The World Health Organisation estimates that 80% of all sickness and diseases are due to inadequate water supplies and poor sanitation. The earth has all the water it needs to supply its 6.3 billion inhabitants with clean water. The problem is that water is not evenly distributed.

Ninety seven percent is salty and can be found in oceans. The remainder, a 2.5%, is freshwater, accessible from rivers, lakes, and reservoirs and locked in the ice caps of Antarctica and Greenland, and as groundwater in the lithosphere.

So,in the face of abundance, why are so many people affected by waterborne illnesses from the oceans and associated with vibrios,including cholera? Cholera epidemics caused by Vibrio cholerae O1 occur regularly in Bangladesh and India and sporadically in many parts of the world. In 1993, a total of 296,206 new cases of cholera were reported in South America after about a century, involving more than 15 countries. The outbreaks of cholera that have occurred during the past decade originated in coastal areas.

Tight linkages of zooplankton and V. cholerae indicates that remote sensing is useful in tracking V. cholerae associated with plankton plumes emanating from major rivers where cholera is known to be endemic. Indeed, V. cholerae attaches to plankton in the aquatic environment, providing the vehicle for dispersal. Phytoplankton also provide the main food source for zooplankton. Although V. cholerae cannot be detected by remote sensing techniques, remote sensing has been used successfully to quantify phytoplankton concentrations in the open oceans.