A trend of Influenza in 1999/2000 season - Gunma , Japan
(IASR 2000; 21: 56-57)

Reported case of influenza to Gunma Prefecture through the National Epidemiological Surveillance of Infectious Diseases started to increase since the 51st week of 1999. Per sentinel case increased 40.97 in the 5th week of 2000. The Gunma Prefectural Institute of Public Health and Environmental Sciences strengthened laboratory services for influenza virus isolation. Following are preliminary results virus isolation.

MDCK cell is employed for virus isolation, and the virus is identified by routine methods. One hundred forty-six specimens from sentinels are examined, and 26 strains are identified as influenza A/H1N1, followed by 19 influenza A/H3N2. The other specimens are not identified yet. Influenza A/H1N1 strains are mostly isolated from children age between 1-9 years old. Whereas, most of influenza A/H3N2 strains are from children under 4 years old. Main symptoms of those isolated cases at the initial consultation include fever to 38C, upper respiratory tract inflammation, muscle and joint pain. Some cases present lower respiratory tract inflammation, convulsion, and paralysis, also.

A 72 years old man presented one of the most characteristic cases. He developed fever, muscle pain, and dehydration, and he was hospitalized. Blood chemistry upon admission revealed WBC 12,400/uL, CRP 15.8mg/dL, GOT 376IU/L, GPT 153IU/L, LDH 1,426IU/L, CPK 17,550IU/L, BUN 121mg/dL, and creatinine 1.7mg/dL. Urine myoglobine elevated greater than 3ug/mL. Remarkable increase of muscle-derived enzyme and musclar paralysis suggested rhabdomyolysis. Symptoms improved by the Day 10. Influenza A/H3N2 was isolated from his gargling fluid. Although it is rare, influenza A may accompany musclar complications such as rhabdomyolysis (JAMA, 1980; Vol.243, No.5, p.461-2). Further virological investigation has been carried out against other influenza cases with similar symptoms.

Virological investigation has been conducted for 19 outbreak incidences at school and social welfare facilities. Influenza A/H1N1 was isolated from 9 incidences at kindergarten and primary school. Influenza A/H3N2 was isolated from 2 incidences at junior high school and social welfare facility. Situations of daily virus isolation from sentinels and outbreak sites are summarized in Figure 1.

Results of susceptibility against influenza vaccine strains among local population was investigated at the pre-epidemic season of 1998 (Figure 2). Low antibody acquisition rate (1:40 or less) against influenza A/H1N1 and B in the all age groups. Influenza trends should be carefully observed hereafter.

Reported by Masae Ohbuchi, Hirokazu Kimura, Yusaku Nakamura, Masayuki Akami, Masuo Inoue, and Kunio Otsuki, Gunma Prefectural Institute of Public Health and Environmental Sciences; Yasuko Nakamura, 1st Dept. of Internal Medicine, Maebashi Red Cross Hospital; Toshiyuki Fukazawa, Dept. of Pediatrics, Maebashi Red Cross Hospital.

Correspondence: Hirokazu Kimura;
E-mail: kimura-hi@pref.gunma.jp

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