A tuberculosis outbreak in a psychiatric hospital: Kanagawa, Japan, 2012

Abstract

In January 2012, an inpatient in a ward of a psychiatric hospital with nearly 300 beds in Kanagawa, Japan, was diagnosed with sputum smear-positive pulmonary tuberculosis (TB). Here we characterise the TB outbreak cases and identify the population at risk. TB was diagnosed when a person tested bacteriologically positive for TB or was determined to have TB by a physician. A latent TB infection (LTBI) case was defined as a person tested positive by interferon-gamma release assay (IGRA). A total of 125 contacts were screened via IGRA and chest X-ray. In all, 15 TB and 15 LTBI cases were found by the end of October 2012, and thereafter no additional TB case was found. Of the 15 TB cases, eight were culture-positive and all the isolates had identical variable number tandem repeat patterns. Twenty-four of the 56 (42.9%, 95% confidence interval (CI) 29.7–56.8) inpatients in the ward had either TB or LTBI with a relative risk of 8.6 (95% CI 1.2–59.3), compared to the staff members who did not work full-time in the ward (one of 20 (5.0%, 95% CI 0.0–24.9)). We recommend that psychiatric hospitals conduct periodic screening of staff members and inpatients for TB to prevent nosocomial TB outbreaks.

Transmission risks of respiratory infectious diseases in various confined spaces: A meta-analysis for future pandemics

“…Due to the multiple sub-compartments (ward, inpatient unit, outpatient department, emergency room, etc. ), various scales of hospitals (primary, secondary, and tertiary), and variability in the number of visiting patients, we made this decision based on the information from a number of included articles; 30 to 77 healthcare workers ( Control and Prevention, 2004a , Control and Prevention, 2004b ; Medrano et al, 2014 ) and 11 to 99 patients ( Beck-Sagué et al, 1992 ; Biribawa et al, 2020 ; Dooley et al, 1992 ; Pan et al, 2016 ; Tasaka et al, 2020 ) in a single ward; 1 to 5 patients in a single patient room ( Leckerman et al, 2010 ), and 100 to 200 patients in a single emergency room ( Cho et al, 2016 ). School or workplace was regarded to have the third-largest number of persons in space: A typical school classroom is occupied by 16–35 students ( Muennig and Woolf, 2007 ; Skarlatos and Manatakis, 2003 ).…”

Analysis of 605 tuberculosis outbreaks in Japan, 1993–2015: time, place and transmission site

“…urban prefectures) were the regular top three prefectures for years [ 1 ]. The psychiatric hospitals involved in the outbreaks had more cases of TB disease than the workplaces in general, probably because in psychiatric hospitals in Japan, the patient's mental rather than physical condition is concentrated on and the delays of TB diagnosis tend to be longer [ 2 , 17 ]. Another reason is that most psychiatric hospitals accommodate long-term inpatients and once a patient develops smear-positive TB in a ward other patients, and possibly staff members working in the same ward, may easily be exposed.…”

“…These facilities may also have an environment in which the air exchange rate is low, causing more TB transmission among contacts [ 7 ]. After 2006 when interferon-gamma release assays (IGRAs) [ 18 – 21 ] were introduced in Japan, the average number of TB disease per outbreak reduced significantly because it became easier for the health authorities to specifically determine those who were likely to be infected with TB and they may have been able to prevent them from developing TB disease via prophylaxis [ 17 ]. The introduction of IGRAs may also have resulted in a reduced number of cases of LTBI thereafter; however, it was only visible in the TB outbreaks in schools where most cases of LTBI found were children and young adults.…”

“…Finally, the original data that MHLW disclosed did not clearly mention that the outbreaks were confirmed by molecular epidemiological evidence. However, the restriction fragment length polymorphism (RFLP) technique became available in Japan around 1995 and analysis of variable numbers tandem repeats (VNTR) became available around 2005 [ 28 – 32 ], so the authors believe that most outbreaks, particularly after 2000, were validated with the use of molecular epidemiology, exemplified by the TB outbreak reports [ 2 , 4 , 6 , 8 – 10 , 17 ].…”

Epidemiology of tuberculosis in foreign students in Japan, 2015–2019: a comparison with the notification rates in their countries of origin

“…The proportion of multidrug-resistant (MDR) TB, which is resistant to the two most potent anti-TB drugs, rifampicin and isoniazid, in previously untreated all types of TB in Japan was 0.4% in 2019; however, for those born in foreign countries the proportion was much higher (2.8%) [2]. TB outbreaks have involved hospitals, workplaces, military training, schools and sometimes homeless persons [7][8][9][10][11][12][13], and an MDR-TB outbreak involving the immigrant population was also reported [14]. Pre-entry screening for TB for immigrants to Japan is expected to be initiated soon [15].…”