Isolation of adenoviruses from respiratory infections, November - December 2000 - Sendai City and Yamagata City
(IASR 2001; 22:33-34)

The Sendai National Hospital Virus Research Center has been collecting clinical specimens of patients with respiratory diseases from medical facilities in the area. In order to study epidemiology of virus infections, virus isolation has been carried out by inoculation of specimens onto 6 kinds of culture cells (micro-plate methods). In 1999, influenza A (H1N1) virus had been isolated since the beginning of November in Sendai, but none has been isolated during this influenza season (as of December 27, 2000). However, many children presenting influenza-like illness visit pediatricians.

In order to isolate viruses, nasopharyngeal swabs were collected from sick children. Cytopathic effect (CPE) was observed on HEp-2 cells and the human embryonic fibroblasts, which is specific to adenovirus infection. All CPE positive samples showed a positive result by the simplified adenovirus antigen detection kit (Adeno check).

Major symptoms included fever (39-40.5C) lasting 3-5 days and exudative redness of the tonsil, which accompanies pain in some elder children. Some patients presented with runny nose, eye discharge, or diarrhea. Intravenous drip infusion was needed in severe cases. Young children sometimes developed pneumonia.

At pediatric clinic A in Yamagata City, the isolation rate for adenoviruses was 5% (6/126) in October, 21% (29/139) in November, 23% (37/161) in December. An increase of the rate was also observed at pediatric clinic B in Sendai City; 7% (11/149) in October, 8% (16/212) in November, and 18% (51/277) in December. During April to September 2000, the monthly isolation rate of adenoviruses at the clinic A and B was 12 (<10%) and 15 (approximately 7%), respectively.

Virus type was examined by the neutralization method. Of 66 isolates submitted from Yamagata City, 55 (83%) were identified as adenovirus type 3, followed by 5 of type 1, 4 of type 2. Sixty-seven isolates from Sendai City were classified into 30 of type 3, 20 of type 2, 5 of type 5, one of type 6, and 4 were unclassified.

Adenoviruses are often isolated from spring to summer. However, as of the end of 2000, considerable number of febrile illnesses were implicated with adenovirus infections. Similar trend was observed in 1997. The clinic A submitted 70 isolates (18%), which were mainly identified as adenovirus type 3 and 4, during October to December. The clinic B had 15 isolates (11%) in December.

These evidences indicate that considerable rate of febrile illnesses in early winter is related with adenovirus infections. Because patients with adenovirus infection often develop fever >39C, it should be noted that adenovirus infection may get mixed in the surveillance of influenza-like illnesses.

Reported by: Michiko Okamoto, Akira Ohmi, Fumiko Chiba, Chiemi Endo, Youko Ito, Hidekazu Nishimura, Virus Research Center, Sendai National Hospital; Yukio Nagai, Nagai Children's Clinic; Noriko Katsushima, Katsushima Pediatric Clinic.

Correspondence: Hidekazu Nishimura;
E-mail: nisimurh@sendai.hosp.go.jp
Fax: +81-22-293-1173

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