SPATIAL AND TEMPORAL ANALYSIS OF CUTANEOUS LEISHMANIASIS INCIDENCE IN SAO PAULO - BRAZIL

摘要

Cutaneous Leishmaniasis transmission occurs in a complex cycle where the environment has a significant influence. Some important parameters related to this cycle can be qualified and quantified with Remote Sensing and Geoprocessing, employed to study 27 cases of CL occurred at Itapira municipality (Sao Paulo/Brazil), reported between 1992 and 1997. Forest remnants related to these cases were delimited and the distances between dwellings and remnants were calculated. Contact Risk Zones were defined taking the remnants border and expanding it, according to criteria based on the mosquitoes flight range. Also, the influence of vegetation density and deforestation on the CL incidence was analyzed through: 1) a Normalized Difference Vegetation Index (NDVI) and 2) a Multitemporal Principal Component Analysis (PCA). The relative percentages of NDVI classes found around the remnants showed a high Vegetation Index in this region, varying between 0.45 and 1.0 in approximately 50percent of remnant surrounding areas. The Second Principal Component derived from PCA was used to determine the areas where deforestation seems to have an important role in CL incidence. The analysis carried out indicate that three types of transmission may be occurring in that region: (i) an intra-forest transmission in locals where a disease focus was localized within a dispersion radius of the mosquito; (ii) an extra-forest transmission probably related to the existence of a high percentage of dense vegetation around remnants where the mosquito can flight and (iii) transmission in human dwellings, possibly caused by a mosquito domestication process.