PORTLAND, Maine — Wildlife officials are boosting a program to vaccinate raccoons in the wild in an effort prevent the spread of rabies in Maine and northward into Canada.

About 351,000 oral rabies vaccination baits are going to be distributed over a 2,400-square-mile area in northeastern Maine between Aug. 3 and 7, said Emily Spencer, of the Maine Center for Disease Control and Prevention. That compares to 125,000 doses over a 900-square mile area last year.

One of the reasons for the program’s expansion is to prevent the northern spread of raccoon-variant rabies that has been found north of the border in parts of Canada where rabies has been absent for a couple of decades, said Dr. Michele Walsh, Maine state veterinarian.

But the program also benefits Maine, where there already have been 30 cases this year of animal rabies in 15 of Maine’s 16 counties, she said.

Those rabies cases include several that made the news including a woman bitten by a rabid fox on her porch in Monmouth and man who battled a crazed fox in Topsham. In another case, a jogger was attacked by a rabid raccoon that she killed with her bare hands in Hope.

The Wildlife Services program within the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service began the vaccination program in 2003. The program is part of an effort from the Canadian border to Alabama to prevent raccoon rabies from moving into new areas.

There has been an overall decrease in rabies in places like New England, where the oral vaccinations have been distributed to wildlife, said R. Andre Bell, a USDA spokesman.

“For example, through the use of (vaccinations), raccoon rabies has essentially been eliminated from peninsular Cape Cod, Massachusetts, in recent years,” he said.

The bait is coated in fishmeal to lure raccoons and is distributed on the ground in populated areas and by air in rural forested areas. The vaccine is harmless to humans and has been tested on more than 60 species of animals including dogs and cats, officials say.