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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B4. Istanbul 2004
Some of the C/ippings (A, B, C, D, E, G e H) inserted in re-
vegetation area presented also some of the higher deforestation
index (Table 1). The average of total deforested area (4 and 5
PC2 classes) percentage among these Clippings was 14.35%,
while the average of the total re-vegetation area percentage
among them was 12.24%.
The other Clippings are found in the region where the altitudes
are higher. In this case the average of the total deforested area
percentage was 18.67% and the average of the total re-
vegetation area percentage was 8.60%. D, E and F Clippings
seem to be associated to a greater deforestation occurred in the
area where they are found. The same thing probably occurs
with M, N, O and P Clippings.
4 — CONCLUSIONS
The results initially demonstrated that the transmission has not
occurred only inside the normal flight range of Phlebotominae
mosquitoes (about 250 meters). The high NDVI indices found
around the fragments could be indicating that it is necessary to
have enough green density around the fragments in order to the
mosquito be able to reach human dwellings, amplifying its
average flight range. This makes it possible to suggest a
landscape pattern where the incidence of the disease would be
related not only to the presence of woods, but also to the
presence of other kinds of vegetation spread around the
fragments, as long as it is dense enough.
The reason why the areas with larger deforestation indices are
concentrated on Center-East region of Itapira could be linked to
the fact that a great portion of wood areas had already been
deforested before 1992 in lower altitudes, remaining the areas
of restricted access, in higher altitudes, in the Center-East
region, that is now deforested. It could be possible to assume
that, if the influence of the vegetation density in the presence of
the mosquito was to be considered, and the Second
Deforestation Limit is indicator that there was denser vegetation
in 1992, the relative areas to this limit also can be directly
related to the alterations in CL incidence. Therefore, the fact of
the Clippings sets {D, E, F} and {M, N, O, P} being associated
to the areas where the biggest rates of the Second Deforestation
Limit occurred, it seems to indicate a relation between these
cases and the deforestation.
PCA analysis showed that in some of the areas where there was
CL transmission it was possible to relate the deforestation to the
incidence of the disease. The very high deforestation rates can
represent the disappearance, from the beginning of the study
period, of remnants related to the disease. In some areas, it was
possible to identify deforested remnants that could have
influenced the appearance of the disease, and which can be
observed in Central region. In the Clippings of this region (D,
E, F, M, N), the incidence of the disease could have been
affected not only as a function of the high indices found for
Second and First Deforestation Limits, but also due to the fact
that the relative areas to the Second Deforestation Limit are
near to the First limit, and near to the fragments of permanent
woods. Thus, the relative areas of the Second Deforestatiqn
Limit should be acting as indicators that they would be
composing, with the First Deforestation Limit areas associated
to them, a wood area in 1992 which would have been
deforested (Aparicio 2001).
According to these analyses, it could be possible to consider
four possibilities to indicate transmission profile in the studied
cases: 1) the transmitters became adapted to the domestic
environment and/or the CL reservoirs may be circulating
between woods and dwellings; (2) the mosquito is getting the
houses through sufficiently dense vegetation spread around of
the wood borders; (3) the remnants that could be considered the
habitats of the vectors would have been deforested; (4) the
person who got sick frequented the woods at night when caught
CL.
The first possibility seems to be feasible, once it explains the
cases that were more than 250 meters distant from forest
remnants, and the cases that the deforestation did not
collaborate for CL Incidence as well. If the complete
domestication has not occurred yet, a transitory process,
suggested by the second possibility, could be occurring. In this
case, the mosquitoes could be reaching the human dwellings
since the NDVI values, registered around the remnants, was
elevated.
The third hypothesis is also valid for the C/ippings D, E, and N,
whose distances from houses to the border of the remnants are
respectively of 276, 340 and 260 meters, and where the
association with the Second and the First Deforestation Limit is
observed. Finally, «the last hypothesis seems to be an unviable
confirmation, since it involves personal information, such as if
the sick person has been frequented or not in the woods or in its
proximities during night.
The analysis carried out indicates that three types of
transmission may be occurring in that region: (i) an intra-forest
transmission in areas where a disease focus was found 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 could flight and (iii) transmission in human dwellings.
possibly caused by a mosquito domestication process, in which
the CL transmitters could develop its complete cycle in the
houses neighborhood and where it could be possible to the CL
reservoir circulate from remnant to house.
5— REFERENCES
Aparicio, C., 2001. Utilizacáo de Geoprocessamento e
Sensoriamento Remoto Orbital para análise espacial de
paisagem com incidéncia de Leishmaniose Tegumentar
Americana. [MSc. Dissertation]. Sàáo Paulo, Instituto de
Biociéncias , USP.
Beck, L.R., Lobitz, B.M., Wood, B.L., 2000. Remote Sensing
and Human Health: New Sensors and New Opportunities.
Emerging Infectious Diseases, 6(3):217-226.
Clarke, KC, McLafferty, S.L., Tempalski, B.J., 1996. On
Epidemiology and Geographic Information Systems: a Review
and Discussion of Future Directions. Emerging Infectious
Diseas, 2(2):85-92.
Corte, A.A., Nozawa, M.R., Ferreira, M.C., Pignatti, M.G.,
Rangel, O., Lacerra, S.S., 1996. Aspectos Eco-epidemiológicos
da Leishmaniose Tegumentar Americana no Município de
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