title: Geographic trends and spread of the pandemic (H1N1) 2009 in the metropolitan areas of Japan studied from the national sentinel data.
abstract: The identification of geographic trends of an influenza pandemic is important for  analyzing its social epidemic factors. We performed spatiotemporal analyses focusing on the  metropolitan areas in Japan by using the influenza-like illness (ILI) sentinel surveillance data  for the pandemic (H1N1) 2009 and seasonal influenza. The epidemic curves and spread features  expressed by the kriging method of geographic information system (GIS) and correlations between  reported cases and demographic data were analyzed. The incidence of pandemic (H1N1) 2009 increased  gradually at the beginning and showed more sporadic epidemic features compared to seasonal influenza.  However, there were coincidental locations of patient clusters affected by the seasonal influenza,  with a significant coefficient for the total sentinel reported cases (r = 0.71, P < 0.01). This  suggested similar patterns of the epidemic over seasons. Patient clusters tended to be located in  suburban areas, and there seemed to be stronger relationships between epidemics and higher ratio of  larger families (with r = 0.26-0.35, P < 0.01, between ratio of families having more than 3 members  and total reported cases in Tokyo and Nagoya areas). Whether populous areas had a greater  probability of maintaining the epidemic patterns needs to be determined. Nonetheless, the patterns  found in this study can be useful for further analyses for epidemic modeling and designing relevant  controls.
authors: Infectious Disease Surveillance Center, National Institute of Infectious Diseases, Tokyo, Japan. inaida＠nih.go.jp
authors: Shinako
authors: S
authors: Inaida
authors: Yoshinori
authors: Y
authors: Yasui
authors: Yuki
authors: Y
authors: Tada
authors: Kiyosu
authors: K
authors: Taniguchi
authors: Nobuhiko
authors: N
authors: Okabe
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D005843:Geography; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification*; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology*; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D058873:Pandemics; D018571:Sentinel Surveillance; D013997:Time Factors; D055815:Young Adult