Multi-level analyses of spatial and temporal determinants for dengue infection.
BACKGROUND
Dengue is a mosquito-borne viral infection that is now endemic in most tropical countries. In Thailand, dengue fever/dengue hemorrhagic fever is a leading cause of hospitalization and death among children. A longitudinal study among 1750 people in two rural and one urban sites in northern Thailand from 2001 to 2003 studied spatial and temporal determinants for recent dengue infection at three levels (time, individual and household).


METHODS
Determinants for dengue infection were measured by questionnaire, land-cover maps and GIS. IgM antibodies against dengue were detected by ELISA. Three-level multi-level analysis was used to study the risk determinants of recent dengue infection.


RESULTS
Rates of recent dengue infection varied substantially in time from 4 to 30%, peaking in 2002. Determinants for recent dengue infection differed per site. Spatial clustering was observed, demonstrating variation in local infection patterns. Most of the variation in recent dengue infection was explained at the time-period level. Location of a person and the environment around the house (including irrigated fields and orchards) were important determinants for recent dengue infection.


CONCLUSIONS
We showed the focal nature of asymptomatic dengue infections. The great variation of determinants for recent dengue infection in space and time should be taken into account when designing local dengue control programs.
Vanwambeke
Sophie O
SO
Department of Geography, Université Catholique de Louvain, Place Pasteur, 3, 1348 Louvain-la-Neuve, Belgium. vanwambeke@geog.ucl.ac.be
van Benthem
Birgit H B
BH
Khantikul
Nardlada
N
Burghoorn-Maas
Chantal
C
Panart
Kamolwan
K
Oskam
Linda
L
Lambin
Eric F
EF
Somboon
Pradya
P
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D003715:Dengue / Q000453:epidemiology* / Q000276:immunology; D005260:Female; D040362:Geographic Information Systems; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012044:Regression Analysis; D012621:Seasons; D013029:Space-Time Clustering; D014887:Weather