Spatial spread of dengue in a non-endemic tropical city in northern Argentina.

GIL, JF; PALACIOS, M; KROLEWIECKI, AJ; CORTADA, P; FLORES, R; JAIME, C; ARIAS, L; VILLALPANDO, C; ALBERTI D´AMATO, AM; NASSER, JR; APARICIO, JP

ACTA TROPICA

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 158 p. 24 - 31

0001-706X

After morethan eighty years dengue reemerged in Argentina in 1997. Since then, thelargest epidemic in terms of geographical extent, magnitude and mortality, wasrecorded 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 itscorrelation with demographic and socioeconomic factors. Cases were diagnosed byELISA between January and June 2009. We applied a space-time and spatial scanstatistic under a Poisson model. Possible association between dengue incidenceand socio-economic variables was studied with the Spearman correlation test.The epidemic started from an imported case from Bolivia and space-time analysisdetected two clusters: one on February and other in April (in the south and thenortheast of the city respectively) with risk ratios of 25.24 and 4.07(p <0.01). Subsequent cases spread widely around the city withoutsignificant space-temporal clustering. Maximum values of the entomologicalindices were observed in January, at the beginning of the epidemic(B = 21.96; LH = 8.39). No statistically significantassociation between socioeconomic variables and dengue incidence was found butpositive correlation between population size and the number of cases(p < 0.05) was detected. Two mechanisms may explain the observedpattern of epidemic spread in this non-endemic tropical city: a) Short rangedispersal of mosquitoes and people generates clusters of cases and b)long-distance (within the city) human movement contributes to a quasi-randomdistribution of cases.