Epidemiology and Infection



Surveillance of influenza viruses isolated from travellers at Nagoya International Airport


K. SATO a1, T. MORISHITA a1, E. NOBUSAWA a2, Y. SUZUKI a1, Y. MIYAZAKI a1, Y. FUKUI a3, S. SUZUKI a3 and K. NAKAJIMA a2c1
a1 Department of Microbiology, Aichi Prefectural Institute of Public Health, Nagoya 462-8576, Japan
a2 Department of Virology, Medical School, Nagoya City University, 1 Kawasumi, Mizuhocho, Mizuho-ku, Nagoya 467, Japan
a3 Nagoya International Airport Quarantine Office, Toyoyama-cho, Aichi, 480-01, Japan

Abstract

In order to conduct a survey of influenza viruses entering Japan via travellers arriving by airplanes, gargle solutions were collected from passengers who reported to the quarantine station of Nagoya International Airport complaining of respiratory symptoms. From 504 samples collected between August 1996 and March 1999, 30 influenza virus strains were isolated. Twenty-eight of the isolates were influenza A (H3N2) viruses and two were influenza B viruses. No H1N1 virus was isolated. Among 28 isolates of H3N2 virus, 3 strains were obtained outside the influenza season. Nucleotide sequences of the haemagglutinin (HA) genes of these isolates along with those from domestic patients were analysed in order to determine the influence of imported influenza viruses by travellers on epidemics in Japan. From the phylogenetic and chronological aspects, the possibility was suggested in one case in 1997/8 and two in the 1998/9 season that imported virus by travellers may have influenced the domestic influenza epidemics.

(Accepted February 10 2000)


Correspondence:
c1 Author for correspondence.


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