Is climate change causing insect-borne diseases in cattle?

By Dr. Robert Tremblay

Europe is gripped not only by a financial crisis but also by substantial changes in its animal health situation.

Like Canada, most of Europe has a high standard of farm animal health. Starting several years ago, this began to change. We all heard about the BSE and the Foot and Mouth Disease outbreaks. Less newsworthy but equally important has been the spread of the disease Bluetongue across most of the countries of northern Europe. Bluetongue is caused by a virus but is spread by insects. Many believe that climate change made it possible for Bluetongue, which used to be limited to southern Europe, to move into northern Europe and to spread right across the northern countries. They believe that climate change made possible the spread of the insects that spread the virus.

In the last few months another new disease has been spreading across Europe. This disease is caused by a virus called Schmallenberg virus. It causes a range of signs including fever, diarrhea and a drop in milk production. We don’t know a great deal about this virus, including where exactly it came from, but it does belong to a group of other viruses that are spread by insects. Obviously since we don’t know much about Schmallenberg virus, we can’t speculate that climate change played any sort of role in its spread across the countries of northern Europe.

We do not have many cattle diseases in Canada that are spread by insects. One we could get, though, is anaplasmosis. Anaplasmosis is a blood disease of cattle and some other species. It is spread by ticks. Anaplasmosis is exotic to Canada and is a reportable disease here. If an animal owner or veterinarian suspected that an animal had anaplasmosis, he or she are compelled to notify the CFIA.

A few years ago, I heard a veterinarian from the U.S. Midwest describe their losing battle with anaplasmosis. He related that their failure to control the spread of the disease was related to the ever expanding range of the ticks that spread the infection. If you can’t contain infected ticks, it is pretty difficult to control the spread of the disease in cattle. Some forms of anaplasmosis now occur in states adjacent to the Canadian border. It is likely just a matter of time before it arrives here . . . courtesy of climate change?