MONTREAL - Quebec wildlife officials say they've contained a stubborn rabies outbreak emanating from the United States, trapping it in an area around a small town along the Quebec-Vermont border.

One phase of a ground operation to trap and kill raccoons and skunks was set to end Wednesday but conservation officers will resume the effort next month in the area along the southeastern border with Vermont.

They will also drop more cookies laced with oral rabies vaccine around St-Armand, near the Quebec-Vermont border. Officers in Vermont are running a similar campaign.

Quebec natural resources spokesman Pierre Canac-Marquis says infected animals from the United States are spreading rabies into Quebec. With 50 cases of raccoon and skunk rabies reported in the first six months of 2007 in Vermont, Quebec knew it had an outbreak heading its way.

"It's really the first time we've had this kind of intense outbreak,'' Canac-Marquis said.

Wildlife officials have 700 new samples to analyze, but the ratio of animals infected has considerably improved, he said.

At the height of the outbreak, conservation officers found one-in-15 raccoons on the Quebec side of the border area had contracted the disease. Those numbers have improved to one out of 45, according to Canac-Marquis.

"So far, the results we are getting is that we were quite successful in containing the outbreak,'' he said.

Rabies, which can be fatal if left untreated in humans, attacks the nervous system and is spread from animal to animal through saliva.

No humans have been infected in the latest outbreak, said Dr. Jocelyne Sauve, public health director for the affected region.

Thousands of traps have been set in the area 85 kilometres southeast of Montreal. Some animals have been euthanized as a precaution.

The main objective is to create a barrier or eradicate the outbreak altogether so it doesn't enter more heavily populated areas, including Montreal.

Canac-Marquis says the threat to the Montreal area is very real. American studies show that the virus can spread up to 40 kilometres in a single year.

Montreal officials estimate there are as many as 50 raccoons per square kilometre on Mount Royal, the wooded park in the heart of the city. With a large number of domestic animals, officials say an outbreak in the city could be a disaster.

Quebec's first case of raccoon rabies was reported in 2006 but it could take years of operations to really get a handle on the virus, Canac-Marquis said. Quebec is following in the footsteps of Ontario, where a raccoon rabies outbreak in 1999 was stopped by 2006.

It is believed the Ontario virus came north via New York State. Advanced testing this year showed no sign of rabies infections in the area.

Generally, once rabies is established in an area, it can be very hard to get rid off, said Dennis Slate, national rabies co-ordinator with the United States Department of Agriculture.

"When you're dealing with rabies, it's hard to say how long it will take,'' Slate said. "Right through the winter, we found rabid animals (in Vermont). That was pretty indicative of a hot rabies outbreak.''

The last reported case of human rabies in Quebec was in October 2000, when a 9-year-old boy died after coming into contact with a rabid bat.