Contaminated drinking water is especially dangerous to humans because of the many diseases that it often transmits. These diseases fall into three major categories: bacterial (caused by bacteria in water), viral (caused by viruses in water), and parasitic (caused by a parasitic protozoa or worm in water).
The bacterial diseases that can result from polluted water include typhoid, cholera, bacterial dysentery, and enteritis. Typhoid resides in the bacterium Salmonella typhi, and it is often fatal if untreated. The symptoms and effects of typhoid include diarrhea, severe vomiting, an enlarged spleen, and an inflamed intestine. Another bacterial disease, cholera, is caused by the bacterium Vibrio cholerae. Its symptoms consist of diarrhea, severe vomiting, and dehydration, and, like typhoid, it is often fatal if left untreated. Bacterial dysentery is rarely fatal except in infants, and its major symptom include diarrhea, abdominal pain, and cramps. Bacterial dysentery results from exposure to the bacterium Shigella dysenteriae. The final bacterial disease is enteritis, which is caused by the bacterium Clostridium perfringens. It is characterized by severe stomach pain, nausea, loss of appetite, and vomiting, and is rarely fatal.
Hepatitis A (also known as infectious hepatitis) is a major viral disease that can be transmitted through contaminated drinking water. The Hepatitis A virus is associated with the following effects: fever, severe headache, loss of appetite, abdominal pain, muscle ache, and inflammation of the liver. It is rarely fatal but may cause permanent liver damage if untreated. Polio, caused by the poliovirus, entails a sore throat, fever, diarrhea, and muscle aches, and may eventually lead to muscle paralysis.
The remaining water-borne diseases are transmitted by parasites. Ameobic dysentery is caused by the parasitic amoeba Entamoeba histolytica, and its symptoms include severe diarrhea, abdominal pain, headache, chills, and fever. It is more serious than bacterial dysentery and may result in death in not treated. Giardiasis is another disease caused by a parasitic protozoon, and it usually results in diarrhea, abdominal cramps, belching, and fatigue. The Ancylostoma worm transmits the disease ancylostomiasis, which results in lung irritation, coughing, and severe anemia. Finally, the Schistosoma worm carries schistosomiasis, a tropical disease whose symptoms include diarrhea, urinal bleeding, and abdominal pain.Thinkquest Team "Fish," March 2005, Disclaimer and copyright information