Multisource surveillance conducted by the Tokyo Metropolitan Government during the Tokyo 2020 Olympic and Paralympic Games

The Tokyo 2020 Olympic and Paralympic Games (the Games) were held from 23 July to 5 September 2021 in Tokyo, Japan, after a 1-year delay due to the coronavirus disease (COVID-19) pandemic. The Tokyo Metropolitan Government was responsible for monitoring and responding to infectious disease outbreaks other than COVID-19 during the Games. A multisource surveillance system was used from 1 July to 12 September 2021 for the early detection and rapid response to infectious diseases. This included routine notifiable disease surveillance, sentinel surveillance, syndromic surveillance, cluster surveillance, ambulance transfer surveillance and the Tokyo Infectious Alert system. Daily reports were disseminated summarizing the data collected from the multisource surveillance system. No case of infectious disease under the Tokyo Metropolitan Government system required a response during the Games. The multisource surveillance was useful for providing intelligence during the Games and, if required, could contribute to the early detection and rapid response to outbreaks during other mass gatherings. The system could be improved to overcome the challenges implied by the findings of this multisource surveillance.

A multidrug-resistant tuberculosis outbreak in a language school: Tokyo, Japan, 2019-2020

Background

Japan has successfully reduced the burden of tuberculosis (TB) in the past seven decades; however, there are still some issues in eliminating TB. Its presence in immigrants, particularly multidrug-resistant (MDR) TB, is one of them. In mid-September 2019, a teenage Chinese male student in a morning class of a Japanese language school in Tokyo, Japan, was diagnosed with sputum smear-positive pulmonary MDR-TB.

Method

The outbreak cases were analyzed in a cohort study.

Results

We investigated 138 students and 18 teachers, of whom 81 (51.9%) were male, 115 (73.7%) were aged from 20 to 29 years, and 124 (76.9%) were from China. Four other students in the same classroom and another in a different classroom from the index patient in the morning classes were also diagnosed with MDR-TB disease by the end of November 2020. In addition, 31 cases of latent TB infection (LTBI) were detected among the students and teachers. Students in the same classroom had the highest risk of TB infection (78.9%, 95% confidence interval [CI]: 54.4%-93.9%) with a relative risk of 8.6 (95% CI: 3.9-19.0), followed by students in the other classrooms of the morning classes (25.9%, 95% CI: 15.0%-39.7%) with a relative risk of 2.8 (95% CI: 1.2-6.8), compared with the afternoon class students (9.2%, 95% CI: 3.5-19.0) who had minimal contact with the index patient.

Conclusion

National TB programs should adopt prophylaxis regimens for MDR-TB LTBI cases and provide prophylaxis to them, particularly if related to an outbreak. The Japanese government should screen immigrants for TB, particularly those from TB-endemic areas.

Positivity of interferon-gamma release assay among foreign-born individuals, Tokyo, Japan, 2015-2017

Background

The aim of this study is to analyze interferon-gamma release assay (IGRA) data of foreign-born individuals in Japan derived from tuberculosis (TB) contact investigations.

Methods

A contact with a TB patient was considered to have occurred when an individual had contact with a TB patient for more than 8 h indoors. This is a retrospective cohort study, and all the TB contacts tested with IGRA during the contact investigations conducted by the Shinjuku city Health Office from 2015 through 2017 were enrolled.

Results

A total of 880 foreign-born contacts were investigated. The IGRA positivity of the contacts from China and Viet Nam were both 5.1% (95% confidence intervals [CIs]: 3.2%-7.8% and 2.4%-9.5%, respectively), whereas that from Nepal and Myanmar were 24.4% (95% CI: 16.0%-34.6%) and 23.3% (95% CI: 9.9%-42.3%), respectively. Multiple logistic regression analysis showed that the risk factors were smear status of the index patient (1+: adjusted odds ratio [aOR]: 6.2, 95% CI: 1.2-30.5, smear status 3+: aOR: 14.3, 95% CI: 1.7-118.2), age of the contact (aOR: 1.1, 95% CI: 1.0-1.1 for 1 year increment), and being born in Nepal (aOR: 5.6, 95% CI: 2.8-11.2) and Myanmar (aOR: 4.3, 95% CI: 1.4-13.0), compared with China as reference.

Conclusions

In contact investigations involving foreign-born individuals, local health offices should carefully consider the composition of the TB contacts and expand the focus of the investigation, if deemed necessary.

Enhancing Preparedness against Rubella at the Workplace: Proactive Prevention Efforts by the Tokyo Metropolitan Government

In the 2012-2013 rubella epidemic in Japan, most transmissions in Tokyo occurred at workplaces, especially among men aged 20-49 years. This tendency was likely related to previous rubella immunization policies that prioritized female adolescents. Since 2015, the Tokyo Metropolitan Government has been promoting a project to prevent rubella and other infectious diseases in workplaces. Companies participate by choosing one or more of three options: (i) acquire fundamental understanding of infectious diseases, (ii) develop a Business Continuity Plan (BCP) for infectious diseases in the workplace, and (iii) increase rubella antibody prevalence in employees.Criteria for accomplishment are (i) at least 80% of employees complete the infectious disease training modules or (ii) produce a BCP and (iii) at least 90% of employees demonstrate the presence of antibodies at levels sufficient for preventing rubella. As of July 2018, 39.8% (n ＝ 90) of the 226 companies that began participating in 2015-2017 had met at least one accomplishment criteria (Option I, 42.7% of 192 companies; Option II, 19.3% of 140; and Option III, 17.0% of 53). The main project challenges were recruiting companies and following participating companies. Although early in its implementation, this project has made considerable contributions toward rubella elimination in Japan.

Shedding of Rubella Virus among Infants with Congenital Rubella Syndrome Born in Tokyo, Japan, 2013-2014

Rubella is usually a mild illness, with febrile rash being its main symptom. However, serious consequences of rubella infection can result when the infection occurs during the early stages of pregnancy. After the occurrence of a rubella outbreak in Japan that was observed from 2012 to 2013, 45 infants were reportedly born with congenital rubella syndrome (CRS). We prospectively followed the 15 CRS cases reported in Tokyo to determine the virus shedding periods by using nested reverse transcriptase-polymerase chain reaction to detect rubella virus genes. Throast swabs were used for virus detection. The virus shedding period was measured from birth until the time when the sample last tested positive followed by 2 consecutive negative samples. Kaplan-Meier method was used to estimate the proportion of cases remaining positive for rubella virus genes over time. The proportion of CRS cases shedding virus dropped steadily after birth, dropping to 33.8% at 6 months and 16.9% at 12 months. Our findings also suggested that the earlier the mother's onset of rubella during pregnancy, the longer the infant remained positive. Based on our findings, we believe that infants with CRS should be monitored for rubella virus shedding until 1 year of age.

Detection of Tuberculosis Infection Hotspots Using Activity Spaces Based Spatial Approach in an Urban Tokyo, from 2003 to 2011

Background

Identifying ongoing tuberculosis infection sites is crucial for breaking chains of transmission in tuberculosis-prevalent urban areas. Previous studies have pointed out that detection of local accumulation of tuberculosis patients based on their residential addresses may be limited by a lack of matching between residences and tuberculosis infection sites. This study aimed to identify possible tuberculosis hotspots using TB genotype clustering statuses and a concept of “activity space”, a place where patients spend most of their waking hours. We further compared the spatial distribution by different residential statuses and describe urban environmental features of the detected hotspots.

Methods

Culture-positive tuberculosis patients notified to Shinjuku city from 2003 to 2011 were enrolled in this case-based cross-sectional study, and their demographic and clinical information, TB genotype clustering statuses, and activity space were collected. Spatial statistics (Global Moran’s I and Getis-Ord Gi* statistics) identified significant hotspots in 152 census tracts, and urban environmental features and tuberculosis patients’ characteristics in these hotspots were assessed.

Results

Of the enrolled 643 culture-positive tuberculosis patients, 416 (64.2%) were general inhabitants, 42 (6.5%) were foreign-born people, and 184 were homeless people (28.6%). The percentage of overall genotype clustering was 43.7%. Genotype-clustered general inhabitants and homeless people formed significant hotspots around a major railway station, whereas the non-clustered general inhabitants formed no hotspots. This suggested the detected hotspots of activity spaces may reflect ongoing tuberculosis transmission sites and were characterized by smaller residential floor size and a higher proportion of non-working households.

Conclusions

Activity space-based spatial analysis suggested possible TB transmission sites around the major railway station and it can assist in further comprehension of TB transmission dynamics in an urban setting in Japan.