Isolation of influenza B virus, January - February 2001 - Kagoshima
(IASR 2001; 22: 61-61)

We report on 2 influenza B virus isolates which demonstrated a low hemagglutination inhibition (HI) titer, 1:10, for B/Yamanashi/166/98.

One isolate was recovered from a 2-year-old boy who complained of fever (39.8C), cough and runny nose and was diagnosed as influenza at a pediatrician in Kagoshima City. Throat swabs yielded the virus on MDCK cells, and its hemagglutination (HA) titer was 1:32 against guinea pig RBCs. The other isolate was collected from a 31-year-old male who complained of fever (38.5C), cough, runny nose and joint pain and was diagnosed as influenza at an internist in Kagoshima City. The isolate demonstrated an HA titer of 1:64 against guinea pig RBCs.

HI tests were carried out using ferret antisera provided by NIID. The 2 isolates showed HI titers of < 1:10 (homo-titer 1:40) for B/Shangdong/07/97 and 1:10 (homo-titer 1:320) for B/Yamanashi/166/98. We identified these isolates as influenza B virus by RT-PCR and a commercially available EIA kit.

According to the epidemiological surveillance of infectious diseases in Kagoshima Prefecture, the number of influenza-like illness remains at 3.66 per sentinel site at week 6, 2001, which is considerably lower than those in the preceding years. As of February 21, a total of 7 influenza A/H3 virus strains were isolated.

Reported by: Naomi Shinkawa, Ken-ichirou Yoshikuni, Tadayuki Arima, Toshiro Honda, Nobuhiro Ueno, Kohji Nagata, Kagoshima Prefectural Institute for Environmental Research and Public Health; Takuya Ikeda, Ikeda Hospital.

Correspondence: Naomi Shinkawa;
E-mail: nao.s@ma3.justnet.ne.jp
Fax: +81-99-224-2614

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