New tools devised to detect, kill water parasites
By Jen Ross
There may be fewer boil-your-water warnings and fewer outbreaks of "beaver fever" if two University of Alberta scientists have their way.
Giardia and cryptosporidium are two common and pesky parasites responsible for most of the waterborne parasitic infections in the world. They can cause severe diarrhea, vomiting and dehydration which can be deadly for the young, the sick and the frail.
Last year, 15,000 people became sick from a cryptosporidiosis outbreak in Kelowna, B.C.
Locally, there were 138 reported cases of giardiasis -- commonly known as beaver fever -- and Capital Health issued two advisories to boil water last spring after Aqualta found the organisms in Edmonton's water supply.
The parasites usually don't make it into tap water, but when they do, they're tough to spot and among the hardest to get rid of by conventional disinfection.
That's why U of A biology professor Mike Belosevic and civil engineering professor Gordon Finch have spent the past nine years devising new ways to detect and remove these parasites before they get to the faucet.
The research team has beat out dozens of world-renowned scientists for over $3 million in research grants since 1989 from the U.S. Environmental Protection Agency and the American Waterworks Research Foundation.
There are currently few accurate ways to detect parasites in drinking water, and no way to tell whether they're dead or alive.
"Now if public health sees a parasite in drinking water, they get worried and issue an alert," says Belosevic. "But if it's dead, who cares? It can't make you sick. You need to know if they're living or not to know if they pose a threat, but they don't have the tools to know that yet."
Belosevic has developed an automated staining technique and uses it with a machine called a flow cytometer to spot parasites and read their vitals.
He pours nucleic acid dyes into a water sample, staining the parasites. Next, he passes laser beams through the water, leaving the organisms aglow in fluorescent colours. A living one might show up on a computer screen as a bright green dot amid a sea of dead red ones.
"Before this, they were tricky little devils to look for," says Belosevic's research partner Finch, "like proverbial needles in a haystack."
The filtration in most purification plants today will usually remove parasites, but if they get past the filters, chlorine won't kill cryptosporidium.
Enter Finch. He's been looking into using ozone or chlorine dioxide gas disolved in water as a third line of defence. These kill both parasites and may be able to wipe out a multitude of other infectious organisms science has yet to discover.
The U of A team is two years away from completing its work and publishing the findings, but the research is already being applied around the world.
Last year, Milwaukee water utilities used Finch's data when the city forced water purification plants to install ozone to kill parasites. The American city got tough after 400,000 people came down with cryptosporidiosis in a 1993 outbreak in its water supply.
The technology isn't cheap. Belosevic's flow cytometer costs $150,000 and it would cost millions of dollars to add ozone or other disinfectants to the purification process.
Some in the water industry wonder if it's worth it.
"That's the real question: Is this a big enough problem to be paying millions for?" asks Les Gammie, director of quality assurance for Aqualta, which looks after Edmonton's water quality.
It is now figuring out just how much it would cost to equip its plants with parasite-savvy monitors and filters.
"It's not a major health risk," says Gammie of the parasite problem. "It's unpleasant and it costs the economy in terms of workdays lost, but is it worth those health dollars?"
According to Capital Health, there have been no parasitic infections related to tap water reported locally in the past four years.
But Finch says figures on infections may be misleading because most cases go unreported.
"Most people don't go to the doctor when they get diarrhea,"he says. "To detect an outbreak, you need people to go to the doctor, the doctor has to order a stool sample, and he has to happen to look for these particular parasites."
Belosevic says he'll let politicians decide if it's worth picking up the tab.
This is already being done by U.S. regulators. The EPA is pushing a new safe drinking water act that may make parasite monitoring mandatory in water plants. The regulations would likely be applied in Canada because Health Canada mirrors most major EPA decisions.
EPA regulator Ephraim King says the agency will likely adopt zero-tolerance regulations for cryptosporidium in November and tighten filtration standards by year's end.
However, he says it's too early to know if they'll require all water purification plants to install Belosevic's parasite monitors or beef up their disinfection with Finch's techniques.
King says Belosevic's technology is promising, but the EPA will have to make sure it works on all U.S. waters, consider the cost, and see how easy it is to use.
GIARDIA AND CRYPTOSPORIDIUM
* WHERE THEY COME FROM: contaminated animal or human feces.
* SYMPTOMS: diarrhea, vomiting, dehydration, fever, abdominal pain, bloating.
* ARE THEY DEADLY? Usually not, but some young children, seniors and people with weak immune systems have died from them.
* REPORTED CASES OF GIARDIASIS IN EDMONTON IN 1997: 138.
* REPORTED CASES OF CRYPTOSPORIDIOSIS: 4 (but it is still not a reportable disease).
* HOW YOU GET INFECTED: drinking lake water or tap water when travelling.
* MAJOR LOCAL OUTBREAK: 1983 when there were 895 cases of giardiasis.
* HOW TO KILL THEM: boiling water. Water purification plants can remove them by filtration, but chlorine does not kill cryptosporidium. Once you get sick, giardiasis is treatable by antibiotics, but there are no drugs to treat cryptosporidiosis.