Three more confirmed cases of raccoon rabies have been discovered in Hamilton, as the deadly infectious disease claws its way back into Ontario after a decade away.

Now, the province is expanding the area for aerial drop zones of rabies vaccine in an effort to curb the disease's spread and planning a longer term strategy to eradicate it in the area.

"Today, the Canadian Food Inspection Agency confirmed to the Ministry of Natural Resources and Forestry that three of the 14 dead raccoons picked up by Animal Services since Friday have also tested positive for Raccoon Strain Rabies bringing the total confirmed cases to four," the city said in a news release.

This comes just days after the first rabid raccoon found in the province in 10 years got into a fight with two dogs in the back of city animal control van.

"These additional cases signal that Raccoon Strain Rabies is circulating in the raccoon population in Hamilton," the city said.

These cases are the first of the raccoon rabies strain found in Ontario since 2005. The fox rabies strain hasn't been detected in Ontario since 2010, while bat rabies remains in small pockets in the province.

Vaccinating by helicopter

Ministry officials were in a helicopter over Stoney Creek Wednesday dropping baited vaccines to the ground below in an effort to curb the spread of the disease.

This was originally intended to be a one and done precautionary measure — but now, there will be ongoing monitoring in the city for at least two years, Associate Medical Officer of Health Jessica Hopkins told CBC News.

The Ministry of Natural Resources and Forestry is also now expanding the geographic scope of the bait drop from the original area between the Red Hill Valley, Mud Street, Fruitland Road, and the lakeshore to include Haldibrook Road, Glancaster/Upper Paradise and Woodburn Road.

"This is of course a concern," Hopkins said, adding that the ministry will also be testing other animals for rabies to discern the "geographic scope" of the issue.

"However, the risk to the general public is low," she said.

Chris Davies, the Ministry of Natural Resources' manager of wildlife research, said that 46,000 bait vaccines will be dropped in the Hamilton area by the end of the week.

The ministry has a stockpile of 500,000 bait packs to draw from in case of an incident like this, Davies said. That's a plus, as it takes about five to six months to make. A second round of vaccine baits will be dropped in the spring and summer, Davies said. By then, the province should have a handle on the spread of the infection.

"This break in the weather can be both good and bad," Davies said. "It's bad in that the animals are still active. But it's good because we can still get out and do this baiting."

Protect your pets

The city recommends these measures to minimize risk for residents and pets:

Report potential exposures due to animal bites or scratches to public health by calling the city at 905-546-2489.

Wash wounds with soap and water and seek medical attention if you believe you were bitten by or in contact with a sick raccoon.

If you see other sick raccoons, skunks or other wildlife, report it to the city.

It is important to vaccinate your pets against rabies, and to keep vaccines up to date.

Supervise your pets and avoid any contact with wild animals.

Do not feed or handle and never transport or relocate wildlife.

Hamilton does have rabies vaccine on hand to treat any possible infections, Hopkins said, adding that Public Health does give those shots out each year for precautionary reasons.

The Ministry says that the last known case of rabies infection in a human happened back in 1967 in the Ottawa area.

adam.carter@cbc.ca