A Brief History of Rabies in Ontario

Rabies is an infectious and contagious disease of the central nervous system. It has been known since the ancient days of 2300 B.C. This lethal virus still exists in almost all parts of the world.


Once infected, and left untreated, this disease is usually fatal. The rabies virus is concentrated in the saliva, mucous membranes and central nervous tissue of a rabid animal. Only humans, and other mammals, can become infected through a cut or scratch from an animal with rabies, or if the rabies virus comes in contact with the moist tissues of the mouth, nose or eyes.


There are two ways that rabies symptoms appear, dumb and furious. Both can cause abnormal behavior. Immediately prior to death, animals with furious rabies will appear to be ‘mad’: frothing at the mouth and biting anything that gets in their way. They may show extreme excitement and attack stationary things or animals. Bouts of furious rabies usually alternate with periods of depression.


In dumb rabies, there is no ‘mad’ period. With dumb rabies, paralysis, usually of the lower jaw, and a drooping head are the first signs of the disease. The paralysis quickly spreads to limbs and vital organs and death quickly follows. Animals with dumb rabies may become depressed and retreat to isolated places. Some may appear ‘tame’, having no fear of humans.


At one time, Ontario was known as the ‘Rabies Capital of North America’ due to the high number of rabid animals reported. Since 1992, the number of rabies cases has been reduced by 98%. In Ontario, rabies control programs focus on terrestrial rabies (Arctic fox strain and mid-Atlantic raccoon strain) while education programs focus on the various bat strains of rabies.


Arctic Fox Strain


This strain of rabies invaded southern Ontario, between 1954 and 1959, from northern Ontario and Quebec. In northern Ontario, the disease disappeared in 1972 but reappeared in 1989. It was eliminated from southeastern Ontario, but still persists in low numbers in certain areas across southwestern Ontario.


Raccoon Strain


This strain of rabies (mid-Atlantic) was first reported in Florida in 1947, remained in the southeastern coastal parts of the USA until 1977, and then began to rapidly spread northward. It entered Ontario in July 1999. It was first discovered in a juvenile raccoon found dead in a dog kennel, just northwest of Prescott. Since the first case, 132 cases in total have been reported within this general area of Ontario. The last reported case of raccoon rabies in Ontario occurred in September 2005.


Bat Strain


These strains of rabies were first diagnosed in Ontario in 1961. There are eight species of bats in Ontario, all of which have their own strain of the disease, but the most common are Little Brown bat, Big Brown bat, and Silver-haired bat. Although bats are the most widely distributed mammal, less than 2% of bats submitted for testing have rabies (2% of all bats acting strangely, dead, or have possibly bitten a human or pet). In the overall population, this percentage would be much lower.


Role of the Ministry of Natural Resources in rabies management


The Ministry of Natural Resources is responsible for managing and researching rabies in wildlife. In the past, they have focused on three means of controlling rabies: aerial vaccine baiting and TVR (trap-vaccinate-release) and controlling the disease at the point of infection when a new case is confirmed. Presently, the primary control program is aerial vaccine baiting, which consists of dropping specially prepared vaccine baits from airplanes or helicopters in areas that have a high incidence of terrestrial rabies. The MNR is also a leading agency in the research of this deadly disease. From studies of wildlife movement and genetics to vaccine and bait development, the MNR ensures that its programs are based on the best science available.



Microscope from iStockPhoto.com