Temporal and spatial patterns of malaria reinfection in northeastern Venezuela.

Abstract

Abstract. We stratified the risk of malaria transmission (Plasmodium vivax) in 35 villages along a coastal range in northeastern Venezuela (51 km 2 ) where the main vector is the mosquito Anopheles aquasalis. After 20 years without local malaria transmission, reinfection of the entire area occurred from May to December 1985 by local (continuous) and jump (discontinuous) dispersal. Epidemiologic, environmental, and vector variables were investigated with the aid of a Geographic Information System. Risk factors for malaria transmission were human population density, proximity to pre-adult mosquito habitats (Ͻ 500 m), and the number of pre-adult habitats nearby. Most inhabitants, immature mosquito habitats, and malaria cases were located at low elevations and on gentle slopes. High prevalence of malaria during the dry seasons was associated with the presence of permanent bodies of water containing An. aquasalis. Occurrence of a La Niña event in 1988 (wet and cool phase of the El Niño Southern Oscillation) triggered malaria transmission to unusually high levels, consolidating infection in the area, and rendering traditional control efforts useless. We recommend tracking malaria persistence per village and associated risk factors as methods to reduce the cost of malaria control programs.A malaria focus is a circumscribed locality situated in a current or former malarious area that includes the epidemiologic factors necessary for malaria transmission. These include a human community, at least 1 source of infection, a vector population, and the appropriate environmental conditions.

Disentangling the Effect of Local and Global Spatial Variation on a Mosquito-Borne Infection in a Neotropical Heterogeneous Environment

“…1 The dependence of malaria transmission on its spatial and ecological context has long been recognized; hence, the need to study this disease within its explicit spatial context. [2][3][4][5] Transmission of mosquito-borne pathogens can be highly heterogeneous caused by a complex set of interactions among parasites, vectors, and hosts occurring at specific locations (both natural and anthropogenic landscapes), and at specific times. [6][7][8] Efficient control of this disease and prediction of its emergence or spread to new geographic regions require an understanding of the effect of spatial heterogeneity on malaria transmission dynamics.…”

Análise espacial da transmissão de dengue em cidade de porte médio do interior paulista

“…It has shown that transmission does not occur uniformly across the municipality. The analyses proposed by Barrera et al 1,2 are interesting means for continuing the study. The aim would be to identify census tracts, groups of tracts, or districts that are priority areas for the surveillance and control of dengue.…”

“…Barrera et al 1,2 proposed the identification of socalled "hot spots" within a single municipality or region. These would be the places responsible both for the majority of cases and for the continuation of transmission during less favorable periods.…”

The Epidemiology of Malaria in Belize, 1989-1999

“…Transmission variation may be associated with many factors, for example landscape variables, vector ecology, and human population density (Barrera et al 1999). An understanding of the factors influencing the variation in transmission patterns within localities and regions will help in developing an effective malaria control program.…”