Biology Reference
In-Depth Information
Additionally, controlling stray dogs and providing insecticide-treated col-
lars can help reduce the dog reservoir and associated cases of visceral leish-
maniasis. However, observing or inferring animal reservoirs and habitats
from satellites is difficult. Instead, disease prevalence has been found to be
statistically related to precipitation, temperature, vegetation, and elevation.
These remotely sensed parameters have been used to estimate climate-based
risks for visceral leishmaniasis transmission (Nieto et al. 2006).
3.2.7 Cholera
Cholera is caused by the bacteria
Vibrio cholerae
. The disease was believed
endemic to the Indian subcontinent as early as 500 B.C. before it spread to
other parts of the world. Through proper filtering and chlorination of water
supplies, cholera largely has disappeared in developed countries, but it is still
a significant problem in the developing world. The disease may spread quickly
if it is not managed properly through sterilization and decontamination. Oral
rehydration is the predominant and most effective treatment. Without it, an
infected person may die in just a few hours after symptoms appear.
C h o l e r a - c au s i n g b a c t e r i a h ave b e e n s h o w n t o b e n at u r a l ly at t a c h e d t o pl a n k-
tonic copepods (Hug et al. 1983). Planktonic copepods are groups of small
crustaceans, which are food but also parasitic to many kinds of marine mam-
mals and invertebrates. In some coastal areas, during a planktonic bloom, a
glass of untreated or unfiltered water may contain several copepods. Because
planktonic copepods graze on phytoplankton and transport carbon to ocean
depths, planktonic copepods play a necessary role in the ocean's carbon cycle
and are an integral component of the Earth's ecosystem. As a result, it will
not be possible to eradicate cholera by eliminating copepods. Instead, the
only ways to protect against this disease may be improved living standards
and sanitation practices, proper treatment of drinking water, improved pub-
lic health surveillance and response, and early warning and vaccination.
The environmental determinants associated with cholera are those that
promote the growth of planktonic copepods, including sea surface tempera-
ture, ocean height, and plankton blooms (Colewell 2004). All these parame-
ters, along with coastal brackish and estuarine ecosystems where the bacteria
may be present, can be remotely sensed. In addition, remote sensing can also
monitor El Niño events, which affect weather patterns and ocean tempera-
ture for a significant portion of the world. The prediction of El Niño is a topic
actively studied by climate researchers.
3.2.8 Schistosomiasis
Schistosomiasis is a parasitic disease transmitted by five species of
Schistosoma
; one species causes urinary schistosomiasis, and the other four
cause intestinal schistosomiasis. Schistosomiasis is one of the 14 neglected
tropical diseases, tends to affect the poorest communities of the world, and is
