Biology Reference
In-Depth Information
early warning techniques for malaria developed by various research groups
for different regions of the world (e.g., Thomson et al. 1996; Hay et al. 1998;
Rogers et al. 2002; Abeku et al. 2004; Teklehaimanot et al. 2004; Omumbo et al.
2004; Thomson et al. 2006). Early warnings of more intense malaria transmis-
sions or possible outbreaks allow public health organizations to implement
countermeasures, such as larval and vector controls, distribution or retreat-
ment of bed nets, and public awareness campaigns, so as to strengthen pub-
lic health support and readiness. While there are usually no estimates done
on how many lives are saved through these initiatives, such techniques can
clearly help reduce human suffering and avert tragedies.
Similar approaches have been applied for the control of other infec-
tious diseases, including a number of the World Health Organization
(WHO)-designated neglected tropical diseases (NTD). As many of the vic-
tims of NTDs are among the world's poorest, it is a very promising prospect
that remote sensing can be a cost-effective approach to help control these
diseases in developing countries.
In this chapter, we will describe the environmental and contextual deter-
minants of a number of the more important infectious diseases, ranging
from those that are more familiar and have afflicted humans since the
ancient times to the more recent ones such as H5N1 avian influenza, which
is still actively present in certain parts of the world. Remote sensing data can
provide information on necessary geophysical parameters. Techniques for
ground cover classification, which can be necessary for identifying ground
cover types and extracting certain environmental and contextual informa-
tion, will be explained. A number of statistical and biological modeling tech-
niques that can utilize remotely sensed geophysical parameters to model
disease risks will also be discussed.
3.2 Environmental Determinants for the
Transmission of Infectious Diseases
Infectious diseases are caused by pathogenic microbial agents such as viruses,
bacteria, protozoa, parasites, and fungi. Diseases are contagious or commu-
nicable if they can be transmitted among humans or transmitted within or
across species. Agents of infection include contaminated objects or media,
as well as vectors that carry pathogens from one host to another. Vectors are
considered to be either mechanical or biological. Mechanical vectors are
those that are not infected by pathogens themselves. Biological vec-
tors are those that do become infected and also play an integral role in a
pathogen's life cycle. The vectors for common infectious diseases are often
arthropods (such as mosquitoes, sand flies, and ticks) or mammals (such as
