Murakami Yoshitaka, Hashimoto Shuji, Ohta Akiko, Kawado Miyuki, Izumida Michiko, Tada Yuki, Shigematsu Mika, Yasui Yoshinori, Taniguchi Kiyosu, Nagai Masaki
Department of Health Science, Shiga University of Medical Science, Seta Tsuikinowa-cho, Otsu City, Shiga 520-2192, Japan.
J Epidemiol. 2007 Dec;17 Suppl(Suppl):S23-31. doi: 10.2188/jea.17.s23.
Epidemics of infectious diseases usually start in small areas and subsequently become widespread widely. Although a method for detecting epidemics in public health center (PHC) areas has been proposed and used in the National Epidemiological Surveillance of Infectious Diseases in Japan, wide-area epidemics have not been fully investigated.
Using the abovementioned method, we defined an epidemic as that occurring for a week in at least one PHC area in a prefecture and a wide-area epidemic as that when the number of people living in epidemic PHC areas exceeds 30% of the prefectural population. The number of weeks of an epidemic or wide-area epidemic for influenza and 11 pediatric diseases was observed in 47 prefectures in Japan from 1999 through 2005.
Epidemics and wide-area epidemics of influenza occurred for an average of 7.0 and 4.3 weeks in a year in a prefecture, respectively. The proportion of wide-area epidemics in epidemic weeks was 62%. The average number of wide-area epidemic weeks for pediatric diseases varied among diseases; it was more than 4 weeks for infectious gastroenteritis and herpangina and less than 1 week for pertussis, rubella, and measles. The proportion of wide-area epidemics in epidemic weeks was 28-41% for infectious gastroenteritis, hand-foot-mouth disease, and herpangina and less than 20% for other diseases.
The frequency of wide-area epidemics of influenza and pediatric diseases in various prefectures was observed. Epidemics of infectious diseases such as influenza and herpangina occurring in small areas were likely to spread to wide areas.
传染病流行通常始于小范围地区，随后广泛传播。尽管已提出一种在公共卫生中心（PHC）地区检测疫情的方法并在日本全国传染病流行病学监测中使用，但大范围疫情尚未得到充分调查。
使用上述方法，我们将疫情定义为在一个县的至少一个PHC地区持续一周的情况，将大范围疫情定义为疫情发生的PHC地区居住人数超过该县人口的30%的情况。观察了1999年至2005年日本47个县流感和11种儿科疾病的疫情或大范围疫情的周数。
一个县每年流感疫情和大范围疫情平均分别持续7.0周和4.3周。大范围疫情在疫情周数中的比例为62%。儿科疾病大范围疫情周数的平均数因疾病而异；感染性肠胃炎和疱疹性咽峡炎超过4周，百日咳、风疹和麻疹则不到1周。感染性肠胃炎、手足口病和疱疹性咽峡炎的大范围疫情在疫情周数中的比例为28%-41%，其他疾病则不到20%。
观察了各县流感和儿科疾病大范围疫情的发生频率。流感和疱疹性咽峡炎等在小范围地区发生的传染病疫情很可能蔓延至大范围地区。
