Cholera is an acute, diarrheal illness caused by infection of the intestine with the bacterium Vibrio cholerae. The infection can be mild or without symptoms, but sometimes it can be severe. Approximately one in 20 infected persons has severe disease characterized by profuse watery diarrhea, vomiting, and leg cramps. In these persons, rapid loss of body fluids leads to dehydration and shock. Without treatment, death can occur within hours.

Cryptosporidiosis is a diarrheal disease caused by microscopic parasites of the genus Cryptosporidium. Once an animal or person is infected, the parasite lives in the intestine and passes in the stool. The parasite is protected by an outer shell that allows it to survive outside the body for long periods of time and makes it very resistant to chlorine-based disinfectants. Both the disease and the parasite are commonly known as "crypto." This parasitic infection can result in severe diarrhea and can also produce nausea, vomiting, weight loss, and dehydration.

Cyclospora infects the small intestine (bowel) and usually causes watery diarrhea, with frequent bowel movements. Other symptoms can include loss of appetite, substantial loss of weight, bloating, increased gas, stomach cramps, nausea, vomiting, muscle aches, low-grade fever, and fatigue. Some people who are infected with Cyclospora do not have any symptoms.

Giardiasis is a diarrheal illness caused by a one-celled, microscopic parasite, Giardia intestinalis (also known as Giardia lamblia). Once an animal or person has been infected with Giardia intestinalis, the parasite lives in the intestine and is passed in the stool. Because the parasite is protected by an outer shell, it can survive outside the body and in the environment for long periods of time. During the past two decades, Giardia infection has become recognized as one of the most common causes of waterborne disease in humans.

Guinea worm disease is a parasitic worm infection. People get infected when they drink standing water containing a tiny water flea that is infected with the larvae of the Guinea worm. Inside the human body, the larvae mature, and the threadlike parasitic worm grows and matures up to three-feet long, and as wide as a paper clip wire. After a year, the worm emerges through a painful blister in the skin, usually in the lower limbs, causing long-term suffering and sometimes crippling after-effects. The worms cause swelling and painful, burning blisters.

Hepatitis A is a viral infection of the liver and is spread by ingesting contaminated food or water. The virus is highly contagious and may be passed from person to person, and unlike many other viruses, it can survive for a long time at room temperature. Symptoms include tiredness, loss of appetite, nausea, vomiting, or stomach ache, dark urine, and jaundice.

Legionellosis is a bacterial disease that results in pneumonia. Legionellosis can be a mild respiratory illness, or it can be severe enough to cause death. People contract legionellosis when they inhale water mist containing the bacteria. The early symptoms of legionellosis may be flu-like with muscle aches, headache, tiredness and dry cough, chills, diarrhea, and a high fever, commonly reaching 102-105 degrees.

Leptospirosis is caused by bacteria of the genus Leptospira. Humans become infected through contact with water, food, or soil containing urine from infected animals. In humans, it causes a wide range of symptoms, and some infected persons may have no symptoms at all. Symptoms of leptospirosis include high fever, severe headache, chills, muscle aches, and vomiting, and may include jaundice (yellow skin and eyes), red eyes, abdominal pain, diarrhea, or a rash. If the disease is not treated, the patient could develop kidney damage, meningitis, liver failure, and respiratory distress.

Schistosomiasis is a disease caused by parasitic worms, also known as bilharzia Water becomes contaminated by worm eggs when infected people urinate or defecate in the water. Schistosoma parasites penetrate the skin of persons who are wading, swimming, bathing, or washing in contaminated water. Within several weeks, worms grow inside the blood vessels of the body and produce eggs. For people who are repeatedly infected for many years, the parasite can damage the liver, intestines, lungs, and bladder.

Typhoid Fever is a sustained fever as high as 103° to 104° F (39° to 40° C). Those impacted may also feel weak, or have stomach pains, headache, or loss of appetite. In some cases, patients have a rash of flat, rose-colored spots. Persons given antibiotics usually begin to feel better within 2 to 3 days, and deaths rarely occur. However, persons who do not get treatment may continue to have fever for weeks or months, and as many as 20 percent may die from complications of the infection.