LETTERS

High Incidence of Biologic Products, Chengdu, China) were tested for antibodies against JE has been included in the national virus, mumps virus, echoviruses, and Japanese Expanded Program on Immunization coxsackieviruses (3,4,7). A case of JE Encephalitis, at no charge. The recommendation for was defined as illness in a person with Southern China children is vaccination at 8 months IgM against JEV in CSF or serum. and 2 years of age (5,6). Clinical information was collected by To the Editor: Japanese To estimate JE incidence in using a standardized chart abstraction encephalitis virus (JEV) remains a Dehong Prefecture during January form. Linkages to personal identifiers major source of illness and death in Asia 1–December 31, 2010, we conducted were destroyed. (1). An estimated 67,900 cases occur an anonymous, unlinked study of A total of 189 eligible patients each year in Asia; ≈33,900 cases— all cases of encephalitis at the only were enrolled, 150 from Mangshi half the cases in the world—probably 2 major children’s hospitals in the and 39 from Ruili. Of these, 110 occur in the People’s Republic of region, Dehong Prefecture Hospital (58%) were male and 78 (41%) were China (2). However, because reporting in Mangshi and Ruili City Hospital in <4 years of age. Enrollment peaked is incomplete in most countries where Ruili. All eligible patients admitted to during summer (Figure). All patients JE incidence is high, these estimates these hospitals were included in the were hospitalized within 6 days after are based on scarce data. In China, a study. Inclusion criteria were age <15 symptom onset. A total of 22 (12%) study conducted during 2006–2007 in years, residency in Dehong Prefecture, patients were classified as having JE sentinel hospitals in 1 prefecture each clinical diagnosis of encephalitis, on the basis of IgM, in CSF for 21 and in Shandong, Hubei, Guangxi, and lumbar puncture performed (routine in serum for 1. Illness onset occurred Hebei Provinces (all in the eastern half for encephalitis patients at these 2 during May–November (Figure); of China) found that 9.2% of patients hospitals), and cerebrospinal fluid overall incidence was 10.4 cases per with acute meningitis and encephalitis (CSF) pleocytosis. After routine 100,000 children <15 years of age. had JEV; adjusted incidence for each testing was completed, leftover CSF Among these 22 children with JE, 11 prefecture was 0.08–1.58 cases per and serum samples were stored at were male; 20 were from rural areas; 100,000 population (3). Incidence -70°C until further testing, which was 14 were from Mangshi and 8 were in these 4 prefectures is lower than all conducted at the Chinese Center from Ruili; and 5 were 0–1 years, 6 that among children <14 years of for Disease Control and Prevention in were 2–4 years, and 11 were 5–13 years age in JE-endemic countries, where Beijing. All CSF specimens were tested of age. JEV vaccination history was estimated incidence is 5.4 cases per by viral culture in C6/36 and BHK- infrequently recorded in the medical 100,000 population (2). To assess 21 cells (7) and tested for antibodies charts; however, JEV was more likely the need for strengthening existing against JEV (3,4). Serum samples to be the cause of encephalitis among JE surveillance and vaccination programs, we conducted a population- based 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 Figure. Number of children with encephalitis at 2 hospitals, by etiology and month of symptom JEV vaccine (Chengdu Institute of onset, Dehong Prefecture, People’s Republic of China, 2010.

672 Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 19, No. 4, April 2013 LETTERS children who received no vaccination Baoqing Dao, Kunhong Li, 7. Xufang Y, Huanyu W, Shihong F, Xiaoyan (22%, 6/27) than among those with Na Li, Zhengliu Yin, G, Shuye Z, Chunting L, et al. Etiological spectrum of clinically diagnosed unknown vaccination history (10%, Yonghua Liu, Roger Nasci, Japanese encephalitis cases reported in 15/157). Of 5 vaccinated children, 1 Huanyu Wang, Guizhou Province, China, in 2006. J Clin had JE; however, verification of this and Guodong Liang Microbiol. 2010;48:1343–9. http://dx.doi. org/10.1128/JCM.01009-09 child’s vaccination was not possible. Author affiliations: Yunnan Institute of Among 71 children who had no Endemic Disease Control and Prevention, Address for correspondence: Guodong Liang, evidence of JE but for whom serum Dali, People’s Republic of China. (Y. Feng, State Key Laboratory for Infectious Disease samples were available for testing, 5 H. Zhang, W. Yang, Y. Zhang); National Prevention and Control, Institute for Viral had antibodies against mumps virus, Institute for Viral Disease Control and Disease Control and Prevention, Chinese Center 8 against echoviruses, and 5 against Prevention of the Chinese Center for for Disease Control and Prevention, Beijing coxsackieviruses. Viral cultures of CSF Disease Control and Prevention, Beijing, 100052, People’s Republic of China; email: from all 189 children were negative. China (S. Fu, X. Gao, H. Wang, G. Liang); [email protected] Our finding of 10.4 JE cases per Centers for Disease Control and Prevention, 100,000 children <15 years of age in Fort Collins, Colorado, USA (L.R. Petersen, Dehong Prefecture is higher than the R. Nasci); Dehong Prefecture Center for estimated incidence of 5.4 cases per Disease Control and Prevention, Mangshi, 100,000 population among children China (B. Zhang, B. Dao, K. Li, N Li); <14 years of age in JE-endemic and Ruili Center for Disease Control and countries (2). Nevertheless, the true Prevention, Ruili, China (Z. Yin, Y. Liu) Novel Hantavirus JE population incidence for Dehong in Field Vole, Prefecture might be underestimated 1These authors contributed equally to this if some children received no medical article. United Kingdom care or were admitted to other DOI: http://dx.doi.org/10.3201/eid1904.120137 To the Editor: Hantaviruses hospitals. Adults were not studied; (family Bunyaviridae) are transmit- however, ≈90% of JE cases in China References ted to humans by inhalation of aero- are reported among children <15 years solized virus in contaminated urine of age (5,6). Unfortunately, accurate 1. Erlanger TE, Weiss S, Keiser J, Utzinger and feces, mainly from rodents of the age-adjusted JE vaccination coverage J, Wiedenmayer K. Past, present, and families Cricetidae and Muridae. Al- future of Japanese encephalitis. Emerg data for Dehong Prefecture are not though infections in rodents are as- available. Although vaccination Infect Dis. 2009;15:1–7. http://dx.doi. org/10.3201/eid1501.080311 ymptomatic, infections in humans can programs have markedly lowered JE 2. Campbell GL, Hills SL, Fischer M, lead to hemorrhagic fever with renal incidence in China in recent years Jacobson JA, Hoke CH, Hombach JM, et syndrome and hantavirus cardiopul- al. Estimated global incidence of Japanese (5,6), the finding of continuing high monary syndrome (1). JE incidence in Dehong Prefecture encephalitis: a systematic review. Bull World Health Organ. 2011;89:766–774. In Europe, 5 rodent-borne hanta- warrants further attention. http://dx.doi.org/10.2471/BLT.10.085233 viruses have been detected: Dobrava- 3. Yin Z, Wang HY, Yang JY, Luo H, Hadler Belgrade, Saaremaa, Seoul, Puumala, This work was supported by grants SC, Sandhu HS, et al. Japanese encephalitis and Tula (1,2). The most common from The Chinese Center for Disease Con- disease burden and clinical features of Japanese encephalitis in four cities in the and widespread hantavirus in Europe trol and Prevention–US Centers for Dis- People’s Republic of China. Am J Trop is Puumala virus, which is associated ease Control and Prevention Cooperative Med Hyg. 2010;83:766–73. http://dx.doi. with the mildest form of hemorrhagic Agreement (U19-GH000004); the Min- org/10.4269/ajtmh.2010.09-0748 fever with renal syndrome (1). istry of Science and Technology, China 4. Wang J, Zhang H, Sun X, Fu S, Wang H, Feng Y, et al. Distribution of mosquitoes In the United Kingdom, only a (2011CB504702); development grant of the and mosquito-borne arboviruses in few cases of hantavirus infection in State Key Laboratory for Infectious Disease Yunnan Province near the China– humans have been reported and con- Prevention and Control (2008SKLID105); Myanmar–Laos border. Am J Trop Med firmed serologically, but the caus- and the National Natural Science Founda- Hyg. 2011;84:738–46. http://dx.doi. org/10.4269/ajtmh.2011.10-0294 ative virus species were not identified tion of China (31070145). 5. Gao X, Nasci R, Liang GD. The neglected (3,4). Subsequent longitudinal stud- arboviral infections in mainland China. ies reported considerable hantavirus Yun Feng,1 Shihong Fu,1 PLoS Negl Trop Dis. 2010;4:e624. http:// dx.doi.org/10.1371/journal.pntd.0000624 seropositivity among healthy human Hailin Zhang, Lyle R. Petersen, 6. Wang H, Li Y, Liang X, Liang G. Japanese cohorts, suggesting past exposure to Baosen Zhang, Xiaoyan Gao, encephalitis in mainland China. Jpn J hantaviruses or subclinical infection Weihong Yang, Yuzhen Zhang, Infect Dis. 2009;62:331–6. (3). Serologic surveys of rodents (rats

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