A hospital-based surveillance for Japanese encephalitis in Bali, Indonesia.
BACKGROUND
Japanese encephalitis (JE) is presumed to be endemic throughout Asia, yet only a few cases have been reported in tropical Asian countries such as Indonesia, Malaysia and the Philippines. To estimate the true disease burden due to JE in this region, we conducted a prospective, hospital-based surveillance with a catchment population of 599,120 children less than 12 years of age in Bali, Indonesia, from July 2001 through December 2003.


METHODS
Balinese children presenting to any health care facility with acute viral encephalitis or aseptic meningitis were enrolled. A "confirmed" diagnosis of JE required the detection of JE virus (JEV)-specific IgM in cerebrospinal fluid, whereas a diagnosis of "probable JE" was assigned to those cases in which JEV-specific IgM was detected only in serum.


RESULTS
In all, 86 confirmed and 4 probable JE cases were identified. The annualized JE incidence rate was 7.1 and adjusted to 8.2 per 100,000 for children less than 10 years of age over the 2.5 consecutive years of study. Only one JE case was found among 96,920 children 10-11 years old (0.4 per 100,000). Nine children (10%) died and 33 (37%) of the survivors had neurological sequelae at discharge. JEV was transmitted in Bali year-round with 70% of cases in the rainy season.


CONCLUSIONS
JE incidence and case-fatality rates in Bali were comparable to those of other JE-endemic countries of Asia. Our findings contradict the common wisdom that JE is rare in tropical Asia. Hence, the geographical range of endemic JE is broader than previously described. The results of the study support the need to introduce JE vaccination into Bali.
Kari
Komang
K
Department of Pediatrics, Udayana University School of Medicine, Bali, Indonesia. Komang_Kari@yahoo.com
Liu
Wei
W
Gautama
Kompiang
K
Mammen
Mammen P
MP
Clemens
John D
JD
Nisalak
Ananda
A
Subrata
Ketut
K
Kim
Hyei Kyung
HK
Xu
Zhi-Yi
ZY
D002648:Child; D002675:Child, Preschool; D004672:Encephalitis, Japanese / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control; D005260:Female; D006761:Hospitals; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood; D007214:Indonesia; D007223:Infant; D007231:Infant, Newborn; D022321:Japanese Encephalitis Vaccines / Q000627:therapeutic use; D008297:Male; D011446:Prospective Studies
D007075:Immunoglobulin M; D022321:Japanese Encephalitis Vaccines