title: Spatial spread of dengue in a non-endemic tropical city in northern Argentina.
abstract: After more than eighty years dengue reemerged in Argentina in 1997. Since then, the largest epidemic in terms of geographical extent, magnitude and mortality, was recorded in 2009. In this report we analyzed the DEN-1 epidemic spread in Orán, a mid-size city in a non-endemic tropical area in Northern Argentina, and its correlation with demographic and socioeconomic factors. Cases were diagnosed by ELISA between January and June 2009. We applied a space-time and spatial scan statistic under a Poisson model. Possible association between dengue incidence and socio-economic variables was studied with the Spearman correlation test. The epidemic started from an imported case from Bolivia and space-time analysis detected two clusters: one on February and other in April (in the south and the northeast of the city respectively) with risk ratios of 25.24 and 4.07 (p<0.01). Subsequent cases spread widely around the city without significant space-temporal clustering. Maximum values of the entomological indices were observed in January, at the beginning of the epidemic (B=21.96; LH=8.39). No statistically significant association between socioeconomic variables and dengue incidence was found but positive correlation between population size and the number of cases (p<0.05) was detected. Two mechanisms may explain the observed pattern of epidemic spread in this non-endemic tropical city: a) Short range dispersal of mosquitoes and people generates clusters of cases and b) long-distance (within the city) human movement contributes to a quasi-random distribution of cases.
authors.affiliation: Instituto de Investigaciones en Enfermedades Tropicales, Sede Regional Orán, Universidad Nacional de Salta, 4530 Salta, Argentina; Instituto de Investigaciones en Energía no Convencional (INENCO-CONICET), Universidad Nacional de Salta, 4400 Salta, Argentina. Electronic address: jgil@conicet.gov.ar.
authors.forename: José F
authors.initials: JF
authors.lastname: Gil
authors.affiliation: Instituto de Investigaciones en Energía no Convencional (INENCO-CONICET), Universidad Nacional de Salta, 4400 Salta, Argentina. Electronic address: palaciosmaxi@gmail.com.
authors.forename: Maximiliano
authors.initials: M
authors.lastname: Palacios
authors.affiliation: Instituto de Investigaciones en Enfermedades Tropicales, Sede Regional Orán, Universidad Nacional de Salta, 4530 Salta, Argentina; Instituto de Patología Experimental, Facultad de Ciencias de la Salud, Universidad Nacional de Salta, 4400 Salta, Argentina. Electronic address: alekrol@hotmail.com.
authors.forename: Alejandro J
authors.initials: AJ
authors.lastname: Krolewiecki
authors.affiliation: Hospital San Vicente de Paul, San Ramón de la Nueva Orán, 4530 Salta, Argentina. Electronic address: pacortada@yahoo.com.ar.
authors.forename: Pedro
authors.initials: P
authors.lastname: Cortada
authors.affiliation: Hospital San Vicente de Paul, San Ramón de la Nueva Orán, 4530 Salta, Argentina. Electronic address: floresleticiarosana@gmail.com.
authors.forename: Rosana
authors.initials: R
authors.lastname: Flores
authors.affiliation: Hospital San Vicente de Paul, San Ramón de la Nueva Orán, 4530 Salta, Argentina. Electronic address: cejaime_2012@live.com.
authors.forename: Cesar
authors.initials: C
authors.lastname: Jaime
authors.affiliation: Hospital San Vicente de Paul, San Ramón de la Nueva Orán, 4530 Salta, Argentina. Electronic address: luisarias56@yahoo.com.ar.
authors.forename: Luis
authors.initials: L
authors.lastname: Arias
authors.affiliation: Hospital San Vicente de Paul, San Ramón de la Nueva Orán, 4530 Salta, Argentina; Instituto de Investigaciones en Enfermedades Tropicales, Sede Regional Orán, Universidad Nacional de Salta, 4530 Salta, Argentina. Electronic address: cavillalpando@yahoo.com.ar.
authors.forename: Carlos
authors.initials: C
authors.lastname: Villalpando
authors.affiliation: Instituto de Patología Experimental, Facultad de Ciencias de la Salud, Universidad Nacional de Salta, 4400 Salta, Argentina. Electronic address: anahialberti@hotmail.com.
authors.forename: Anahí M
authors.initials: AM
authors.lastname: Alberti DÁmato
authors.affiliation: Instituto de Investigaciones en Enfermedades Tropicales, Sede Regional Orán, Universidad Nacional de Salta, 4530 Salta, Argentina. Electronic address: jrnasser@hotmail.com.
authors.forename: Julio R
authors.initials: JR
authors.lastname: Nasser
authors.affiliation: Instituto de Investigaciones en Energía no Convencional (INENCO-CONICET), Universidad Nacional de Salta, 4400 Salta, Argentina; Mathematical, Computational and Modeling Sciences Center, Arizona State University, PO Box 871904, Tempe, AZ 85287-1904, USA. Electronic address: juan.p.aparicio@gmail.com.
authors.forename: Juan P
authors.initials: JP
authors.lastname: Aparicio
mesh_terms: D000293:Adolescent; D000328:Adult; D000330:Aedes / Q000821:virology*; D000367:Age Factors; D000368:Aged; D000818:Animals; D001118:Argentina / Q000453:epidemiology; D002648:Child; D002947:Cities / Q000453:epidemiology*; D003715:Dengue / Q000453:epidemiology* / Q000635:transmission*; D003716:Dengue Virus / Q000302:isolation & purification*; D004196:Disease Outbreaks; D005260:Female; D005843:Geography; D006801:Humans; D015994:Incidence; D007814:Larva / Q000821:virology*; D008297:Male; D008875:Middle Aged; D011156:Population Density; D012111:Residence Characteristics; D012621:Seasons; D012959:Socioeconomic Factors; D062211:Spatio-Temporal Analysis; D055815:Young Adult
keywords: Aedes aegypti; Dengue; Larval indexes; Non-endemic city; Spatial analysis