CBC News Online | June 23, 2004
In May, 2001, residents of North Battleford, Saskatchewan were ordered to boil their water. Authorities believed a parasite had contaminated the city's drinking water. Thousands of people eventually became ill.
Here's a look at cryptosporidium, the parasite at the centre of the story.
Cryptosporidium is a microscopic, single-cell parasite that's about 20 times smaller than the width of a human hair. In water it lives in a round egg called an "oocyst" that is highly resistant to cold, moist conditions.
Because of the oocyst, cryptosporidium can survive in water for months, which
means people who drink water contaminated with the parasite can still get sick
months after the parasite first entered the water source.
HOW IT IS SPREAD
Health authorities believe most contamination occurs when water is exposed to cattle feces containing cryptosporidium. However, people and other animals can also spread the parasite.
People can spread cryptosporidium by accidentally swallowing something that has come into contact with the contaminated feces of an animal or another person. Examples include eating unwashed fruits and vegetables that were sprayed with contaminated manure, and touching surfaces such as bathroom fixtures and diaper pails contaminated with feces from an infected person.
Water filtration at treatment facilities is usually enough to keep cryptosporidium out of drinking water. But the parasite is resistant to chlorination, which is the only treatment some municipalities give their water. At home, people can boil their water to kill the parasite.
The parasite causes an illness called "cryptosporidiosis." The main symptoms are diarrhea, abdominal cramps, upset stomach, nausea and headaches.
No drugs have been approved to treat cryptosporidiosis. Luckily, however, in otherwise healthy people the parasite usually disappears in two weeks to a month. There are also drugs and therapy available to treat diarrhea if it becomes severe.
CAN IT KILL?
Yes. People with weak immune systems are vulnerable, such as the elderly and people with diseases like AIDS and cancer.
In the summer of 1996, cryptosporidium made an estimated 2,000 people sick in Cranbrook, B.C. Weeks later, an outbreak hit Kelowna, B.C. where 10,000 to 15,000 people got sick.
But the outbreak in Milwaukee, Wisconsin in 1993 was far worse. About 100 people died, mostly the elderly and patients with AIDS or cancer, and about 400,000 more got sick.