Age-specific antibody prevalence for influenza C virus in 1997 - Hiroshima
(IASR 2001; 22: 89-90)

Influenza C virus was first isolated in 1947 from a patient with upper respiratory tract infection. Epidemiological knowledge of the virus, however, is limited compared with those of influenza A and B viruses. In order to gain insights into influenza C virus infection in Hiroshima Prefecture, we investigated the antibody acquisition rate among the inhabitants.

Using sera collected from 186 individuals aged 0-84 years living in Hiroshima Prefecture, hemagglutination inhibition (HI) antibody titer was measured against influenza C virus. If a cut-off value was set at 1:10, 74% (134/186) of the sera were positive for HI antibodies, with titers ranging from 1:10 to 1:80. The antibody acquisition rate in every 5-year-old stratification turned out to be high except the 0-4 years age group (Figure). Similar results are reported by Homma et al. [1] and Kaji et al. [2]. According to Homma et al., influenza C virus infection in humans first occurs at early stages of infancy, and the antibody titers are sustained at high levels due to reinfections.

We are keeping on conducting virological surveillance for obtaining further knowledge on this virus [3].

References
1. Homma, M. et al.: Age distribution of the antibody to type C influenza virus. Microbiol. Immunol., 26, 639-642, 1982.
2. Kaji, M. et al.: Distribution of antibodies to influenza C virus. Kurume Med. J., 30, 121-123, 1983.
3. Takao, S. et al.: Isolation of influenza C virus during the 1999/2000-influenza season in Hiroshima Prefecture, Japan. Jpn. J. Infect. Dis., 53, 173-174, 2000.

Reported by: Shinichi Takao, Shinji Fukuda, Yukie Shimazu, Masahiro Noda, and Shizuyo Tokumoto, Division of Microbiology II, Hiroshima Prefectural Institute of Health and Environment.

Correspondence: Shinichi Takao;
E-mail: takao@urban.ne.jp
Fax: +81-82-252-8642

Return to the TopPage

Back to Home