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Find Points to Treatment for Water-Borne Disease
BY ANDREW VOWLES
Guelph scientists seeking a better way to detect a nasty intestinal bug responsible for occasional illness outbreaks in Canada believe they've also uncovered a promising treatment for one of the world's most common water-borne diseases.
An antibody used to detect a parasite that has sickened thousands of people in several parts of Canada over the past decade can also be used to fight off the bug itself, say researchers in the Department of Environmental Biology.
Their paper published this summer in the journal Antonie van Leeuwenhoek describes the first use of recombinant antibodies for blocking infection of human intestinal cells by the single-celled parasite that causes cryptosporidiosis.
Cryptosporidium parvum is transmitted through drinking water contaminated by the feces of infected animals. Proper water and sewage treatment and filtration as well as correct disposal of animal waste normally prevent the disease from spreading, says Prof. Jack Trevors.
In healthy people, the parasite causes severe diarrhea, abdominal cramping and fever for a week or two. In people who are very young, very old or immune-compromised, the symptoms may be more severe and chronic and may cause death.
Thousands of people were sickened in outbreaks in North Battleford, Sask., in 2001, in Milwaukee in 1993 and in Kelowna, B.C., in 1996. Another 1996 outbreak in Collingwood, Ont., led health authorities to make cryptosporidiosis a reportable disease.
“Every few years, a microbiology problem pops up,” says Trevors, referring to listeriosis and E. coli contamination.
No effective therapy exists for cryptosporidiosis. Patients are told to drink lots of fluids and may be prescribed anti-diarrheal drugs.
Now the Guelph researchers have found that specially engineered recombinant antibodies used to detect the parasite may also prevent the bug from physically binding to human intestinal cells. (Other researchers have used monoclonal antibodies as so-called “magic bullets” in efforts to target other diseases.)
Prof. Hung Lee hopes scientists will use the U of G work to develop a treatment based on using antibodies. He thinks the model might also help in fighting other pathogens.
“Potentially we could use this new approach to address other intestinal infections.”
The research team, which also included Prof. Chris Hall and former graduate students Nicholas Pokorny and Jeanine Boulter-Bitzer, used a tissue culture model system with mammalian intestinal cells. Now continuing their studies, the Guelph researchers hope to learn more about how the antibody binds to the parasite.
They started working on detection methods in 1992. Trevors and Lee served on a provincial Cryptosporidium task force and have previously published work on detecting the parasite in water samples.
Their research was supported by the Canadian Water Network, the Natural Sciences and Engineering Research Council, the Ontario Ministry of Agriculture, Food and Rural Affairs, and the Ontario Ministry of the Environment.