Distinctive clinical features of human bocavirus in children younger than 2 years

Moriyama, Yoko; Hamada, Hiromichi; Okada, Mineyuki; Tsuchiya, Nozomi; Maru, Hiromi; Shirato, Yuri; Maeda, Yasuhiro; Hirose, Yosuke; Yoshida, Masaki; Omura, Yoh; Honda, Takafumi; Muto, Ayako; Hayashi, Kitami; Terai, Masaru

Regarding the HBoV seasonality, its peak was similar to that identified in a previous study in northern Japan. In the study, HBoV-positive patients were most prevalent during January-May. The peak occurred during April-May in Japan [17] . The seasons are important diagnostic information in Japan. In France, the seasonal distribution is November-June; the peak occurs in March-April [15] , which resembles the circumstances in Japan. In Hong Kong and Thailand, the peak seasons were in fall and winter, respectively [8, 14] . Specific examination of extremely young patients revealed a clear difference in the age distribution of HBoV-positive patients from that of RSV. In RSV-positive patients, 44% of all patients were younger than 6 months. In contrast, the minimum age of HBoV-positive patients was 5 months. Endo et al. measured the levels of the antibody in human serum samples aged from 0 months to 41 years and reported that the seropositive rate was lowest in the age group of 6-8 months [12] . These data suggest that infants younger than 6 months might be protected from HBoV infection.