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◆ Congenital rubella syndrome-as of 12th week in 2014
Note: This paper summarizes the information obtained from infectious disease surveillance, based on the Infectious Diseases Control Law, Japan. The contents may be subject to change, along with the development of the situation.
Congenital rubella syndrome (CRS), characterized by the classic triad of cataract, congenital heart disease, and hearing impairment, can occur in the developing fetus of a pregnant woman infected with the rubella virus during the first 20 weeks of gestation.
The number of reported CRS cases remained at 0-2 cases per year from 2005 to 2011 in Japan. However, the annual number of reported cases increased to four cases in 2012, 32 cases in 2013 and in 2014, 8 cases have been reported as of March 26 (12th week of 2014). In this report, we focus on the 44 cases from 2012 to week 12 of 2014. Prefectures reporting the largest number of cases were Tokyo (n=16), Osaka (n=6), Saitama (n=4), Kanagawa (n=3) and Hyogo (n=3) prefectures. Among the 44 cases, 24 were male and 20 female. Of the 44 mothers whose infants developed CRS, 15 mothers had not received rubella vaccine, nine had received rubella vaccine, and 20 did not have a record of vaccination history. During gestation, 30 mothers developed rubella, four mothers did not develop rubella, and 10 mothers did not have any records; of these 30 mothers who developed rubella during gestation, 15 had records of the time of onset, with a median of 9 weeks (range: 3-18).
Diagnosis of CRS was confirmed with detection of rubella-specific IgM antibody (n=25), detection of rubella virus RNA by polymerase chain reaction (PCR) (n=7), or by both methods (n=12). Among the 39 cases that presented with cataract, congenital heart disease and/or hearing impairment (the classic triad), one case had complications of all three, three cases had complication of congenital heart disease and hearing impairment, another three had cataract, 20 had congenital heart disease, and 12 had hearing impairment. Other clinical manifestations reported were retinopathy (n=3), purpura (n=19), splenomegaly (n=9), microcephalus (n=4), mental retardation (n=1), radiolucent bone lesions (n=3), and icterus precox (n=10). Patent ductus arteriosus was the most frequently reported cardiac defect.
From past reports, CRS incidence is known to be correlated with rubella incidence. With regards to the rubella epidemic in Japan that began in 2011, the number of rubella cases peaked during weeks 19 to 22 in 2013 (Figure). There is a lag of 20 to 30 weeks from the time of the pregnant mother’s onset to delivery of an infant with CRS, and in fact, the number of CRS notifications increased during week 43 of 2013 to week 2 of 2014.
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In addition, since there is an estimated 15-30% subclinical infections in rubella, pregnant women may not be aware of their infection. Importantly, since clinical manifestations such as hearing impairment is difficult to detect in the newborn, proactive assessment of CRS is imperative to avoid delay of medical support for the infant. Babies with CRS are considered to be infectious until at least several months after birth, as rubella virus is excreted through nasopharyngeal and urine cultures. Therefore, precautionary measures need to be considered for susceptible individuals in the vicinity of the infant.
Specifically, in order to definitively diagnose CRS, careful examination of infants born from mothers who were infected with rubella virus during early pregnancy is necessary. In addition, careful observation during medical checkups of infants up to 1.5 years of age is the key to early diagnosis of CRS which is also considered to be important for the growth and development of the diagnosed infants. Moving forward, there is a need to deepen discussions and action plans on how to provide better support for the diagnosed infants. Additionally, vaccination of women planning for pregnancy and provision of information and education to their partners regarding rubella is essential in the prevention of CRS. For Japan to achieve rubella elimination by 2020, prevention and response activities must be comprehensively strengthened.
Infectious Disease Surveillance Center,
National Institute of Infectious Diseases
Hiroaki Ito, Kazutoshi Nakashima, Takuya Yamagishi, Yuichiro Yahata,
Tamano Matsui,Hiroshi Satoh, Satoru Arai, Hideo Okuno, Keiko Tanaka-Taya,
Kazuhiko Kanou, Hitomi Kinoshita,Takehito Saito, Takuri Takahashi, Yuzo Arima,
Tomimasa Sunagawa, Kazunori Oishi
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