Jpn. J. Infect. Dis., 52, 1999

Laboratory and Epidemiology Communications

Surveillance of Poliovirus-isolates in Japan, 1998

Tetsuo Yoneyama*, Harumi Sawada1, Hiromasa Sekine2, Akira Sasagawa 3, Yoshitaka Futohashi4, Nakao Sakurai5, Yoko Yokota6, Tohru Ishizaki7, Yoshiaki Karoji8, Mamoru Nakano9, Kazuhito Kajiwara10, Akio Hagiwara and Tatsuo Miyamura

Department of Virology II, National Institute of Infectious Diseases, Musashimurayama 208-0011,
1Hokkaido Institute of Public Health, Sapporo 011-0819, 2Tokyo Metropolitan Research Laboratory
of Public Health, Tokyo 169-0073, 3Niigata Prefectural Research Laboratory for Health and 
Environment, Niigata 950-2144, 4Nagoya City Health Research Institute, Nagoya 467-8615,
5Institute of Public Health, Mie Prefectural Science and Technology Promotion Center, Tsu 514-0003,
6Shiga Prefectural Institute of Public Health and Environmental Science, Otsu 520-0834,
7Kyoto Prefectural Institute of Hygienic and Environmental Sciences, Kyoto 612-8369,
8Kyoto City Institute of Health and Environmental Sciences, Kyoto 604-8845, 9Nara Prefectural 
Institute of Public Health, Nara 630-8131, and 10Fukuoka City Institute of Public Health, Fukuoka 810-0065

Communicated by Tatsuo Miyamura

(Accepted February 10, 1999)

     One of the basic activities of poliomyelitis-surveillance in Japan consists of 
co-operational laboratory diagnosis carried out between the National Institute of 
Infectious Diseases (NIID) and prefectual and municipal public health institutes. 
Every year since 1981, an average of 10 polioviruses have been isolated from clinical 
specimens of paralytic and non-paralytic patients in these local institutions and sent to
NIID for confirmation and intratypic differentiation. Also, on average one case of polio-
myelitis associated with oral poliovirus-vaccine (OPV) has been reported. In 1993, our 
surveillance system highlighted the detection of an imported wild poliovirus in a non-
paralytic patient (1). It is very important to analyze the isolated polioviruses by intratypic
differentiation in order to maintain a reliable surveillance system of poliomyelitis.
     In 1998, 36 poliovirus isolates from 16 clinical patients and 15 healthy children were 
isolated in seven prefectures and three cities. They were sent to NIID and subjected to 
intratypic differentiation by a PCR-restriction fragment length polymorphism method
developed by Dr. Radu Crainic (2). As shown in Table I, all of the examined polioviruses 
were vaccine-derived strains. Details of the isolation and patient information of acute 
flaccid paralysis (AFP) are summarized in Table II. Type 1 vaccine-derived strain was
isolated in Hokkaido from a male, 36-year-old poliomyelitis-patient.  His vaccination 
history is not known. Because he has a healthy daughter who received OPV 14 days 
before the onset of his paralysis, it is thus possible that he was contact-infected with 
the vaccine-virus from his daughter.
     Polioviruses were also isolated from 14 healthy children during activities carried out 
under the surveillance of vaccine-preventable diseases in 1998. Since specimens of healthy
children were collected not less than 2 months after routine vaccination with OPV, very few
polioviruses were isolated during these activities. It is generally considered that there is 
no wild poliovirus circulating in Japan (3). It seems unlikely that the examined number of
polioviruses from AFP cases increased particularly after the notification of certificate for
polio-eradication from the Japanese Ministry of Health and Welfare in March 1998. With 
the improved AFP surveillance activity in Japan started in 1999, the prompt examination of
the isolated enteroviruses from AFP cases will become more important.

REFERENCES
1. Yoneyama, T., Fujiwara, T., Yokota, Y., Takemika, Y. and Hagiwara, A. (1995): 
    Characterization of a wild poliovirus type 3 isolated Japan in 1993. 
    Jpn. J. Med. Sci. Biol.,48, 61-70.
2. Balanant, J., Guillot, S., Candrea, A., Delpeyroux, F. and Crainic, R. (1991): 
    The natural genomic variability of poliovirus analysed by a restriction fragment length
    polymorphism assay. Virology, 184, 645-654.
3. Shimojo, H. (1984): Poliomyelitis control in Japan.  Rev. Infect.Dis., 6, S427-430.


*Corresponding author:  E-mail: tyoneyam@nih.go.jp, Fax: +81-42-561-4729


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