described cases and assessed for correlates of recent syphilis infection based on odds ratios (ORs) and 95% confidence intervals (CIs).

Results

A total of 524 women, composed of 60 cases and 464 controls, were enrolled. The median age was 23 years (range = 20–54) among cases and 26 years (range = 20–59) among controls. Of the 60 cases, 10 (17%) were current students and three (5%) had a history of syphilis; in the past 6 months, while 35 (58%) had engaged in commercial exchange of sexual practices, 14 (23%) had only one sex partner. Having lower educational attainment (OR = 4.1; 95% CI = 2.1–8.1), not being employed full-time (OR = 3.1; 95% CI = 1.8–5.5), and commercial exchange of sexual practices (OR = 3.4; 95% CI = 2.0–5.9) were associated with case status in univariate analysis. The association between case status and inconsistent condom use (relative to consistent condom use) during vaginal/anal sex in the past 6 months (OR = 2.0; 95% CI = 0.9–4.3) became stronger when restricted to women engaged in commercial exchange of sexual practices (OR = 4.0; 95% CI = 1.4–10.9).

Conclusion

This was the first study to evaluate potential risk factors for recent syphilis infection among women in Japan. In light of these findings, we may need a multi-pronged approach to prevent and control syphilis, for both those engaged in commercial exchange of sexual practices and the general population.

Disclosures

All authors: No reported disclosures.