1. Graduate School of Environmental & Symbiotic Sciences, Prefectural University of Kumamoto, 3-1-100, Tsukide, Higashi-ku, Kumamoto 862-8502, Japan
2. Public Health and Disease Prevention Division, Ariake Public Health Center, Kumamoto Prefectural Government, 1004-1, Iwasaki, Tamana, Kumamoto 865-0016, Japan