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).

2015年2月12日，静冈县地方卫生部门（LHD）将同一地区的两例风疹病例报告为同一公司的雇员。当公司的其他员工居住在卫生部门管辖范围内外时，该公司开始与另外两个LHD和美国国立传染病研究所合作，调查并应对疫情，随后确定了另外两家公司的病例。我们从国家传染病系统数据库的流行病学监测，当地卫生部门以及相关公司那里获得了流行病学，临床和暴发应对信息。从三个公司中的每个公司收集了一个用于基因测序的标本。爆发共包括25例，来自三家公司的17例确诊病例和8例可能病例。其中，24人（96％）为男性，22人（88％）为一家公司（X公司）的员工，没有人感染风疹。中位年龄为45岁（四分位间距：40-51）。流行病学信息没有揭示感染源或传播途径。从这三个标本测序出的所有风疹病毒都被分类为基因型1E。739 bp窗口区域中的核苷酸序列在两个样本中完全相同，而在第三个样本中只有一个核苷酸差异。根据系统发育分析，这些菌株与东南亚和东亚谱系密切相关。这种风疹在三家公司中爆发，规模从中小到大，在日本，年龄至少为30岁的未接种疫苗的员工中，大多数是男性。病毒学分析表明，所有病例均感染了从东南亚进口的相同病毒株。与这些公司类似，日本中小企业的大多数员工都是男性，没有风疹疫苗接种史，这给与先天性风疹综合症（CRS）相关的病例构成了严重的风险。