A nationwide epidemic of influenza C virus infection in Japan in 2004.
During the period from January to July 2004, a total of 131 influenza C viruses were detected by cell culture or reverse transcription-PCR (RT-PCR) from specimens that were obtained from children with acute respiratory symptoms in 10 prefectures across Japan. Influenza C virus was identified most frequently in the Miyagi (1.4%, 45 of 3,226 specimens) and Yamagata (2.5%, 31 of 1,263 specimens) prefectures, and the frequency in this year was the highest since 1990. Phylogenetic analysis of the hemagglutinin esterase gene of the 13 strains isolated in nine prefectures revealed that genetically similar strains belonging to the Kanagawa/1/76-related lineage dominantly spread throughout Japan. During the 2004 influenza season, influenza C virus coexisted with epidemics of influenza A virus (H3 strain), and 12 cases were identified from patients who had been diagnosed with influenza-like illness (7 were detected by RT-PCR, and 5 were detected by culture). A comparison of specimens that were found positive by culture with those found positive only by RT-PCR shows that the amount of virus in PCR-positive specimens tended to be lower than in isolation-positive specimens. Although the mean peak temperature in patients in the PCR-positive group was slightly lower, there were no significant differences in characteristics between specimens (i.e., kind of specimen, period from onset to specimen collection, age distribution of patients, and severity of illness). These results suggest that an epidemic of influenza C virus occurred on a national scale during this period and that RT-PCR can be an effective supplemental tool for the evaluation of clinical and epidemiological information.
Matsuzaki
Yoko
Y
Department of Infectious Diseases, Yamagata University School of Medicine, Iida-Nishi 2-2-2, Yamagata 990-9585, Japan. matuzaki@med.id.yamagata-u.ac.jp
Abiko
Chieko
C
Mizuta
Katsumi
K
Sugawara
Kanetsu
K
Takashita
Emi
E
Muraki
Yasushi
Y
Suzuki
Hiroshi
H
Mikawa
Masahide
M
Shimada
Shinichi
S
Sato
Katsuhiko
K
Kuzuya
Mitsutaka
M
Takao
Shinichi
S
Wakatsuki
Kiyoko
K
Itagaki
Tsutomu
T
Hongo
Seiji
S
Nishimura
Hidekazu
H
D000818:Animals; D002642:Chick Embryo; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D006389:Hemagglutinins, Viral / Q000235:genetics; D006801:Humans; D007223:Infant; D007251:Influenza, Human / Q000175:diagnosis / Q000453:epidemiology* / Q000821:virology; D009982:Gammainfluenzavirus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D007564:Japan / Q000453:epidemiology; D008969:Molecular Sequence Data; D010802:Phylogeny; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012621:Seasons; D017422:Sequence Analysis, DNA; D014760:Viral Fusion Proteins / Q000235:genetics; D014776:Virus Cultivation
D006389:Hemagglutinins, Viral; D014760:Viral Fusion Proteins; C060814:hemagglutinin esterase