Video: Epidemics and the Environment.
Many of the diseases that cause epidemics in the world today are thought to be triggered by changes of man's interactions with the environment. Three such cases are recent outbreaks of cholera, the plague, and Lyme disease.
In 1991, cholera was detected for the first time in one hundred years in Peru. Cholera is an acute intestinal infection caused by bacteria. It is spread by contaminated water and food (usually raw fish), and through contact with contaminated human feces. It is often associated with algal blooms (plankton), which are influenced by the temperature of the water. The outbreak in Peru was thought to be a result of El Niño, which increases the temperature of the water. .
When cholera occurs in an unprepared community, case-fatality rates may be as high as 50% -- usually because there are no facilities for treatment, or because treatment is given too late. In contrast, a well-organized response in a country with a well established diarrheal disease control program can limit the case-fatality rate to less than 1%. Treatment of cholera simply consists of giving most victims a solution of oral rehydration salts. Severely afflicted individuals may need the help of intravenous fluids. .
Cholera reaches epidemic proportions most often in countries that are poverty stricken. These countries often do not have sanitary living conditions, and thus contaminated water contact may occur on a daily basis. Furthermore, education is lacking in poor countries, and often individuals do not recognize the importance of proper food and water preparation, or hand-washing after using the restroom. .
The second disease that was talked about in the video was an outbreak of the plague in India. Plague is also caused by a bacterial infection. The bacteria are carried by flea infested rodents. The rodents harbor the bacteria and the fleas become infected by biting the rodents.