Tohoku J. Exp. Med., 2018 July, 245(3)

Fever Responses Are Enhanced with Advancing Age during Respiratory Syncytial Virus Infection among Children under 24 Months Old

CHIAKI KAWAKAMI,¹ ATSUO SATO,² HIROKO SUMITA,³ ATSUSHI ISOZAKI,⁴ HIROYUKI SHIMIZU,⁵ TAICHI KANETAKA,⁶ KOJI MAEHARA,⁷ KOTA AO,⁸ AKIYOSHI NARIAI,⁹ FUMIHIKO TAKESHITA,¹⁰ RIKA KIZU¹ and MASAAKI MORI¹¹

¹Department of Pediatrics, Yokosuka Kyosai Hospital, Yokosuka, Kanagawa, Japan
²Department of Pediatrics, Children's Center, Yokohama Rosai Hospital, Yokohama, Kanagawa, Japan
³Sumita Kodomo Clinic, Yokohama, Kanagawa, Japan
⁴Department of Pediatrics, Yokohama City Minato Red Cross Hospital, Yokohama, Kanagawa, Japan
⁵Children's Medical Center, Yokohama City University Medical Center, Yokohama, Kanagawa, Japan
⁶Ohisama Kodomo Clinic, Tokyo, Japan
⁷Maehara Pediatric Clinic, Tama, Tokyo, Japan
⁸Department of Pediatrics, Yamato Municipal Hospital, Yamato, Kanagawa, Japan
⁹Department of Pediatrics, Yokohama Minami Kyosai Hospital, Yokohama, Kanagawa, Japan
¹⁰Daiichi Sankyo Co., Ltd., Tokyo, Japan
¹¹Department of Lifetime Clinical Immunology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan

The most important risk factor for severe respiratory syncytial virus (RSV) infection is considered young age due to the immature immune system. The risk at young age is reported greater for RSV than for other respiratory infectious agents. Based on the strong association between young age and severity of RSV infection due to immature immunity, we aimed to assess whether there were any age-related differences in fever responses, as one clinical aspect of the immune response. In our observational study over two seasons (2014-2015 and 2015-2016), daily body temperatures of children under 3 years old with RSV infection were recorded from the first medical visit during the acute phase to defervescence. The body temperature records were analyzed among 171 children of four age groups (< 6, < 12, < 24 and ≥ 24 months), in terms of fever development, degrees of fever onset, the highest fever during the period, and fever duration. There were 54 patients in the group of < 6 months, 41 in the group of < 12 months, 58 in the group of < 24 months, and 18 in the group of ≥ 24 months. We thus found the correlation between age and fever responses under 24 months old; namely, the more the age advanced, the more frequently high and prolonged fever was experienced. Importantly, infants under 6 months old tend to show the suppressed fever responses. In conclusion, young infants with reduced fever response during RSV infection do not implicate less severity and needs attentive management.

keywords —— fever; fever duration; fever responses; pediatrics; respiratory syncytial virus

© 2018 Tohoku University Medical Press

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Tohoku J. Exp. Med., 2018, 245, 217-222

Correspondence: Chiaki Kawakami, Department of Pediatrics, Yokosuka Kyosai Hospital, 1-16 Yonegahama-dori, Yokosuka, Kanagawa 238-8558, Japan.
*Present address: Field Epidemiology Training Program (FETP), Infectious Disease Surveillance Center, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.l, Tokyo Medical and Dental University, 1-545 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.

e-mail: ckawakami25@gmail.com

Masaaki Mori, M.D. Ph.D., Department of Lifetime Clinical Immunology, Graduate School, Tokyo Medical and Dental University, 1-545 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.

e-mail: mori.phv@tmd.ac.jp