WEATHER | DISEASE | WATER | HUNGER | AIR POLLUTION | ALLERGIES 
Over 400,000 people were infected with cryptosporidium—a gastrointestinal illness—after the Mississippi River flooded Milwaukee's public water supply in 1993. Hurricane Mitch in 1998 dumped six feet of rain on Honduras in three days and left epidemics of malaria, dengue fever and cholera along with more than 11,000 dead. In Venezuela in 1999 severe rains led to outbreaks of brain infections called encephalitis, and landslides killed tens of thousands.
Water quality is jeopardized by increased heavy rainfalls, especially if preceded by drought, as surface waters became polluted by runoff carrying human and animal wastes, pesticides, fertilizers, and other pollutants.
In the past, outbreaks of water-borne diseases, such as Cryptosporidium and Escherichia coli, have been linked to heavy rainfall events. An analysis of 548 gastrointestinal outbreaks that occurred in the United States between 1948 and 1994 showed that 68 percent of cases were preceded by very heavy rainfall. Threats to water quality from increased precipitation will be compounded by rising temperatures, which promote the growth of disease-causing bacteria.
In the ocean, the combination of rising surface water temperatures and increased nutrient loading from rivers carrying agricultural runoff may contribute to increased harmful blooms of algal species producing biotoxins. The consumption of fish and shellfish contaminated with these toxins can result in neurological damage, respiratory irritation, skin irritations, and gastrointestinal illness.
Water quantity may also become an issue as a result of global warming. Droughts, decreased winter snow-packs, earlier snowmelt, and a shift to less frequent, but more intense precipitation events could all put a strain on freshwater resources. As water supplies decline, concentrations of human waste, animal waste, and other pollutants increase while stagnant waters provide breeding ground for disease vectors. Poor, developing nations in southern and West Africa and in the Middle East are at particular risk to increased water stress and may experience a rise in the incidence of water-related diseases as people are forced to rely on increasingly contaminated sources of fresh water for all of their daily needs—drinking, cooking, bathing, and irrigation.
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