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| Geographic information system (GIS)-based modeling of an intermediate host snail species’ environmental
requirements using known occurrence records can provide estimates of its spatial distribution. When other data are
lacking, this can be used as a rough spatial prediction of potential snail-borne disease transmission areas. Furthermore,
knowledge of abiotic factors affecting intra-molluscan parasitic development can be used to make “masks” based on
remotely sensed climatic data, and these can in turn be used to refine these predictions. We used data from a recent
freshwater snail survey from Uganda, environmental data and the genetic algorithm for rule-set prediction (GARP) to
map the potential distribution of snail species known to act as intermediate hosts of several human and animal parasites.
The results suggest that large areas of Uganda are suitable habitats for many of these snail species, indicating a
large potential for disease transmission. The lack of parasitological data still makes it difficult to determine the magnitude
of actual disease transmission, but the predicted snail distributions might be used as indicators of potential present
and future risk areas. Some of the predicted snail distribution maps were furthermore combined with temperature
masks delineating suitable temperature regimes of the parasites they host. This revealed the coinciding suitable areas
for snail and parasite, but also areas suitable for host snails, but apparently not for the parasites. Assuming that the
developed models correctly reflect areas suitable for transmission, the applied approach could prove useful for targeting
control interventions. | |
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