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An outbreak of Potomac horse fever (PHF) in Alberta this year has received a fair amount of attention, with stories appearing in the , and on and . Is it because this is an unusually severe outbreak, or has the COVID-19 pandemic changed the way we think and talk about infectious diseases?

• Photo above: An outbreak of Potomac horse fever in Alberta this year is getting more attention than normal. Photo by Todd Korol

Dr. Ashley Whitehead, DVM, associate dean, clinical programs at the ����ɫ�� Faculty of Veterinary Medicine (UCVM) thinks it’s the latter. She sees this change of mindset as a positive shift.

Whitehead has been the go-to subject matter expert for much of the recent media coverage about the outbreak of PHF — an infectious and a potentially fatal disease that causes diarrhea, fever, anorexia, depression, and colic in horses. Whitehead isn’t surprised that this year’s outbreak is getting more attention than in past years, and that’s partly because cases have continued well into the fall.

Wet weather earlier this year created pools of standing water, and was followed by a long, warm fall. Whitehead says this created perfect breeding grounds for the aquatic insects that spread Neorickettsia risticii, the bacteria that causes the disease, when inadvertently ingested by horses drinking or eating.

Owners often shamed as a result of outbreaks

The disease is not uncommon in Alberta, with at least a few cases every year. What is rare, Whitehead says, is people are openly talking about it.

“Animal owners often get shamed in their communities and on social media if they experience an outbreak that could cause risk to other animals,” says Whitehead. “While the outbreak is likely not the owner’s fault, it often causes them to keep the outbreak secret, which causes so much more harm.”

COVID-19 brings new awareness to the importance of disease tracking and communication

COVID-19 has started to change some of the stigma associated with outbreaks, Whitehead says.

“Everyone is tracking numbers to see where things stand," she says." It’s a huge benefit to disease surveillance in animals. People are realizing that it helps to share information. It means owners know the risk to their animals when it comes to certain activities in certain areas and can make better decisions.”

Linda Atkinson, owner-operator of El Caballo Ranch in Millarville, Alta., has long been campaigning for better disease surveillance and communication for the equine community. “If we don’t know in a timely fashion of diseases that are out there, we can’t be prepared for them. We can’t treat them accordingly. We have to know,” she says.

“We have to be informed. This is an initiative that the equine community needs to get behind and support. We currently rely on out-of-country organizations to manage our disease surveillance and communication, but that is starting to change.”

Expansion increases UCVM’s ability to identify and track diseases in Alberta

Earlier this month, the Alberta government announced $3.44 million in federal and provincial funding for UCVM’s .

The new funding allows the DSU to expand and launch a pilot project to begin providing more essential diagnostic services to Alberta’s livestock industry.

The expansion will help industry better treat diseases and conditions in animals, but according to Whitehead, it will also increase the province’s ability to conduct more effective disease surveillance in all species, including horses.

According to Whitehead, there are two forms of surveillance; active and scanning, also known as passive. Active surveillance is a targeted process looking for specific diseases that are known to exist, or that are known to exist in a specific area. The current COVID testing approach in Alberta is a good example of this.

“The problem is if we only look for diseases we know we have, we leave ourselves vulnerable to missing diseases that we didn’t know existed or that we didn’t know we had in the province. And it begs the question; how can you look for a disease that you don’t know exists?”

Dr. Jennifer Davies, DVM, director of the DSU, explains this is where scanning surveillance comes in. “Scanning surveillance happens simply by the act of determining what made an animal sick. It is through scanning surveillance that we discover new and emerging diseases in the region that can negatively impact animal and potentially human health. In my mind it is one of the most important functions of a veterinary diagnostic lab and it is why I am so excited about the expansion of diagnostic services at the DSU.”

Whitehead says this is extremely important for our Alberta horses. “Effective equine disease surveillance is essential to protect the health and well-being of our horses and ensure that we can continue to travel freely with horses not only in Canada but also into the United States. Horses are part of a large industry in Canada when you think about competition, racing, ranch work, and pleasure horses.”

New bacteria detected as a result of heightened awareness

This is what has happened with Alberta’s PHF outbreak. With more owners aware of the outbreak and the disease’s symptoms, more animals are being brought in for treatment and most important, testing.

“We have a lot of horses that come in that we think have Potomac fever,” Whitehead said in an interview with the . “Although the horses respond appropriately to treatment for PHF, they come up negative in tests for the disease. Because of that testing, we know there is the potential that something else is causing the disease.”

Whitehead says a similar bacterium, called Neorickettsia findlayensis, found in horses with symptoms of the fever in eastern Ontario and the United States, might be the cause. But she cautions that more research needs to be done before any conclusions can be drawn. And with ongoing support from the Alberta horse owners, this research will hopefully be carried out during the summer of 2021, in a joint project with UCVM and the Ontario Veterinary College.

Disease notification and timely communication will have a tremendous impact in helping the Canadian horse industry take an active role in monitoring outbreaks, minimizing risks and preventing the spread of infectious disease among our horses. More information can be found on the Canadian Animal Health Surveillance System . You can also sign up for email alerts through the