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Volume 23, Number 11—November 2017
Dispatch

Virulence of Japanese Encephalitis Virus Genotypes I and III, Taiwan

Yi-Chin Fan1, Jen-Wei Lin1, Shu-Ying Liao, Jo-Mei Chen, Yi-Ying Chen, Hsien-Chung Chiu, Chen-Chang Shih, Chi-Ming Chen, Ruey-Yi Chang, Chwan-Chuen King, Wei-June Chen, Yi-Ting Ko, Chao-Chin Chang, and Shyan-Song ChiouComments to Author 
Author affiliations: National Chung Hsing University, Taichung, Taiwan (Y.-C. Fan, J.-W. Lin, S.-Y. Liao, J.-M. Chen, Y.-Y. Chen, C.-M. Chen, Y.-T. Ko, C.-C. Chang, S.-S. Chiou); National Defense Medical Center, Taipei, Taiwan (H.-C. Chiu); Tri-Service General Hospital (H.-C. Chiu); Taiwan Mennonite Christian Hospital, Hualien, Taiwan (C.-C. Shih); Tungs’ Taichung MetroHarbor Hospital, Taichung (C.-M. Chen); National Dong Hwa University, Hualien (R.-Y. Chang); National Taiwan University, Taipei (C.-C. King); Chang Gung University, Taoyuan, Taiwan (W.-J. Chen)

Main Article

Table 2

Estimated incidence of infection and asymptomatic ratios of JEV genotypes I and III among study populations, Taiwan*

Region
Characteristic
 Changhua
 Taipei
 Pingtung
 Miaoli
 Taichung
 Hualien
 Taichung
 Hualien
 p value†
Year
 1994
 1995
 1999
 2000
 2010
 2010
 2012
 2012
 ND
No. specimens (incidence of infection)
 966 (171)
 974 (88)
 638 (67)
 411 (137)
 656 (146)
 905 (151)
 632 (105)
 375 (75)
 ND
NT positive, %
 62
 69
 60
 58
 65
 75
 72
 66
 <0.05
IgM positive, % (A)
 4.91
 0.90
 1.93
 1.10
 0.98
 2.25
 3.23
 3.67
 <0.05
Seroconversion + 
≥4-fold increase in 
NT titer, %‡ (B)
 0.58
 1.13
 0
 0.73
 1.37
 1.32
 0.95
 1.33
 >0.05
Incidence of infection, % (C = A + B)
 5.49
 2.03
 1.93
 1.83
 2.35
 3.57
 4.18
 5.00
 <0.05
Population§ (D)
 483,766
 2,643,221
 909,778
 559,703
 598,186
 339,659
 593,780
 337,382
 ND
Predicted no. infections (E = C × D)
 26,559
 53,657
 17,559
 10,243
 14,057
 12,126
 24,820
 16,869
 ND
Confirmed cases (F)¶
 4
 3
 2
 1
 2
 2
 2
 2
 ND
Asymptomatic ratio (G = F/E)
 1/6,640
 1/17,886
 1/8,779
 1/10,243
 1/7,029
 1/6,063
 1/12,410
 1/8,435
 >0.05
Asymptomatic ratio, 
95% CI 1/5,102–1/8,000 1/15,408–1/21,322 1/8,000–1/9,709 1/8,065–1/13,947 1/6,329–1/7,874 1/5,348–1/6,993 1/10,846–1/14,493 1/7,299–1/10,010 ND

*Serum samples were collected after the Japanese encephalitis season (May–September); multiple serum samples were collected from some participants. JEV, Japanese encephalitis virus; ND, no data; NT, neutralizing antibody.
†Analyzed by using one-way analysis of variance.
‡Among the IgM-negative population, JEV infection was estimated by the observation of an increase in the NT titer, including seroconversion and ≥4-fold increase in the NT titer among subjects with multiple serum samples.
§In Taichung, only residents of the districts around the serum-collecting hospital were included.
¶According to the official report of the Taiwan Centers for Disease Control.

Main Article

1These authors contributed equally to this article.

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Page updated: October 17, 2017
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