Japanese encephalitis virus remains an important cause of encephalitis in Thailand.
BACKGROUND
Japanese encephalitis virus (JEV) is endemic in Thailand and prevention strategies include vaccination, vector control, and health education.


METHODS
Between July 2003 and August 2005, we conducted hospital-based surveillance for encephalitis at seven hospitals in Bangkok and Hat Yai. Serum and cerebrospinal (CSF) specimens were tested for evidence of recent JEV infection by immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) and a plaque reduction neutralization test (PRNT).


RESULTS
Of the 147 patients enrolled and tested, 24 (16%) had evidence of acute flavivirus infection: 22 (15%) with JEV and two (1%) with dengue virus. Of the 22 Japanese encephalitis (JE) cases, 10 (46%) were aged ≤ 15 years. The median length of hospital stay was 13 days; one 13-year-old child died. Ten percent of encephalitis patients enrolled in Bangkok hospitals were found to have JEV infection compared to 28% of patients enrolled in hospitals in southern Thailand (p < 0.01). Four (40%) of the 10 children with JE were reported as being vaccinated.


CONCLUSIONS
JEV remains an important cause of encephalitis among hospitalized patients in Thailand. The high proportion of JE among encephalitis cases is concerning and additional public health prevention efforts or expanded vaccination may be needed.
Olsen
Sonja J
SJ
Divison of Emerging Infections and Surveillance Services, Centers for Disease Control and Prevention Collaboration, 1600 Clifton Road, MS C-12, Atlanta, GA 30333, USA. SOlsen@cdc.gov
Supawat
Krongkaew
K
Campbell
Angela P
AP
Anantapreecha
Surapee
S
Liamsuwan
Sahas
S
Tunlayadechanont
Supoch
S
Visudtibhan
Anannit
A
Lupthikulthum
Somsak
S
Dhiravibulya
Kanlaya
K
Viriyavejakul
Akravudh
A
Vasiknanonte
Punnee
P
Rajborirug
Kiatsak
K
Watanaveeradej
Veerachai
V
Nabangchang
Chacrin
C
Laven
Janeen
J
Kosoy
Olga
O
Panella
Amanda
A
Ellis
Christine
C
Henchaichon
Sununta
S
Khetsuriani
Nino
N
Powers
Ann M
AM
Dowell
Scott F
SF
Fischer
Marc
M
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D004664:Encephalitis Virus, Japanese / Q000276:immunology / Q000302:isolation & purification*; D004672:Encephalitis, Japanese / Q000453:epidemiology* / Q000517:prevention & control / Q000821:virology; D006801:Humans; D007223:Infant; D022321:Japanese Encephalitis Vaccines / Q000627:therapeutic use; D008875:Middle Aged; D013785:Thailand / Q000453:epidemiology; D055815:Young Adult
D022321:Japanese Encephalitis Vaccines