ABSTRACT
OBJECTIVE: To study the spatiotemporal trend of Japanese encephalitis in Guangxi Zhuang Autonomous Region between 1989 and 2006. METHODS: Retrospective space-time permutation scan statistic and inverse distance weighted (IDW) interpolation were employed to detect the spatiotemporal trend of Japanese encephalitis in Guangxi, from the year 1989 to 2006. RESULTS: The spatiotemporal pattern of Japanese encephalitis was divided into four phases by IDW interpolation maps, from 1989 to 2006. The first phase was spatiotemporal cluster located in southeast region, from 1989 to 1996. The second phase showed discrete distribution from 1997 to 1998. The third phase of spatiotemporal cluster located in Lingshan county, Pubei county and Bobai county, in 1999. And the last phase was spatiotemporal cluster located in northwest region from 2000 to 2006. Three statistically significant spatiotemporal clusters were detected by retrospective space-time permutation scan statistic. The primary cluster appeared in 1999 (LLR = 253.25, P = 0.001, RR = 4.62), with 109°54' E, 22°28' N (located in Pubei county) as its center and radiated 45.24 km. From 2000 to 2006, the secondary cluster showed in northwest (LLR = 75.91, P = 0.001, RR = 1.88), with center located at 105° 23' E, 24° 68' N (Longlin county), and radiated 199.85 km. From 1989 to 1996, the other secondary cluster appeared in the southeast area (LLR = 46.29, P = 0.001, RR = 1.16), with center located at 110°94' E, 24°03' N (Zhaoping county) and radiated 229.12 km. CONCLUSION: Space-time permutation scan statistic and geographical information system could be applied to quantitatively detect the potentially spatiotemporal trend of the disease. The spatiotemporal cluster shifted from southeast to northwest, from 1989 to 2006.
