The vaccine against Entamoeba histolytica is a breakthrough, said lead scientist Kris Chadee, because currently "there are no vaccines for any parasite ... we have the first animal tested protective vaccine."
The research is published in the October issue of science journal Infection and Immunity, and is available online.
The vaccine is sprayed into the nose -- a novel, non-invasive and very promising method -- and prompts the body's immune system to arm itself against the parasite, said Chadee.
Entamoeba histolytica is the only amoeba that kills humans. It affects people with poor immune systems causing bloody diarrhea, dehydration and in some cases abscesses on the liver.
It spreads through stools, in contaminated water and food and is found in slums in most developing countries, especially Mexico, Bangladesh, India and southern Africa. It is brought to North America and Europe by travellers and immigrants, said Chadee.
"A lot of kids are being infected and dying on an annual basis," he said, adding that treatment for the disease with a drug called Flagel is both expensive and not tolerated by all patients.
Chadee and his team at the University of Calgary tested their vaccine on gerbils. All those who were vaccinated remained healthy, while the unprotected animals developed abscesses, they said in their report.
The next step, he said, is to test the vaccine on non-human primates. With funding from pharmaceutical companies or a foundation, "we could see clinical trials (in humans) in five years."
Chadee said he would like his vaccine, once its developed, to target the population most at risk, children and poor people in third-world countries.
"That's the problem," he added, "because the pharmaceutical industry in North America and Europe, unless there is a profit margin, tends not to pursue it ... but I'm an optimistic scientist."