Fuzzy expert
systems and GIS for cholera health risk
Cholera is listed
as an internationally quarantinable disease by the International Health
Organization, and it is one of the most researched communicable diseases, yet
it is still wreaking havoc on countries in Southern and Eastern Africa.
Outbreaks in 2000 were traced to the uMhlathuze River in the northern part of
the KwaZulu-Natal Province. Risk factors for cholera outbreaks include a hot
and humid climate and socio-economic factors. The CSIR, Council for Scientific
and Industrial Research, has used GIS tools to assess likely locations for
outbreaks. Their models use the assumption that environmental conditions like
algal blooms trigger Vibrio, the bacteria that cause cholera, growth. If there
is Vibrio in the water, spread of the disease then depends on human access to
safe water. This risk potential model was designed to predict cholera outbreaks
and hopefully prevent them in the future.
The cholera outbreak potential model takes
into account average annual rainfall, mean maximum daily temperature on a
monthly basis and ‘month of first rains’ per pixel (salts from the first rain
run into the river affecting the salinity). Results from the model show long
term cholera outbreak risk. However, results do not show location and time of
the outbreaks. Expanding the model will incorporate remote sensing data to supply
input information for data like phytoplankton levels and the spread of algal
blooms. Field data will need to be taken for data like temperature, daily
rainfall, dissolved oxygen levels, salinity, oxidization, reduction potential, presence
of bacteria, and pH. The model will take into account the weather data around
the time of past cholera outbreaks, and predictions of future outbreaks can be
made. Funding has been given to this project to make remote sensing possible.
Fleming,
Gavin; Merwe, Marna van der; McFerren, Graeme. (2006). Fuzzy expert systems and
GIS for cholera health risk prediction in southern Africa. Science Direct. Retrieved from
It is amazing to see the arc of history from Jon Snow's first spatial analysis applications to cholera in England to today's application. While the technology is more advanced, the basic analysis is the same.
ReplyDeleteThis looks like a very effective study. As you said that it was missing, I think it would be interesting to have times of outbreak represented by points on the map to go along with this. I think that would be helpful data for this cause to have.
ReplyDeleteI agree with Sam, it would have been interesting to how quickly it spread on different paths. It is also incredible to see how far inland it traveled from the original source.
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