Jpn. J. Infect. Dis., 53 (6), 246-247, 2000

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Laboratory and Epidemiology Communications

Seroepidemiological Survey of Influenza C Virus in Hiroshima Prefecture, Japan

Shinichi Takao*, Akie Toyota1, Yukie Shimazu, Shinji Fukuda, Masahiro Noda and Shizuyo Tokumoto

Division of Microbiology II and 1Division of Physics and Chemistry, Hiroshima@Prefectural Institute of Health and Environment, Minami-machi 1-6-29, Minami-ku, Hiroshima 734-0007

Communicated by Hiroo Inouye

(Accepted January 29, 2001)

Influenza C virus, which was first isolated from a patient with a mild influenza-like illness in 1947 (1), has been considered an etiological agent for respiratory infections in human beings (2). However, the epidemiological information regarding this virus, such as the mechanisms of its transmission and maintenance in nature, have been limited, as compared with those of influenza A and B viruses. We investigated the antibody prevalence of this virus in the residents of Hiroshima Prefecture to elucidate the extent of influenza C virus infection, and in this paper we report the results of the age distribution of antibody against influenza C virus in comparison with those against influenza A and B viruses.

A total of 186 sera, which were collected from residents living in Hiroshima Prefecture in the age range of 0-84 years in 1997, were measured for hemagglutinin-inhibition (HI) antibody titer against influenza A, B, and C viruses. The age-related distribution of HI antibody and the positive rate in age groups against influenza C, A, and B viruses are shown in Figures 1 and 2. Significant levels of HI antibody-positive rate (134/186: 73.6%) against influenza C virus were found in the sera tested, with the titers ranging from 1:10 to 1:80. The pattern of the HI antibody-positive rate in age groups against influenza C virus was markedly different from those of influenza A and B viruses; a high percentage of antibody-positive rate (more than 50%) was shown only in the age groups of 0-14 years against A/Sydney/5/97(H3N2), or in that of 5-24 and 30-39 years against B/Harbin/7/94, while the positive rate against A/Beijing/262/95(H1N1) was generally low in all age groups. In contrast, the antibody-positive rate against C/Hiroshima/290/99 was high in all age groups except for that of 0-4 years. Similar antibody-prevalence patterns in age groups against influenza C virus have also been reported in previous studies (3,4). Thus, we speculate that primary infection by this virus mainly occurs early in life and reinfection plays a role in maintaining the antibody at high levels, as described by Homma (3). We are currently conducting a virological surveillance on the occurrence of this virus to obtain additional epidemiological information (5).

REFERENCES

  1. Taylor, R.M. (1949): Studies on survival of influenza virus between epidemics and antigenic variants of the virus. Am. J. Public Health, 39, 171-178.
  2. Katagiri, S., Ohizumi, A. and Homma, M. (1983): An outbreak of type C influenza in a children's home. J. Infect. Dis., 148, 51-56.
  3. Homma, M., Ohyama, S. and Katagiri, S. (1982): Age distribution of the antibody to type C influenza virus. Micrbiol. Immunol., 26, 639-642.
  4. Dykes, A.C., Cherry, J.D. and Nolan, C.E. (1980): A clinical, epidemiologic, serologic, virologic study of influenza C virus infrction. Arch. Intern. Med., 140, 1295-1298.
  5. Takao, S., Matsuzaki, Y., Shimazu, Y., Fukuda, S., Noda, M. and Tokumoto, S. (2000): Isolation of influenza C virus during the 1999/2000-influenza season in Hiroshima Prefecture, Japan. Jpn. J. Infect. Dis., 53, 173-174.
  6. Maurice, W. H. and Kendal, A.P., (1989): Influenza viruses. p.631-668. In Schmit, N.J. and Emmons, R.W. (eds), Diagnostic Procedures for Viral, Rickettial and Chlamydial Infections. American Public Health Association, Inc., Washington, D.C.

*Corresponding author: Fax: +81-82-252-8642, E-mail: takao@urban.ne.jp

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