Practical Manual - Malareo

Practical 7 Mapping Malaria
Outline
Introduction
Managing Disease Data
Incidence vs Prevalence
Thematic Mapping of Prevalence
Interpolation of Prevalence
Introduction
Malaria is a vector borne disease, and is one of the largest killers in Africa. It is carried by the anopheles
mosquito which is mobile. While their lifespan is limited and their flight ranges limited the sheer number
of mosquitoes make a significant impact. While mosquitoes feed primarily on nectar, they require the
iron and protein from blood in order to procreate. The Female transmits the malaria virus when she
inserts her proboscis through the skin and injects an anti-coagulant into the victim to allow her to suck
blood from the bite site.
In order to target and combat Malaria, one needs to identify where the disease is located. The
distribution of Malaria changes with time, primarily due to the presence or absence of mosquitoes.
Hence in winter (Drier months) there is less malaria due to fewer mosquitoes. Therefore to adequately
map the disease an understanding of the presence of the vector is required.
The most common means of identifying where the highest prevalence of malaria is located is obtained
from medical records where cases of malaria are treated. This can locate where the case was
contracted, giving a general area where the disease is commonly found GIS is a useful means of mapping
the presence and absence of a disease.
The study of diseases is known as epidemiology. There are numerous methods of determining risk and
distribution of disease You will look at a number of statistically based methods to show where malaria is
located.
John Snow is widely regarded as the father of Epidemiology, when he used the presence of cholera
cases to pinpoint the source of the infection in London, tying it to dirty water from a pump.
In essence you will be undertaking a similar exercise.
QGIS for Malaria Page 56