High Incidence of Japanese Encephalitis, Southern China

To the Editor: Japanese encephalitis virus (JEV) remains a major source of illness and death in Asia (1).An estimated 67,900 cases occur each year in Asia; ≈33,900 caseshalf the cases in the world-probably occur in the People's Republic of China (2).However, because reporting is incomplete in most countries where JE incidence is high, these estimates are based on scarce data.In China, a study conducted during 2006-2007 in sentinel hospitals in 1 prefecture each in Shandong, Hubei, Guangxi, and Hebei Provinces (all in the eastern half of China) found that 9.2% of patients with acute meningitis and encephalitis had JEV; adjusted incidence for each prefecture was 0.08-1.58cases per 100,000 population (3).Incidence in these 4 prefectures is lower than that among children <14 years of age in JE-endemic countries, where estimated incidence is 5.4 cases per 100,000 population (2).To assess the need for strengthening existing JE surveillance and vaccination programs, we conducted a populationbased study of JE incidence in 1 area of southern China.Dehong is a prefecture in western Yunnan Province, which borders Myanmar.The JE-susceptible population of Dehong Prefecture (residents <15 years of age) is 211,337.The 2 principal cities of Dehong Prefecture-Mangshi and Ruili-are busy commercial centers surrounded by areas of extensive rice cultivation.The mosquito vector of JEV, Culex tritaeniorhynchus, is predominant during summer (4).During 1988-2007, JEV vaccination was available only at certain clinics and only for a fee; however, since 2008, vaccination with the live, attenuated SA 14-14-2 JEV vaccine (Chengdu Institute of