TITLE:
Mapping of Freshwater Snails’ Habitat—A Source of Transmitting Bilharzia in Mwea Sub-County, Kenya
AUTHORS:
Mark Kipkurwa Boitt, Mungai Kaara Suleiman
KEYWORDS:
Area Under Operating Curve (AUC), Species Distribution Models, Maximum Entropy (MaxEnt), Land Surface Temperatures, Geographic Information Systems, Remote Sensing, Land Use Land Cover
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.9 No.10,
October
27,
2021
ABSTRACT: Bilharzia is vector-borne disease carried by a parasite that is hosted by
fresh water snails. The distribution of the disease is concurrent with the
existence of the freshwater snails and is dependent on certain suitable environmental conditions. It is difficult
to identify the specific habitats of the snails as they are often inaccessible
on the ground, the snails also migrate by means of flowing water, making it
difficult to keep a track of the freshwater snails’ habitat. This paper aimed
at using GIS, Remote Sensing and Species Distribution Modelling techniques to
model the suitable habitats for the freshwater snails and to prove that the
snails migrate when there are sudden changes in water levels whilst showing the
population at risk of bilharzia. The SDM used is the Maximum Entropy (MAXENT)
for its ability to make right predictions even with small presence sites. The
AUC value of the model was 0.951. The research results showed that the
environmental variables; brightness Index, elevation, temperatures were
negatively correlated with the snails’ presence while the wetness index, MSAVI,
greenness index and soil pH were positively correlated. The snails are observed
to favor clay soils of the montmorillonite type and the crop-lands land cover.
Areas consistently submerged by water especially after flooding are shown to be
the most suitable areas where snails migrate by means of river or canal water. The
research proves that Mwea is not the source habitat of the freshwater snails.
The neighboring sub-counties within Kirinyaga County should be investigated
using such models as a likely source-habitat of the freshwater snails. Destroying
the source habitats will lead to complete eradication of the freshwater snails
within Mwea.